Flexible Vehicular A Heavy Duty Applications Guide Brick Paving

Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 1 ...... 41 ...... 40 ...... 42 Contents Definitions of Terms of Definitions Referenced Standards Referenced Guide Specification Guide Introduction ...... 30 ...... Subgrade ...... 30 Subbase ...... 31 Base...... 31 ...... Bed Setting Sand ...... 32 Bed Setting Bituminous ...... 33 InstallationPaver ...... 34 Tolerances ...... 37 ...... 38 ...... Considerations In Service Introduction ...... 8 ...... ClassificationSubgrade ...... 8 . . . . . AnalysisTraffic ...... 12 ...... Concepts Design AASHTO .13 ...... 14 ...... Solutions Design AASHTO Concepts Design CALTRANS ...... 16 Bed Systems Setting Bituminous of Design ...... 17 Paving Brick Mortared ...... 17 ...... Detailing ...... 17 ...... ExamplesDesign . . . .21 ...... Introduction...... 22 ...... Subbase MaterialsBase and ...... 22 Base StabilizationSoil and ...... 23 BedsSetting ...... 23 ...... SandJointing ...... 25 ...... PaversBrick ...... 26 ...... MaterialsOther ...... 28 Introduction...... 2 ...... General . .4 ...... Appendix C: Appendix B: References.40 ...... Appendix A: Closing ...... 39 ...... Part III: ConstructionPart ...... 30 Part I: Structural Design and Detailing I: Structural Part ...... 8 II: Materials ...... 22 ...... Part Design Guide for Vehicular Brick Pavements Vehicular Design Guide for . .2 ......

idge and

ark Smallr idge, M idge,

Mark Smallr Mark Steve Jones, Pave Tech, Prior Lake, MN Lake, Prior Tech, Pave Steve Jones, Winston-Salem, NC Winston-Salem, TX Colony, The Associates, Ted Corvey, Pine Hall Brick Company, Brick Hall Pine Corvey, Ted Pittsburgh, PA Pittsburgh, now International Masonry Institute, Masonry International now Brian Trimble, formerly BIA staff, BIA formerly Trimble, Brian

Reston, VA 20191 VA Reston, 11490 Commerce Park Drive Park 11490 Commerce Brick Industry Association Brick Industry Catalog Number: 530 Catalog Published and revised February 2004 February revised and Published assisted in the review of this Guide. this Guide. of review assisted in the the BIA Paving Committee also Committee also BIA Paving the especially helpful. The members of of members The especially helpful. and construction. His assistance was His assistance construction. and experience in segmental paving design paving in segmental experience with considerable expertise and and expertise with considerable Mr. Smallridge is a paving consultant consultant is a paving Smallridge Mr.

content were: content in the development of the the of development in the and a consultant. Instrumental a consultant. and assistance of several members several of assistance Association (BIA) with the Association the staff of the Brick Industry Brick the of staff the This Guide was prepared by by prepared was This Guide Foreword Design Guide for Vehic

Pavement design methods Association recognized Introduction consider two different the need for a rational types of pavement. These The concept of segmental pavements (including clay bricks, approach to provide are “flexible” pavements concrete pavers, stone cobbles, stone and timber sets) is designers with the means and “rigid” pavements. not new. Surviving segmental pavements can be traced of proportioning thickness- Flexible pavements spread back to the Romans and their network of roads, and to es of brick pavements for the surface applied loads to even earlier times. The oldest references to brick surfaced heavy vehicular applica- the underlying layers by streets are believed to date back to Mesopotamian times, tions such as major roads load distribution. The 5,000 years ago. Brick roads and streets provide a stable and streets. The American materials generally require riding surface that is very durable. Brick has been used as Association of State lower strength properties a road paving material in this country since the late 1800’s Highway and with increasing depth, and was used through the early 1900’s when the first Transportation Officials because the stresses reduce national network of roads was constructed. Although the (AASHTO) publication Guide as the load is spread over use of brick as a road surfacing material decreased with for Design of Pavement a wider area. Rigid pave- increasing vehicle speeds, and the improvement of concrete Structures was revised ments spread the surface and asphaltic paving materials and construction methods in 1993 and provided a applied loads by flexure. in the 1930’s and 1940’s, it is still in use today. The nationally accepted method Rigid pavements include a rebirth of central business districts and new festival that could be adapted to portland cement concrete marketplaces demands that street and pedestrian areas consider the flexible brick slab and brick pavers set in be made of materials with a more human scale. The surface. Research on flexi- mortar. A rigid pavement’s appearance, strength, warmth, and flexibility of brick ble pavements had demon- thickness is frequently less meet this challenge. strated the equivalency of than that of an equivalent the brick and sand bed Present day practices enable bricks to be set using three flexible pavement. construction with other basic methods when they are constructed as a pavement pavement materials consid- Prior to the publication surfacing material. These are the sand set, bituminous ered in the AASHTO Design of the first edition of this set and mortar set methods. The former two methods are Guide. Therefore, it was Guide in 1993, the struc- flexible in nature and are covered in this publication. only necessary to develop a tural design of brick pave- They are able to accommodate surface applied loads and suitable layer coefficient ments had generally been environmentally induced stresses without the need for for the brick and sand bed based upon empirical discontinuities such as movement joints. Mortar set brick in order to apply the methods. Their use had surfaces are considered to be rigid, and require regular AASHTO flexible pavement been primarily for pedestri- placement of movement joints. They are covered in other design methodology to the an areas and streets sub- publications, including BIA Technical Notes on Brick brick surfaced pavement. ject to only light traffic. Construction 14 Series. The Brick Industry

2 ular Brick Pavements Flexible Vehicular Brick Paving: Heavy Duty Applications Guide Information in this Guide is able need to include con- ed in this Guide are not based on research and sideration of rigid pave- intended as a replacement development carried out ment where portland to the advice of an experi- around the world. cement concrete was man- enced pavement designer. dated below the brick sur- Although the proposed The previous version of this facing, as this was not cov- pavement sections may be Guide provided instruction ered in the previous ver- appropriate in developing that was very comprehen- sion. In addition to these preliminary sections and sive; however, many users revisions related to the budget costs, it is recom- expressed a need for a sim- AASHTO design method, mended that an engineer plified method of designing this edition also discusses with appropriate pavement flexible brick pavements. an alternative design experience certify the final This version of the Guide method for use in those design. provides such a method states that have adopted based upon specific appli- the Caltrans design method cations and site conditions. or derivations thereof. The design solutions were prepared in accordance This Guide is intended to with the AASHTO method, aid in the proper design, and the input values are specification, and installa- declared in the relevant tion of brick paving sys- sections of this Guide. tems. The designs present- There was also an identifi-

3 Edge Restraint Brick Pavers General Jointing Sand Setting Bed Flexible brick pavements, as defined in this Guide, Wearing consist of sand set or Surface bituminous set brick pavers over layers of conventional pavement materials. The Base flexible brick pavement shown in Figure 1 consists of a compacted subgrade Subbase beneath a subbase layer, base layer, and setting bed Subgrade surfaced with brick pavers and jointing sand. A subbase may not always be necessary between the Figure 1: Flexible Brick Pavement subgrade and the base. An edge restraint is provided adjacent brick pavers around the flexible brick through friction. Interlock pavement as part of the increases over time as the system. Sand set brick joint sand becomes thor- pavers, and to a lesser oughly compacted and extent bituminous set brick debris builds up in the pavers, with sand filled joints. When interlock is joints, develop interlock present, the wearing surface between adjacent pavers, contributes to the strength which distributes the of the system. Specially- applied loads into the shaped pavers provide little underlying layers. This additional contribution to does not occur with mortar vertical interlock. However, set pavers. Mortared brick some bond patterns, such as Displaced Sand Displaced Sand paving is only used over a herringbone, help to concrete slab and is not distribute horizontal loads. covered in this Guide. In areas subjected to heavy No Vertical Interlock Although this pavement vehicular traffic, the brick type has been used success- pavers may be required to Shear fully, the emphasis in this have a minimum thickness Guide is on flexible wearing to achieve sufficient surfaces. Information interlock. on other types of brick pavements can be found in Adequate design and con- Vertical Interlock BIA Technical Notes on Brick struction results in three types of interlock: vertical Construction 14 Series. Figure 2: Vertical Interlock interlock, rotational inter- Interlock is a phenomenon lock, and horizontal inter- that occurs in segmental lock. See Figure 2. If a ver- pavements as a result of tical load were applied to a the interaction of the single brick in a pavement pavers and the jointing without vertical interlock, sand between the pavers. that brick would be forced The tight, sand-filled joints down between adjacent transfer loads between bricks, transmitting concen-

4 Horizontal Displacement Flexible Vehicular Brick Paving: Heavy Duty Applications Guide No Rotational Interlock

Figure 5: Horizontal Load Interlock

trated stresses onto the set- Horizontal interlock is not ting bed. Brick pavers that achieved if horizontal move- Rotational Interlock are compacted into the set- ment is allowed. In vehicu- ting bed and have well con- lar traffic areas, horizontal solidated sand in the joints braking, cornering and Figure 3: Rotational Interlock between them provide shear accelerating forces try to resistance in the wearing move pavers along the road; surface. Thus, the load is this is known as creep. spread over a wide area of Sand filled joints and an setting bed. See Figure 2. interlocking bond pattern Sand set pavers develop transfer these forces within greater vertical interlock a paving area to rigid edg- than bituminous set pavers ing. See Figure 4. Loads as they are vibrated to com- created by turning vehicular pact the sand bed and den- traffic are distributed more sify the joint sand to a evenly in all directions by a higher degree. herringbone pattern than by running bond pattern, If a load is applied asym- which has acceptable hori- metrically to an individual Horizontal zontal interlock in only one Displacement brick, the brick may rotate, direction. See Figure 5. No Horizontal Interlock displacing the setting bed Basket weave patterns may and adjacent bricks. have continuous joints in Rotational interlock holds two directions, resulting in the brick in place while unacceptable horizontal rigid edge restraints prevent interlock. Sand set brick the bricks from moving lat- pavers initially develop erally, thereby eliminating greater horizontal interlock rotation. See Figure 3. Horizontal Interlock than bituminous set brick pavers as the joint sand is better compacted. Figure 4: Horizontal Interlock 5 TABLE 1: Brick Paving System Selection Guide System Advantages Disadvantages Flexible brick paving • Most durable over time • May require a thicker base over flexible base (Fig.6a) • Easy to repair utilities • Permits some water percolation through system • Usually most economical • Allows use of semi-skilled labor

Flexible brick paving over • Good as an overlay to existing pavement • Slightly more expensive semi-rigid base (Fig.6b) • Good over poor soils or small,confined areas • Better aesthetic repairs than asphalt

Flexible paving over • Good as an overlay to existing pavement • Requires good drainage rigid base (Fig.6c) • Good over poor soils or small confined areas • More expensive • Better aesthetic repairs than continuous concrete • Vulnerable to frost heave

Sand setting system • Good load transfer • Susceptible to deficiencies in the bedding sand • Simple and expedient installation • Susceptible to sand loss and creep issues • Pavers easily reused for repairs

Bituminous setting system • Enhanced water resistance • More expensive and slower to install • Good containment of setting bed material • Pavers difficult to salvage during repair work • Less onerous edge restraint requirements • Poor tolerance to paver thickness variations or poor base elevations

Mortared paving over • Matches adjacent walls with mortar joints • Must have a concrete base rigid base (Fig.6d) • Good over poor soils • Most costly of all brick paving • Can be used on steeper grades • Requires maintenance of mortar joints • Requires movement joints

Although a flexible brick to slow traffic in residen- pavement provides a tial neighborhoods. durable surface for light However, segmental pave- or heavy vehicular appli- ments are not recom- cations, the surface of a mended where vehicle segmental pavement may speeds exceed 40 mph (64 not provide a smooth ride kph). at high speeds. Brick roads tend to slow traffic Deciding on the appropri- as subtle variations in the ate brick paving system to surface cause decreasing use is important to ensure ride comfort as speed proper performance. increases. These varia- Since brick can be used in tions help reduce speeds a variety of ways, as in areas where faster shown in Figure 6, Table 1 vehicular traffic may be a is provided to assist in concern. This is one of selecting the most appro- many traffic calming priate system. measures that cities use

6 Figure 6: Brick Paving Systems

Mortarless Brick Paving Mortarless Brick Paving 1 IN. (25MM) Sand Setting Bed 1 IN. (25MM) Sand Setting Bed MIN. 4IN. (100MM) Concrete Base MIN. 4IN. (100MM) Compacted Aggregate Base Flexible Vehicular Brick Paving: Heavy Duty Applications Guide

Compacted Subgrade

Compacted Subgrade Compacted Subbase

Figure 6a: Mortarless Brick Paving Figure 6c: Mortarless Brick Paving Aggregate Base Concrete Base

Mortarless Brick Paving Mortared Brick Paving

Modified Asphalt Adhesive 3/8 IN. to 1/2 IN. (10MM to 13MM) Mortar Setting Bed

3/4 IN. (19MM) Bituminous Setting Bed MIN. 4 IN. (100MM) Concrete Base

Tack Coat

MIN. 4 IN. (100MM) Asphalt Base

Compacted Subgrade Compacted Subbase Compacted Subgrade Compacted Subbase

Figure 6b: Mortarless Brick Paving Figure 6d: Mortared Brick Paving Asphalt Base Concrete Base

7 Part I: Structural Design Introduction Subgrade The AASHTO methodology was described in detail in the first edition of this Guide. Direction was given on deter- Classification mining the amount of traffic that would use the pavement, The subgrade is classified by the existing soil dependent on the many factors identified in the 1993 AASHTO Design Guide. Tables were provided for calculating conditions, the environment and drainage. the estimated traffic in the design lane based upon The more accurate the subgrade classification, axle loads, equivalency factors, structural numbers, growth the better the performance of the pavement. factors and lane distribution factors. The equations used to calculate the required structural number for the pavement, and to proportion the individual pavement layers were set out, along with figures and tables to assess the layer and drainage coefficients necessary to design the pavement. In Soil Conditions addition, nomographs and design examples were provided to The existing soil conditions engineering properties clarify the procedure. for a project should be of the soils over which determined prior to the pavement will be This version of the Guide provides a method based upon commencing the design constructed: specific applications and site conditions rather than the of the pavement sections. • Grain-size distribution: more complex procedure of the first edition. The design A geotechnical engineer sieve analysis test and who specializes in site solutions were prepared in accordance with the AASHTO hydrometer test to deter- methodology, and the input values are declared in the rele- investigation work will mine the percentage of vant sections. Although the proposed pavement sections generally test and classify the individual grain sizes may be appropriate in developing preliminary sections and the soil conditions for in the sample; budget costs, it is recommended that the final design be the project area. Testing • Atterberg Limits: consis- certified by an engineer with pavement design experience. will be carried out at the tency tests to determine project site and samples the moisture content at In addition to these revisions related to the AASHTO design will be recovered for which the sample changes method, this edition also discusses an alternative design additional testing in from a semi-solid state to method for use in those states that have adopted the the laboratory. a plastic state (Plastic Caltrans design method or derivations thereof. Design solu- Limit) and from a plastic tions are not provided using this method, but gravel equiva- The site investigation state to a liquid state lent factors are suggested for use with the Caltrans manual, should include test pits (Liquid Limit); so that it can be adapted to consider brick pavers. and borings along the • Natural moisture content: alignment of the road test to determine the in- Because of the range of climates and the variability of soils, or street, or over the area place moisture content of base and subbase materials, designers must use good engi- of the pavement. Samples the soil; neering judgment in detailing a flexible brick paving should be collected for system. The designer should be acquainted with site condi- the following laboratory • Natural Density: test to tions and use all available resources to create a cost-effec- tests considered essential determine the in-place density of the soil; tive solution. Consult references listed at the end of this to determine the Guide for more information.

8 n and Detailing

• Dry density/optimum out. The values are greatly procedures. One procedure deformation in the materi- moisture content relation- affected by the degree of calculates the estimated al. The R-value is deter- ship (standard or modi- compaction and the mois- thickness of the overlying mined at the moisture con- fied): compaction test to ture content of the speci- pavement layers required to tent and density at which determine the ideal mois- men. The test should be maintain the state of com- the thickness of overlying ture content to achieve conducted on a specimen paction of the material. materials is similar in the Flexible Vehicular Brick Paving: Heavy Duty Applications Guide the specified state of compacted to a density rep- The other procedure esti- two procedures. compaction; resentative of the material mates the thickness of the • Strength tests [California to be used in the pave- overlying pavement layers Bearing Ratio (CBR) or ment, or alternatively at a required to prevent plastic Resistance Value (R- range of densities likely to value)]: mechanical tests be encountered. To repre- to determine the bearing The AASHTO design method uses the resilient modulus (MR) sent the material’s poten- capacity of the soil for as the design input for the subgrade properties. The mean tial moisture condition in use in the design. the pavement, the test value of all test results for each pavement section or soil The CBR test method is set should be conducted on type should be used for design. The test to directly deter- out in ASTM D 1883 Test specimens that have been mine MR is not widely used, so AASHTO has proposed the Method for CBR of soaked after compaction following relationships between the CBR and R-value test Laboratory Compacted Soils for a period of four days. results. These relationships are as follows: (AASHTO T193). It can be conducted on treated and The R-value test method is M (MPa) = 10.3 X CBR (Eq. 1) untreated base, subbase set out in ASTM D 2844 R Where: M is the resilient modulus and subgrade materials. Test Method for Resistance R This test is a comparative R-Value and Expansion and CBR is the California Bearing Ratio measure of the load-bear- Pressure of Compacted Soils ing capacity of a soil. It (AASHTO T190). It can be MR (MPa) = 6.9 + 3.8 X R-value (Eq. 2) measures the load required conducted on treated and The Caltrans design method uses the R-value as the design to drive a standard plunger untreated base, subbase input for the subgrade properties. The lowest R-value a set depth into a sample and subgrade materials, but should be used for design over a section of pavement. of soil at a standard rate of the test can only be under- However, if there are one or two significantly lower R-val- penetration. The CBR taken in the laboratory. ues in a localized section, consideration should be given to value is the ratio of the For base, subbase and non- replacing these areas with better material and using the load measured in the test expansive granular soils, next lowest value. and the load used to the R-value is determined at a density equivalent to achieve the same penetra- This Guide provides design solutions based on five subgrade the density used during tion in a standard sample categories as set out in Table 2. The table provides CBR construction. For cohesive of crushed stone. The test and R-values for each subgrade category, based upon rela- soils and expansive granu- is generally undertaken in tionships to the resilient modulus value M as set out in lar materials, the R-value R the laboratory, but in-place Equations (1) and (2). Soils with a CBR value of less than test involves two separate tests can also be carried 3.0 or R-value of less than 6 require some form of improve-

9 TABLE 2: Subgrade Categories M145, Classification of Soils are classified in seven main and Soil-Aggregate Mixtures groups (and in twelve sub- Subgrade Category CBR Range R-value Range for Highway Construction. groups) based upon their grain-size distribution and Unsuitable < 2.9 < 6 In the USCS, the soils are Atterberg Limits. The two Poor 3.0 - 5.9 6 - 13 classified in twenty-five systems are given in Tables Fair 6.0 - 9.9 14 - 24 groups by two letter desig- 3 and 4, in a manner that Good 10.0 - 14.9 25 - 38 nations dependent on the correlates each group with Excellent > 15.0 >38 soil type and physical prop- the suggested subgrade cat- erties. The first letter rep- egories (U -unsatisfactory, P - poor, F - fair, G - good, TABLE 3: Subgrade Categories from USCS E - excellent). USCS Environmental/Drainage Conditions Designation Wet Average Dry Frost A geotechnical engineer’s report will include a GW E E E E description of the soils GP E E E E encountered at the project GW-GM E E E G site and will set out the GW-GC E E E G test results. In addition, it GP-GM E E E G will generally provide rec- GP-GC E E E G ommendations on the GM E E E P strength properties of the GC` E E E P soils to be used for design GM-GC E E E P and may contain some SW E E E E design options for the SP G E E E pavement section. If a rec- SW-SM G E E F ommended value is given in SW-SC G E E F the report, this should be SP-SM G E E F used to select the subgrade SP-SC F G E F category (see Table 2). If SM G E E U there is no recommended SC F G E P value, but CBR or R-value SC-SM G E E U test results are given, the CL P F G P average of these values CL-ML P F G U should be used for the ML P F G U AASHTO design methodolo- OL U U U U gy. When the design is to CH P P F P be undertaken using the MH P F F U Caltrans adaptation, the OH U U U U minimum R-value should be used for selecting the sub- ment that is beyond the States, but the two most resents the main soil type grade category. If only the scope of this Guide. They common are the Unified (gravel, sand, silt, clay or subgrade’s USCS or AASHTO are considered unsuitable as Soil Classification System organic), and the second classification is known, a subgrade. (USCS), used for general modifies the first letter Table 3 or 4 can be used to engineering purposes, and based upon the grain-size estimate the subgrade cate- Soils or subgrades are typi- the AASHTO System, used distribution for granular gory from the column titled cally classified into differ- for highway engineering soils or the Atterberg “Average”. The remaining ent groups to represent purposes. The USCS is set Limits for cohesive soils. columns are addressed in their engineering proper- out in ASTM D 2487 and Eleven groups have paired the following section. ties. There are several sys- the AASHTO system is set designations. In the tems used in the United out in AASHTO Standard AASHTO system, the soils

10 determined based upon the will consider these factors Environment and Drainage anticipated loss of strength when providing their recom- Environmental conditions and the quality of in the subgrade. In this mendations. If these values subgrade drainage can have a major effect on case, if the project is located are not available, but the in Regions III or VI on USCS or AASHTO designation the support offered by the subgrade. In wet Figure 7, it will be necessary is known, Tables 3 and 4 climates, poorly drained areas, or those that to use the subgrade category should be used to develop experience freezing conditions, the subgrade from the column for Frost the appropriate subgrade support is likely to be reduced during certain Environmental/ Drainage category. Most pavements periods of the pavement’s life. Conversely, in Conditions. If the project should be designed using the arid climates or well-drained areas, it is likely is located in Regions II or subgrade category from the V, and the project site column for Average that a higher degree of subgrade support will drains poorly, it will also be Environmental/Drainage be experienced during part of the pavement’s necessary to use the Frost Conditions. However, if the life. These factors can have a significant Environmental/ Drainage project is located in Regions effect on the performance of the pavement. Conditions column to deter- I, II or III of Figure 7, and mine the subgrade category, the project site drains poorly, Flexible Vehicular Brick Paving: Heavy Duty Applications Guide since, once again, pavement such that the subgrade Saturation of the subgrade, to affect the subgrade, two thickness is a factor. is frequently saturated, it and the materials in the regions where there is a will be necessary to use pavement section, can lead potential effect from frost, The AASHTO design method the subgrade category to premature distress as but only if the pavement is utilizes an effective resilient from the column for Wet this condition reduces the thin, and two regions not modulus that is derived from Environmental/Drainage strength of these materials. susceptible to frost. the seasonal resilient mod- Conditions. If the project Water can enter the pave- Average depths of frost uli. These vary depending is located in Regions IV, ment through the joints penetration are indicated on the moisture conditions V or VI and the project between bricks, through for the eastern and central of the subgrade during each site drains well, such cracks and joints in the states, although frost season. Such an analysis is that the subgrade is bound base materials, or depths can vary locally beyond the scope of this rarely saturated, it may from a high ground water based on many factors. Guide. It is recommended be appropriate to use the col- condition. The amount of Local data should be used that the design be undertak- umn for Dry Environmental/ water penetrating from the in its place if this is avail- en using a subgrade category Drainage Conditions. surface depends on the able for a specific project as described earlier or from regional climate. site. This is particularly the geotechnical report, as Fluctuations in moisture true in the western states, the geotechnical consultants content can also be prob- and no frost depth data is lematic, leading to changes therefore included in Figure in volume and load sup- 7 for this part of the coun- TABLE 4: Subgrade Categories port. Rapid removal of try. If the depth of frost water from the pavement is penetration is greater than from AASHTO therefore an important the pavement thickness AASHTO Environmental/Drainage Conditions design objective, and a determined in this Guide Designation Wet Average Dry Frost positive drainage system based on one of the first A-1-a E E E E should be considered. three columns of Tables 3 A-1-b E E E G Design of such a system is and 4, it will be necessary A-2-4 E E E U beyond the scope of this to revise the pavement con- A-2-5 E E E U Guide. struction. Either non-frost A-2-6 F G E P susceptible material should A-2-7 G E E P Figure 7 presents the six be added to the thickness A-3 G E E F climatic regions experi- of the pavement section so A-4 P G E U enced in the United States. that it is thicker than the A-5 P P F U It depicts two regions of depth of penetration, or a A-6 P F G P hard freezes where spring revised depth should be A-7-5 P P F P thaw conditions are likely A-7-6 P F G P

11 In this Guide, a simplified Traffic Analysis approach is adopted using pavement classes. Nine The traffic analysis for the project should be undertaken before com- pavement classes are iden- mencing design of the pavement sections. A traffic engineer is typi- tified in Table 5, together cally contracted for this work. When undertaking a design it is nec- with a description of their essary to determine the existing (or initial) traffic volume using the anticipated use and an road, and to estimate the future traffic volumes over the analysis indication of the total period. Based upon these data and local experience, it is necessary to number of ESALs and TI for each class. establish the traffic flow in each direction and in the design lane. Most of the damage to a pavement is caused by truck traffic; passen- The life of the pavement ger cars, pick-ups and light two axle trucks generally have a negligi- can be expressed in a num- ble effect. Using local data on the anticipated types of vehicles that ber of ways depending on will use the road, the number of load applications of each axle group local policy. Two terms are can be calculated. Next, all of the repetitions of each axle group are used in the AASHTO Design Guide covering different converted into the equivalent number of repetitions of one axle load long-term strategies. These condition. are the performance period and the analysis period. The performance period is 30” 35” 40” the length of time that a II pavement will remain serv-

40” iceable before it requires 40” 35” rehabilitation such as an III 35” 30” 25” 25” overlay. The analysis peri- I 40” 20” VI 20” 35” 15” od is the amount of time 15” 10” over which the pavement 6” life is to be considered, 3” including any rehabilitation 10” work. For high volume II roads (collectors and above), an analysis period V 6” of at least thirty years is 3” frequently considered. For Region Characteristics I I Wet, no freeze low volume roads (locals II Wet, freeze/thaw cycling III Wet, hard freeze, spring thaw and below) and all other IV Dry, no freeze V Dry, freeze/thaw cycling IV pavements, a twenty-year VI Dry, hard freeze, spring thaw Average depth of annual frost penetration in inches life is generally acceptable. As rehabilitation of flexible brick pavements cannot be achieved by strengthening Figure 7: Climatic Regions in the United States and Average Depth of Annual Frost Penetration measures without lifting the bricks, this Guide con- In the AASHTO design load (ESAL). Tables in the traffic index (TI). This siders the analysis period methodology, the traffic is AASHTO Design Guide pro- varies in accordance with as the design life of the represented as the equiva- vide values for converting Equation 3 below, except pavement. lent number of load appli- different axle loads into that the TI is rounded to cations of an 18-kip axle ESALs. the nearest 0.5: load that represents the mixed traffic using the In the Caltrans method, TI = 9.0 X (ESAL/106)0.119 pavement. This is known this number of ESALs is (Eq. 3) as an equivalent single axle further converted into a

12 TABLE 5: Pavement Class Description and Traffic Pavement Class Description Design ESALs TI PC-1 Through traffic with access to high-density,regional,commercial and office 9,000,000 11.5 Arterial or Major Street developments,or downtown streets. General traffic mix. PC-2 Through traffic with access to low-density,local,commercial and office 3,000,000 10.0 Major Collector development or high density,residential sub-divisions. General traffic mix. PC-3 Through traffic with access to low-density,neighborhood,commercial 1,000,000 9.0 Minor Collector development or low-density,residential sub-divisions. General traffic mix. PC-4 Public Transport Centralized facility for buses to pick up passengers from other modes of 500,000 8.5 Interchange or Bus Parking transport,or for parking of city or school buses. PC-5 Commercial and Limited through traffic with access to commercial premises and multi-family 330,000 8.0 Residential Local and single-family residential roads. Used by private automobiles,service vehicles and heavy delivery trucks.

PC-6 No through traffic with access to multi-family and single-family residential 110,000 7.0 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide Residential Access properties. Used by private automobiles,service vehicles and light delivery trucks,including limited construction traffic. PC-7 Open parking areas for private automobiles at large facilities with access 90,000 7.0 Facility Parking for emergency vehicles and occasional use by service vehicles or heavy delivery trucks. PC-8 Restricted parking and drop-off areas associated with business premises, 30,000 6.0 Business Parking mostly used by private automobiles and occasional light delivery trucks. No construction traffic over finished surface. PC-9 Predominantly pedestrian traffic,but with access for occasional heavy 10,000 5.0 Commercial Plaza maintenance and emergency vehicles. No construction traffic over finished surface.

The reliability of the Non-highway pavements are AASHTO Design designed pavement section also considered to have a is an important feature in reliability of 75 percent. Concepts the AASHTO design process. This means that 85 percent The reliability of the pave- or 75 percent of the pave- The AASHTO Design Guide is based upon ment is the probability that ments for each respective empirical test results from full-scale road tests it will perform satisfactorily use would achieve or exceed conducted in the 1960’s. As a result of the over its design life for the the design life. measured behavior of the test sections, the traffic and environmental researchers developed a performance equation conditions experienced. The The AASHTO design method uses a subjective measure of upon which design of new pavement sections reliability level adopted in this Guide is taken as an 85 the loss of serviceability and can be achieved. The equation relates the percent likelihood that the failure of the pavement. It design life, in terms of 18 kip ESALs, to a pavement will reach its was developed as an inter- number of different input parameters. These design life (analysis period) pretation of the quality of include the reliability of the pavement, the for pavements with high the ride experienced by the acceptable level of loss in serviceability, the traffic volumes (collectors average road user. A scale from 0 to 5 represents the variability of the traffic predictions and per- and above); and a 75 per- cent likelihood that the quality of the ride and is formance, the structural number and the aver- pavement will reach its known as the Present age subgrade resilient modulus. intended design life for Serviceability Index (PSI). pavements with low traffic A PSI of 0 represents an volumes (locals and below). impassable road while a PSI

13 of 5 represents a perfect road. The change between the ini- tial and final (terminal) PSI, known as the Serviceability AASHTO Design Loss, used in this Guide is taken as 1.7 for high traffic vol- umes and 2.2 for low traffic volumes. This is based upon an Solutions initial value of 4.2 and terminal values of 2.5 and 2.0 respectively. This compares favorably with those used for Tables 8 through 11 of this Guide have been typical flexible pavements. An exception is in pedestrian prepared to provide design solutions to each areas where the potential for trip hazards is an important pavement class and subgrade category. The consideration. Therefore, a serviceability loss of 1.7 is rec- wearing surface is always a 2-5/8 in. (67 mm) ommended in these locations. Other AASHTO reliability paver on a 1 in. (25 mm) setting bed. The parameters are presented in Table 6. bituminous setting bed is usually specified at The variability of the traffic prediction and pavement per- 3/4 in. in thickness, and an adjustment to the formance is taken as 0.35. This is comparable with the fig- developed thicknesses is required as discussed ures used for flexible pavements using asphaltic concrete as in the bituminous setting bed section. The a surface course. base is as indicated in the tables. The structural number is the only parameter directly related Similarly, Table 9 provides to the pavement section. It is derived from the layer coef- Table 8 presents the thick- the required thickness of ficient of each layer, the thickness of each layer, and the ness of graded aggregate graded aggregate subbase drainage coefficient for each layer. This Guide is produced subbase course required for when a cement treated under the assumption that adequate drainage will be pro- each application. The base is used under the bed- vided to the pavement materials such that the latter coeffi- resultant pavement section ding sand. Note that in cient can be taken as 1.0. Typical layer coefficients are will be comprised of 2-5/8 this case the thickness of presented in Table 7, with the default values used in subse- in. (67 mm) thick flexible cement treated base is quent design tables in this Guide. brick surface on 1 in. (25 increased from 4 in. to 6 mm) of bedding sand, over in. (100 to 150 mm) for The values presented in Table 7 can be used to adjust the 4 in. (100 mm) of crushed, traffic levels over 2,000,000 layer thicknesses derived from the design tables. The ratio graded aggregate base on ESALs. Table 10 can be of the layer coefficients can be used to determine the top of the thickness of used when an asphalt equivalent thickness of an alternative material. For exam- graded aggregate subbase treated base is provided. ple, to include a 6-in. (150 mm) thick lime stabilized sub- determined from the table. base it is possible to reduce the aggregate base by Note that the thickness of Table 11 provides typical 0.11/0.14 times the 6-in. (150 mm) thickness, i.e. by 4.5 crushed, graded aggregate portland cement concrete in. (114 mm). Similarly, to replace 8.5 in. (216 mm) of base is increased from 4 in. slab thicknesses, with a graded crushed aggregate (CBR 100) with graded aggregate to 6 in. (100 to 150 mm) 4 in. (100 mm) aggregate (CBR 60) multiply 8.5 by 0.14/0.12, i.e. replace with 10 in. for traffic levels over subbase below and a wear- (254 mm) of graded aggregate. However, it is recommended 500,000 ESALs. An ing surface of flexible brick that the top of the aggregate base directly under the paver unbound base course is not paving. This table is for setting bed always be constructed with graded, crushed considered appropriate for guidance if the bricks are material that is 4 in. (100 mm) thick when the ESALs are traffic levels above to be used over such a below 500,000 or 6 in. (150 mm) thick when the ESALs 2,000,000 ESALs. substrate. Little structural are at 500,000 and above respectively. benefit is provided by the TABLE 6: AASHTO Reliability Parameters bricks in this pavement Pavement Class Reliability Serviceability Loss section, and care needs to PC-1 0.85 1.7 be exercised in ensuring PC-2 0.8 1.7 that detailing allows for PC-3 0.85 1.7 thermal and moisture PC-4 0.75 1.7 induced movement in the PC-5 0.85 2.2 concrete, and for egress of PC-6 0.75 2.2 moisture penetrating the PC-7 0.75 2.2 brick surface. PC-8 0.75 2.2 PC-9 0.75 1.7 14 TABLE 7: Layer Coefficients Pavement Layer Pavement Material or Property Layer Coefficient Pavers on sand setting bed (increases with traffic volume) 0.31 to 0.40 Pavers on bituminous setting bed (increases with traffic volume) 0.30 to 0.37 Cement-treated base 7 day compressive strength 800 psi 0.22 7 day compressive strength 650 psi 0.20 (default) 7 day compressive strength 500 psi 0.17 Asphalt-treated base Marshall stability 1,800 lbs 0.32 Marshall stability 1200 lbs 0.26 (default) Marshall stability 750 lbs 0.20 Aggregate base graded crushed aggregate (CBR 100) 0.14 (default) graded aggregate (CBR 60) 0.12 Subbase graded aggregate (CBR 30) 0.11 cement-stabilized subgrade (250 psi) 0.13 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide lime-stabilized subgrade (150 psi) 0.11 TABLE 8: Graded Aggregate Subbase Thickness Under 4 in. Graded, Crushed Aggregate Base Subgrade Category Pavement Class ESALs TI Poor Fair Good Excellent PC-1 Arterial or Major Street 9,000,000 11.5 N.A. N.A. N.A. N.A. PC-2 Major Collector 3,000,000 10.0 N.A. N.A. N.A. N.A. PC-3 Minor Collector 1,000,000 9.0 15.0* 7.0* 4.0* 0.0* PC-4 Public Transport Interchange or Bus Parking 500,000 8.5 9.5* 4.0* 4.0* 0.0* PC-5 Commercial or Residential Local 330,000 8.0 10.5 4.5 4.0 0.0 PC-6 Residential Access 110,000 7.0 5.5 4.0 0.0 0.0 PC-7 Facility Parking 90,000 7.0 4.5 0.0 0.0 0.0 PC-8 Business Parking 30,000 6.0 4.0 0.0 0.0 0.0 PC-9 Commercial Plaza 10,000 5.0 4.0 0.0 0.0 0.0 * with 6 in.graded,crushed aggregate base

TABLE 9: Graded Aggregate Subbase Thickness Under 4 in. Cement-Treated Base Subgrade Category Pavement Class ESALs TI Poor Fair Good Excellent PC-1 Arterial or Major Street 9,000,000 11.5 24.5* 15.0* 9.0* 6.0* PC-2 Major Collector 3,000,000 10.0 18.0* 9.0* 6.0* 6.0* PC-3 Minor Collector 1,000,000 9.0 15.0 7.5 4.0 4.0 PC-4 Public Transport Interchange or Bus Parking 500,000 8.5 10.0 4.0 0.0 0.0 PC-5 Commercial or Residential Local 330,000 8.0 8.5 4.0 0.0 0.0 PC-6 Residential Access 110,000 7.0 4.0 0.0 0.0 0.0 PC-7 Facility Parking 90,000 7.0 4.0 0.0 0.0 0.0 PC-8 Business Parking 30,000 6.0 4.0 0.0 0.0 0.0 PC-9 Commercial Plaza 10,000 5.0 4.0 0.0 0.0 0.0 * with 6 in.cement treated base 15 TABLE 10: Graded Aggregate Subbase Thickness Under 3 in. Asphalt-Treated Base Subgrade Category Pavement Class ESALs TI Poor Fair Good Excellent PC-1 Arterial or Major Street 9,000,000 11.5 26.0* 16.5* 10.0* 6.0* PC-2 Major Collector 3,000,000 10.0 19.0* 10.5* 6.0* 6.0* PC-3 Minor Collector 1,000,000 9.0 15.5 7.5 4.0 4.0 PC-4 Public Transport Interchange or Bus Parking 500,000 8.5 10.0 4.0 0.0 0.0 PC-5 Commercial or Residential Local 330,000 8.0 8.5 4.0 0.0 0.0 PC-6 Residential Access 110,000 7.0 4.0 0.0 0.0 0.0 PC-7 Facility Parking 90,000 7.0 4.0 0.0 0.0 0.0 PC-8 Business Parking 30,000 6.0 4.0 0.0 0.0 0.0 PC-9 Commercial Plaza 10,000 5.0 4.0 0.0 0.0 0.0 * with 4 in.(150mml) asphalt treated base

TABLE 11: Concrete Slab Thickness with 4 in. Aggregate Subbase Subgrade Category Pavement Class ESALs TI Poor Fair Good Excellent PC-1 Arterial or Major Street 9,000,000 11.5 10.5 10.0 9.5 9.5 PC-2 Major Collector 3,000,000 10.0 9.0 8.5 8.0 7.5 PC-3 Minor Collector 1,000,000 9.0 7.0 6.5 6.0 5.5 PC-4 Public Transport Interchange or Bus Parking 500,000 8.5 6.0 5.5 4.0 4.0 PC-5 Commercial or Residential Local 330,000 8.0 5.5 5.0 4.0 4.0 PC-6 Residential Access 110,000 7.0 5.5 4.0 4.0 4.0 PC-7 Facility Parking 90,000 7.0 4.0 4.0 4.0 4.0 PC-8 Business Parking 30,000 6.0 4.0 4.0 4.0 4.0 PC-9 Commercial Plaza 10,000 5.0 4.0 4.0 4.0 4.0

The Caltrans design The design of the pavement CALTRANS Design method considers the vari- section is based upon a ous pavement materials in relationship between the R- Concepts terms of a gravel factor Value (R), and the Traffic The Caltrans design method is also based (Gf). Tables are included Index (TI) to develop the upon a wide range of information including: in the Caltrans design Gravel Equivalent (GE) for theory, test track studies, experimental manual setting out the the pavement. The rela- pavement sections, observations of pavement gravel factors for various tionship is represented by materials dependent on the Equation 4: performance, and research on materials. materials properties and Pavements are generally designed for a twenty the TI. The gravel factor is GE (mm) = 0.975 X (TI) X year life, but it is accepted that asphalt a representation of the rel- (100-R) (Eq. 4) concrete surfaced pavements will require ative ability of the materi- als to resist the effects of The procedure is carried out maintenance at ten to fifteen years if they from the top of the pave- are to achieve this life. This is generally a traffic loading, when com- pared to an equivalent ment to the bottom. surface material issue, and this Guide assumes thickness of gravel. Treated base layers general- that the brick pavers will provide a twenty ly have an R-value greater year life. that 100 and so the equa- tion is typically applied to

16 the highest layer in the pavement section with an Design of Bituminous Setting R-value less than 100. The thickness of the overlying Bed Systems layers is determined. The Bituminous setting bed systems as shown in Figure 6b can be used in process is then used for the underlying layer, and so on most of the same applications as sand setting bed systems. Higher speed down to the subgrade. The applications are less desirable as the interlock between pavers is reduced. thickness of each layer is Although it has reduced structural benefits, the system can provide better calculated by dividing the moisture protection to the underlying layers. In addition, the bonding GE by the appropriate Gf. action of the system enables the use of pavers with a lower standard of The thickness of each layer dimensional tolerances where wider joints would lead to reduced “lock-up” is generally rounded to the 1 next 0.05 ft (15 mm) incre- in a sand set system. Joint widths of up to /4 inch (6 mm) can be toler- ment. ated, especially in low traffic applications. As there is no vibration used to compact the pavers, chipping is less of a problem, particularly with To allow for deviations from

pavers that do not have chamfers or lugs. This system may also have Flexible Vehicular Brick Paving: Heavy Duty Applications Guide the specified thickness as a advantages where edge restraints are less reliable, or where movement may result of construction pro- cedures the Caltrans be encountered. This typically occurs where pavers are placed against method uses a safety factor steel rails for light rail applications. procedure. This involves adding 0.2 ft (60 mm) to The bituminous setting bed asphalt treated base layer, the GE of the asphalt con- system can be used as an or 1-1/2 in. (38 mm) to the Detailing crete surface material and alternative to a sand set- thickness of the graded, subtracting 0.2 ft (60 mm) ting bed system. The 1 in. crushed aggregate base. No Surface from the GE of the subbase, (25 mm) thick sand setting revision is necessary for Profile or if no subbase is used, bed is replaced by a 3/4 in. the portland cement con- Satisfactory slopes for flexi- from the thickness of the (19 mm) thick asphalt crete sub-slab option. ble paving must be provid- base. The thickness of the coated sand mixture that is ed to avoid ponding water. brick pavers cannot be “bonded” to the underlying A minimum slope of 2 per- changed, and so this prac- pavement layer using a Mortared cent, (1/4 in. per foot or 1 tice needs to be undertak- tack coat. The brick pavers mm per 50 mm), is sug- en between the base and are bonded onto this layer Brick gested for all exterior brick the subbase, if used. with a rubberized asphalt paving. Crowns on roads adhesive. The joints are Paving usually provide adequate Design solutions using the filled with stabilized sand, The structural design of slope. A maximum slope of Caltrans procedure are not but no vibration is used. mortared brick paving fol- 10 percent is recommended presented in this Guide, Consequently, “lock-up” is lows the design of rigid for flexible brick streets however, a Gf of 2.0 is pro- not as well established and pavements. The brick and roads, since larger posed for the brick paver the load spreading is pavers and the mortar set- slopes will cause washout and sand setting bed, and reduced. The base thick- ting bed are not taken into of the jointing sand and 1.8 is proposed for the nesses presented in this account in the thickness braking vehicles will brick pavers on a bitumi- Guide can be used for this design. The design of increase the creep of the nous setting bed, based system; however, the thick- mortared brick paving is pavement. Surface grades upon the above noted typi- ness of the underlying lay- not the aim of this Guide. of up to 15 percent, or cal relationship with equiv- ers needs to be increased. Refer to the AASHTO even 20 percent, can be alency to asphalt concrete. This can be achieved by Design Guide or BIA used on pavement areas This value can be used adding an additional 1 in. Technical Notes 14 Series. subject to slow moving when the Caltrans manual (25 mm) to the thickness traffic or pedestrians. is appropriate for the of the cement treated base design, rather than the However, joint sand stabi- layer, 3/4 in. (19 mm) to lization, as well as a high AASHTO methodology. the thickness of the

17 level of installation quality, portland cement concrete of the setting bed into subjected to heavy vehicu- is desirable to reduce creep slab or a cement or asphalt sub-surface drains. A lar traffic. This is required that occurs. treated base. Weep holes drainage layer of open for sand setting beds and placed vertically through graded aggregate may also recommended for bitumi- Drainage the portland cement con- be used, but requires prop- nous setting beds. The Drainage is one of the most crete slab may be neces- er planning, designing and pattern can be oriented at important design require- sary depending on the specifications. Design and 45 degrees or 90 degrees to ments, since improper environmental conditions. detailing of such systems the direction of traffic. It drainage may cause failure Drainage is less of a con- are not included in this is not necessary to turn of the pavement, erosion of cern with bituminous set- Guide, and the reader is the pattern at corners and the base or subbase, possi- ting beds as some water directed to the references bends, as the horizontal ble deterioration of the will percolate through for several manuals on interlock is good in all pavers, or slippery pave- them. It may be necessary this subject. directions. ments. Drainage needs to to provide a sub-surface Many of the pavements laid be considered at three lev- drainage system. Sub-sur- Bond Patterns in the 19th and 20th els in the pavement. These face drainage weeps should Many different bond pat- Century were laid in run- are at the surface, to the be provided at low points terns exist, providing dif- ning bond, either directly setting materials and to and at the edge restraints ferent aesthetic effects, a across the streets, or occa- the pavement structure and to drain water to the pave- few of which are shown in sionally at up to 45 subgrade. Surface drainage ment edge or storm drains. Figure 8. Herringbone pro- degrees across them. is undertaken in accor- A perforated pipe wrapped vides the best resistance to Running bond patterns dance with standard design with an appropriate geot- the horizontal forces from have continuous joints in concepts for pavement extile material may be accelerating, braking and one direction. They do not areas. The pavement sur- used. The geotextile is turning of wheels, and necessary to keep small transfer loads well along face should be finished 1/8 should be used in areas particles from washing out the continuous joints, and to 1/4 in. (3 to 6 mm) above drainage gratings to allow for potential second- ary compaction of the set- ting bed under trafficking. Surface profiles are covered in the previous paragraph. The bond pattern may affect the flow rate of water over the surface of Running Bond the paving, as water tends Basketweave to flow along the joint lines. Surface runoff will increase with time as the joints become filled with debris, however, some water will penetrate the brick surface layer.

Water that penetrates the wearing surface should be drained away from the set- ting bed and base when the underlying layers are not free-draining. This is par- Herringbone Stack Bond ticularly the case when the setting bed is placed over a Figure 8: Bond Patterns 18 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 19 in. (3 mm) high 8 / 1 against the concrete so concrete the against is accommoda- that there settle- secondary tion for bed setting the of ment is also It traffic. under cut the keep to advisable the brick against pieces of as as large divider edge pieces with no possible, a than a quarter of less par- are Thin slivers paver. dam- to ticularly vulnerable positions. at these age can be gained benefit Some a header, incorporating by course string or sailor, concrete the to adjacent edge. Traffic buttons are fre- are buttons Traffic mark- as lane used quently roads and in streets ings is clearance snow where Traffic Buttons, and Reflectors Paint Markings required, by a single saw- a single by required, a care- by or line, cut joint series of fully introduced to joints sawcut staggered continuity. maintain frequently also are Inlays brick of a panel where used as is incorporated pavers Such feature. an entrance surround- usually are inlays or dividers, concrete ed by concrete cement portland detailing When pavement. is impor- an inlay it such the of sides that the tant so that vertical are dividers can be generated interlock the and bricks the between brick pavers The concrete. approxi- be finished should mately In many pavement areas, pavement In many laid are brick pavers the elements concrete between pavement the that divide are These sections. into 16 in. (200 typically 8 to per- The 400 mm) wide. to that ception is frequently oppor- the this will provide pat- the change tunity to or that by tern orientation fixed such incorporating it will be possible features the of creep prevent to In actuality, brick pavers. a discontinu- it introduces that pavement the ity into within a weakness creates Placement area. traffic the open- small cut pieces, of ing of the joints, and set- often pavers the of tlement locations. at these occurs dividers concrete Therefore recommended. not are pattern ori- in the Changes by can be formed entation or a header incorporating if a bricks of course sailor is type feature band compaction of the brick the of compaction All edge begins. pavement be placed should restraints the at least of a depth to bed. setting the of bottom required are restraints Edge bitu- set and both sand for methods, setting minous former the although con- robust more requires is important It struction. the of face inside that the so is vertical restraint edge can be laid pavers that the a it without against will that joint tapered integrity. the reduce Concrete and Dividers Inlays in. (2 mm) 16 / 1 lowable in stan- lowable

Edge Restraints neces- are restraints Edge of perimeter the sary along prevent to pavement the the of movement lateral set- the of loss and pavers edge bed. The ting to be able should restraints loads anticipated resist with minimal movement in interlock. maintain to order can be restraints Edge the laying before placed those bed, and setting concrete incorporating before be cured should coincide with the building with the coincide or other pits, tree grids, designs Other features. in her- created been have bands or bond ringbone color different using out a setting When pavers. dimen- fixed pattern using or different sion modules to it is important colors, individ- that the remember exact not are ual bricks pattern a modular In sizes. a consistent under or over sizing of the of sizing or over under al bricks, toler- manufacturing dard a to will soon lead ances, sev- of or overrun shortfall in a grid mod- inches eral only be This should ule. the cutting by overcome the fit, as spacing to bricks joints with wider pavers structural can affect the pavement. the of integrity col- different mixing When in a pattern pavers of ors to it is necessary area, of an understanding have different for potential the desired sizes so that the is achieved. appearance

pavers in modules that in modules pavers installed using the brick the using installed other facilities have been have facilities other Some pedestrian plazas and pedestrian Some wheel turning. wheel is any likelihood of in-place of likelihood is any with such patterns if there patterns with such care needs to be exercised to needs care other bond patterns. Great patterns. bond other bond pattern more than pattern more bond and misalignment of the of misalignment and irregularities of the pavers the of irregularities bond patterns tend to show to tend patterns bond Basketweave and stack and Basketweave affect installation quality. affect installation lar module, which may lar module, bone bond using an irregu- using bond bone not align with a herring- not rule, although joints will joints although rule, not have to follow this follow to have not bond and stack bond do bond stack and bond Herringbone bond, running bond, Herringbone ment of the pattern. the of ment width) for proper align- proper width) for is 2:1 or 3:1 (length: bonding ratio of the paver the of ratio bonding flexible pavement the pavement flexible weave patterns laid in a patterns weave directions. For most basket most For directions. joints in two perpendicular in two joints patterns include continuous include patterns these arrangements, the arrangements, these Spanish bond. In all of Spanish bond. these patterns, such as such patterns, these applies to derivations of derivations applies to pedestrian areas. This also areas. pedestrian bond, can be used in can be used bond, as basketweave and stack and as basketweave Other bond patterns, such patterns, bond Other of the continuous joints. pendicular to the direction the to pendicular the traffic should run per- should traffic the traffic volume paved areas paved volume traffic roads and streets. For low For streets. and roads mended for high volume high for mended bond pattern is not recom- pattern is not bond minimize creep. Running creep. minimize between pavers in order to in order pavers between They require smaller joints smaller require They necessary with their use. with their necessary so careful consideration is consideration so careful not an issue. These buttons fic markings is not a legis- large horizontal pressure and reflectors are generally lated requirement, inlaying into the brick paver layer, secured on the pavement contrasting colored pavers possibly causing paver surface with an epoxy adhe- can provide the most movement that may result sive. Setting onto individ- durable option. in chipping and spalling of ual brick pavers can be the pavers, and in extreme detrimental to the pave- Movement conditions heaving of the ment. The impact from surface. It is therefore nec- vehicle tires can loosen and Joints essary to continue expan- even dislodge the bricks. It Pavement materials expand sion joints through the is recommended that alter- and contract as a result of brick and setting bed layer native means of lane mark- temperature and moisture by incorporating edge ings are adopted for brick changes. Flexible pave- restraints on either side of pavers, or that larger, low- ment materials, such as the joint. This should be profile buttons are used aggregate, asphalt concrete applied to both sand set that fix to more than one and cement treated base and bituminous set pavers. paver. One effective solu- materials, distribute this tion has been to inlay con- movement over the entire Portland cement concrete crete pavers that have a pavement areas such that slabs are also provided with specialized top surface fin- localized strains are very contraction joints to control ish. As concrete pavers are small. As a result the cracking during curing. typically 3-1/8 (80 mm) pavers are unaffected by Movement at these loca- thick, they protrude above the underlying movement. tions is less than at expan- the pavement surface suffi- Brick pavers behave simi- sion joints, and it is not ciently to create tire feed- larly, with any movement normally necessary to back to indicate their pres- taken up in the joints reflect the joints into the ence. between pavers without surfacing if the underlying putting stress on the brick contraction joints are at There are several different or edging. Expansion less than 10 ft (3 m) cen- types of traffic marking joints are therefore not ters. In order to distribute methods for the pavement typically required in such the movement over a wider surface. These include flexible brick pavements. area it is beneficial to cover adhesive strips, paints, and However, when a portland the control joints with a thermo-plastics. When in cement concrete slab, used strip of geotextiles under service, the individual brick under the flexible brick the sand bedding course. pavers continue to move paving wearing surface, This is not done under bitu- independently of each other expands and contracts, the minous setting materials. to a slight degree. As such, movement is concentrated the joints open and close a at the joints between the small amount when a wheel slabs. This movement will passes over them. This be reflected into the over- movement is often suffi- lying pavers, which can be cient to cause cracking of detrimental to the pave- the adhesive strip and ther- ment. When the concrete mo-plastic markings. contracts, it causes the Although thinner paint overlying joints to open. markings frequently have a This results in a loss of shorter service life on other interlock, settling of the pavement materials, they pavers and a loss of integri- may be more cost effective ty. When the concrete on brick paved surfaces. expands it causes the joints Where the visibility of traf- to close. This can impose

20 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 21 4 / in. 3 8 in. / 5 in. 2 8 / 1 / 5 in. 8 / 7 in. asphaltic setting bed. in. asphaltic setting 4 / Consider bituminous set bricks on a set bricks bituminous Consider 3 Boston MA Boston Clayey sand with an average CBR value CBR value with an average sand Clayey A downtown thoroughfare where traffic traffic where thoroughfare A downtown ESALs 6 in. The total pavement thickness would be 18- would thickness pavement total in. The 8 / 3 in. bituminous setting bed, add 1 in. to the 6 in. of the 1 in. to add bed, setting in. bituminous 4 / Add 6 in. aggregate subbase owing to frost penetration. frost to subbase owing in. aggregate 6 Add increase would strength of loss the (With poor subgrade, 6 in. of than adding 1 in., rather by thickness concrete subbase) aggregate brick pavers on 1 in. sand setting bed, laid on 6 in. 650 setting in. sand on 1 brick pavers consider To subbase. aggregate 9 in. graded psi CTB over 3 penetration frost exceed to aggregate 4 in. to in. Add to conditions poor subgrade (Considering depth. additional support requires of loss accommodate 9) Table 15.5 in from be 2- would thickness pavement 11, the Table From Example 2 Example Location: Project type: Project will life design the over traffic that the indicate studies be 8x10 The total pavement thickness would be 16- would thickness pavement total The brick pavers on 1 in. sand setting bed, laid on 9- setting on 1 in. sand brick pavers Soil conditions: 11. of options: Pavement strength compressive (7-day base course treated cement cement a portland subbase and 800 psi) on an aggregate subbase. slab on an aggregate concrete II (wet in Region is located project 7, the Figure From 22 in. is around depth Frost cycling). with freeze/thaw PC-1 (Arterial or Class is Pavement 5, the Table From 9,000,000 of expectations traffic with Street), Major 20 years. over ESALs for good are soil conditions 3, the 2 and Tables From conditions. frost poor for and conditions average CTB is 0.22 the for coefficient layer 7, the Table From 2- will be thickness pavement 9, the Table From CTB. To consider 800 psi CTB, multiply 7 in. by 0.2/0.22 7 in. by 800 psi CTB, multiply consider To CTB. = 6- 4 in. graded slabs over concrete cement portland thickness in pavement No increase subbase. aggregate a use to is required in. 8 / 5 in. 8 / 5 in. of graded aggre- graded in. of 2 / in. (67 mm) brick 1 8 / 5 in. (Considering the subgrade subgrade the in. (Considering 8 / 1 in. brick pavers on 1 in. sand set- on 1 in. sand in. brick pavers 8 Consider 2-Consider / 5 Phoenix, AZ Phoenix, Low plasticity clay CL plasticity clay Low A residential sub-division local collector sub-division local A residential

in. graded aggregate subbase. The total pavement total The subbase. aggregate in. graded

2

/ 1

ignored owing to the clay subgrade) the to owing ignored the full depth of graded aggregate subbase, but is subbase, aggregate graded of full depth the (Considering the subgrade similarly drained would save save would similarly drained subgrade the (Considering

From Table 10, the pavement thickness would be 2- would thickness pavement 10, the Table From gate subbase, and so is ignored for the clay subgrade) the for so is ignored and gate subbase, 4- ting bed, laid on 4 in. graded crushed aggregate base over aggregate crushed bed, laid on 4 in. graded ting thickness will be 2- thickness From Table 8 and the design requirements, the pavement the requirements, design the 8 and Table From conditions and good for dry conditions. for good and conditions From Table 3 the soil conditions are fair for average average for fair are soil conditions 3 the Table From ESALs over 20 years. 20 over ESALs Residential Local) with traffic expectations of 330,000 of expectations Local) with traffic Residential From Table 5 the Pavement Class is PC-5 (Commercial and Class is PC-5 (Commercial Pavement 5 the Table From depth is insignificant. depth freeze/thaw cycling). Local data indicates that frost Local data indicates cycling). freeze/thaw From Figure 7 the project is located in Region V (dry with in Region is located project 7 the Figure From an asphalt treated base on aggregate subbase. base on aggregate an asphalt treated aggregate base course on aggregate subbase and subbase and on aggregate course base aggregate pavers on a 1 in. (25 mm) sand setting bed, with an setting on a 1 in. (25 mm) sand pavers Soil conditions: heavy delivery trucks. delivery heavy Project type: Project and vehicles service automobiles, private by Used street. options: Pavement

Project Location: Project Example 1 Example The total pavement thickness would be 10- would thickness pavement total The asphalt treated base over 4 in. graded aggregate subbase. aggregate 4 in. graded base over asphalt treated brick pavers on 1 in. sand setting bed, laid on 3 in. setting on 1 in. sand brick pavers similarly drained would only save only save would similarly drained thickness would be 12- would thickness Design Examples Design Part II: Materials

Aggregates aggregates may not be suf- ficient to achieve interlock Introduction The National Stone within the aggregate layer Association has provided The performance of any pavement is only as and will not transfer loads gradation limits for base good as the base, subbase and soil on which properly. Open graded (gap and subbase aggregate it is laid. Quality materials for every layer in graded) aggregates can be materials, see Table 12. used to promote water the pavement system are vitally important to This table is similar to drainage in areas subjected good performance. Materials should conform requirements found in to frost heave to minimize to state or local department of transportation ASTM D 2940 Specification damage. Geotextiles may (DOT) specifications, ASTM standards, or other for Graded Aggregate be needed to prevent intru- Material for Bases or applicable industry standards. Project specifi- sion of smaller material Subbases for Highways or cations typically require submission of into the open graded aggre- Airports. qualifying tests set by the standards. gates. Crushed, quarry processed asphalt-treated aggregates; aggregate is preferred Asphalt Bases Base and or concrete and asphalt because of its ease of con- New or existing asphalt bases. Subbases are usually struction. The maximum bases can be used for flexi- Subbase composed of aggregate size of aggregate to be ble brick pavements. materials. Aggregate base used in construction may Specification of asphalt Materials and subbase materials, depend on the size of the concrete should follow project and the size of industry standards or local Some pavement systems including cement- and lime- equipment being used. DOT requirements. The contain only a base, while stabilized materials, are Proper gradation of materi- adequacy of existing others contain a base and a commonly specified in local als is required to achieve asphalt and the materials subbase. See Figure 1 for state and municipal stan- adequate compaction. beneath should be verified. location of layers. The dards for highway construc- Layers consisting of single- quality or type of base and tion. All materials should size aggregate will not con- subbase materials is usually conform to state or local Concrete Bases solidate during compaction dictated by the design DOT specifications. New and existing concrete and should not be used. requirements. The design Materials conforming to bases can be used for flexi- ASTM or other industry tables are based on various For flexible brick pave- ble brick pavements. New standards can be used as CBR values for the aggre- ments subjected to pedes- concrete slabs should be alternates. The choice and gate layers, and compres- trian and light vehicular specified, with reinforce- quality of base and subbase sive strength or Marshall traffic, aggregate graded to ment as needed, and con- materials influences the structed according to stability for the cement and “3/4 minus”, similar to the performance of the pave- asphalt treated layers. gradations in Table 12, is industry practice. Concrete ment. Typically, each layer usually sufficient as a base bases should be properly Base materials may consist material can resist progres- material because it is easy cured before installing the of unbound granular mate- sively higher stresses from to work with and is readily flexible brick paving. High rials, such as crushed aggre- the subgrade upward to the available. Smaller graded early strength cement may gate; cement-treated or wearing course. aggregates or rounded be used to reduce the time

22 before the wearing surface TABLE 12: Gradation for Base and Subbase is placed. Existing concrete slabs should be checked for (National Stone Association) appropriate strength and Grading Requirements for Dense Graded Material repaired or reinforced as Sieve Size Design Rangea Job Mix Tolerances necessary. A geotextile can Percent Passing,by Weight Percent Passing by Weight be used where there is a Bases Sub-bases Bases Subbases possibility of loss of sand 2 in.(50 mm) 100 100 -2 - 3 through cracks or holes in the existing slab. The ade- 1-1/2 (37.5) 95 to 100 90 to 100 ± 5 ± 5 quacy of the materials beneath the existing con- 3/4 in (19 mm) 70 to 89 — ± 8 — crete slab should be veri- fied. 3/8 in. (10 mm) 50 to 70 — ± 8 — Soil and Base No.4 (4.75) 35 to 55 30 to 60 ± 8 ± 1- Stabilization No.30 (600 µm) 12 to 25 — ± 5 — Flexible Vehicular Brick Paving: Heavy Duty Applications Guide No.200 (75 µm) 0 to 8b 0 to 12b ±3 ±5 Subgrade soils or granular material unsuitable for use a Job mix formula should be selected with due regard to availability of materials in the area of the project. Job mix tolerances alone may be treated to pro- may permit acceptance of test results outside the design range. duce a stronger layer. The b Determine by wet sieving. Where climatic conditions (temperature and availability of free moisture) indicate that in order to subgrade soil may be stabi- prevent damage by frost action a lower percentage passing the No.200 sieve than permitted above,appropriate lower percent- lized by adding portland ages shall be specified. cement or lime, depending on the quality of the soil. occurring, washed silica sand charge of ball bearings, on a Subbase and base materials Setting with no silt content should bottle roller for six hours. may be improved by adding be used. The gradation for The sand particles wear or portland cement, lime, Beds the silica sand in channel- break down in the process, asphalt or pozzolanic materi- ized traffic should be as generating finer particles. als. Modifying unsuitable Sand Setting shown in Table 14 and no The increase in fine particles materials is considered when Bed more than 0.3% passing the passing the No. 50, No.100 economically feasible or 75 µm (No. 200) sieve. and No. 200 sieve sizes can be Sand used as the setting where suitable untreated compared with each other to bed should be a washed, materials are in short supply, An excess of fine particles select the best performing well-graded, sand with a although caution should be can increase the moisture sand. maximum size of about 3/16 used in specifying treated sensitivity of the bedding in. (4.8 mm). Sand con- soils. Their use should be sand. Bedding sands with Mason’s sand, limestone forming to ASTM C 33 based on local availability high fines content can lead screenings, or stone dust Specification for Concrete and experience. to rutting and movement should not be used as they do Aggregates is acceptable. forms of distress. It is not not compact uniformly, are Table 13 shows the grada- Aggregate subbase materials, only important to ensure normally too soft, and some tion limitations taken from as well as cement- and lime- that the fine content is sat- may cause efflorescence. ASTM C 33. In addition, the stabilized materials, are com- isfactory on the selected Soft materials, such as stone amount of material passing monly specified in local state bedding sand, but also that screenings, tend to break the 75 µm (No. 200) sieve and municipal standards for it will not break down under down over time into smaller should be limited to no highway construction. heavy traffic. A degradation particles. Cement should not more than 3 percent. The test can be undertaken on be added to the sand because sand particles should be the bedding sand to compare it makes removal and reuse of sub-angular. For pavements different bedding sand the pavers difficult, adds to subjected to heavy channel- options. The test involves the expense of the system, ized traffic, experience has rotating sand samples with a and may cause durability shown that only naturally problems.

23 Bituminous Setting Bed The bituminous setting bed system can be used as an alterna- TABLE 13: Gradation for tive to a sand setting bed system. The sand bed is replaced by Bedding Sand (ASTM C 33) an asphalt coated sand mixture that is bonded to the underly- Sieve Size Percent Passing, ing pavement layer with a tack coat. The brick pavers are in by Weight turn bonded on to this bituminous setting bed with a rubber- 9.5 mm (3/8-in.) 100 ized asphalt adhesive. 4.75 mm (No.4) 95 to 100 The most common material for the tack coat is an SS-1 or SS- 2.36 mm (No.8) 80 to 100 1h asphalt emulsion complying with ASTM D 977 Specification for Emulsified Asphalt. Typical application rates are 0.05 to 1.18 mm (No.16) 50 to 85 0.15 gallons per square yard (0.23 to 0.68 liters per square 600 µm (No.30) 25 to 60 meter) dependent on the surface texture and porosity. Graded 300 µm (No.50) 5 to 30 crushed aggregate base layers may require up to twice this rate. 150 µm (No.100) 0 to 10 75 µm (No.200) Less than 3 The asphalt cement for the bituminous setting bed should be the same grade as that specified for the surface course con- TABLE 14: Gradation for struction in the appropriate state department of transporta- tion or city highway specification. This may be a viscosity Bedding Sand in Channelized grade conforming to ASTM D 3381 Specification for Viscosity- Traffic Graded Asphalt Cement for Use in Pavement Construction (AC- Sieve Size Percent Passing, 10 or AC-20, and AR-2000 or AR-4000 are the most common) by Weight or a performance grade conforming to AASHTO MP 1 Specification for Performance Graded Asphalt Binder (designat- 3/8 in.(9.5 mm) 100 ed as PG grades that are dependent on high and low tempera- No.4 (4.75 mm) 95 to 100 tures in the area). The type of asphalt cement will govern the No.8 (2.36 mm) 75 to 100 mixing and rolling temperatures. The fine aggregate for the bituminous setting bed should be a natural or manufactured No.16 (1.18 mm) 55 to 90 sand that complies with ASTM D 1073 Specification for fine No.30 (600 µm) 35 to 70 Aggregate for Asphaltic Paving Mixtures, grading No. 2, or No.50 (300 µm) 0 to 35 similar material used as fine aggregate at the asphalt plant. All particles should pass the No. 4 sieve. A typical gradation is No.100 (150 µm) 0 to 5 shown in Table 15. No.200 (75 µm) 0 to 0.3

A local asphalt plant supplies the bituminous setting bed material. Generally only small loads, up to 5 tons (4.5 metric TABLE 15: Gradation for tons), are required at one time so that the work can be com- Bituminous Setting Bed pleted before the material cools and becomes unworkable. It is manufactured by combining the dried fine aggregate with Aggregate hot asphalt in the asphalt plant. The approximate proportions Sieve Size Percent Passing, are 6-8% of asphalt cement with 94-92% of fine aggregate or by Weight approximately 1 gallon of asphalt cement to 110 lbs of fine No. 4 (4.5 mm) 100 aggregate (1 liter to 13 kg). The exact proportions should be verified before supplying material for the project. The materi- No. 8 (2.36 mm) 75 to 100 als are mixed at a temperature of 300-325° F (149-163° C). No.16 (1.18 mm) 50 to 74 No. 30 (600 µm) 28 to 52 The adhesive is generally a neoprene modified asphalt product specifically developed for setting pavers. It consists of a rub- No. 50 (300 µm) 8 to 30 berized asphalt (typically 2% neoprene) with inorganic fibers No. 100 (150 µm) 0 to 12 (typically 10% non-asbestos fibers). However, other products including cold pour rubberized asphalt crack filling compounds No. 200 (7 µm) 0 to 5 have also proven to be successful.

24 Jointing Sand Jointing sand used between the brick For bituminous setting bed These products are a water pavers should generally have smaller systems it is necessary to repellent, applied to bind particles than the setting bed material provide stabilized joint jointing sand particles so that it completely fills the joints. sand as the joint sand is together. It is typically The sand particles should be sub-angular. not as well packed into the sprayed and squeegeed over joints. Without a stabilizer, the surface so that it soaks Pavers without lugs and with tighter dimen- creep can be excessive and into the joint sand and only sional tolerances may require finer jointing joint sand erosion is likely. a thin film remains. sand. Appropriate materials must be used to Mixtures of portland avoid sand wash-out or sand being sucked cement and sand have been Dry mix stabilizers are out by tires. Bedding sand (ASTM C 33) is used with varying success, mixed with dry jointing sand and swept into the recommended for joint filling in heavy but are not recommended. If such a mixture is used it joints. The binding mecha- vehicular pavements. However, the larger should consist of 1 part of nism is activated by applied particles often will not enter the joints portland cement and 6 water. In order to achieve Flexible Vehicular Brick Paving: Heavy Duty Applications Guide and should be swept off the surface. The parts of sand. The materi- satisfactory penetration and remaining sand particles require significant als are mixed dry before binding of the sand, it is encouragement to fully penetrate the joints. filling the joints, and are inappropriate to use the Success has been obtained by passing the brushed over the surface. ASTM C 144 manufactured sand when liquid polymer bedding sand through a No. 8 sieve. This The surface is fogged so that water penetrates the sealants are applied. This can be done at the jobsite or by the sand joints and hydrates the sand has a high percentage supplier before the material is delivered. cement. Staining or a of very fine particles which Mason’s sand may be used for lighter traffic resulting rigid system is prevent the penetration of conditions, and should be graded to the undesirable results of this the stabilizer to a satisfac- limits in ASTM C 144 Aggregates for Masonry practice. tory extent. The stabilizers should bind the sand in the Mortar shown in Table 16. The often rounded Liquid polymer sealants are top 1/2 in. (12 mm) of the shape of the finer grade mason’s sand proving to be more success- joint. makes it susceptible to removal from the ful than the sand cement joints. Thus, the use of stabilizers should mix. They can also be used be seriously considered. Other successful for areas subjected to sands have been specially graded, dried and heavy flows of water. bagged for joint filling. They are frequently available from some paver manufacturers. Limestone screenings or stone dust should TABLE 16: Gradation for not be used for the reasons listed under Jointing Sand (ASTM C 144) Setting Beds. Percent Passing,by Weight Sieve Size Natural Sand Manufactured Sand 4.75 mm (No.4) 100 100 2.36 mm (No.8) 95 to 100 95 to 100 1.18 mm (No.16) 70 to 100 70 to 100 600 µm (No.30) 40 to 75 40 to 75 300 µm (No.50) 10 to 35 20 to 40 150 µm (No.100) 2 to 15 10 to 25 75 µm (No.200) 0 to 5 0 to 10

25 TABLE 17: Brick Paver Types and Applications Flexural

ASTM Specification and Type Traffic Type Typical Applications Strength It is unlikely that a brick ASTM C 1272, Type F and R Heavy vehicular traffic Roadways,city streets, paver will ever fail in com- parking lots,ports pression (crushing) while in service. Instead, the criti- ASTM C 902, Type I High frequency pedestrian, Driveways,entranceways, cal property is the flexural light vehicles parking lots strength. A point load, such as a tire, transmits a ASTM C 902, Type II Intermediate frequency pedestrian Exterior walkways, force to the paver that is pedestrian plazas supported beneath by a uniform resisting load. The tion. ASTM C 1272 requires ability of a brick paver to Brick Pavers the brick to meet a mini- resist a point load is meas- mum compressive strength Brick pavers should conform to ASTM C 902 ured by either the modulus and a maximum cold water of rupture or the breaking Specification for Pedestrian and Light Traffic absorption. ASTM C 902 load. Each is evaluated Paving Brick or ASTM C 1272 Specification for pavers must meet a mini- according to ASTM C 67 Heavy Vehicular Paving Brick. The pavers mum compressive strength, Test Methods of Sampling are classified by the type of traffic they are a maximum cold water and Testing Brick and absorption, and a maximum subjected to during use. Structural Clay Tile saturation coefficient. (AASHTO T32.) In these Pavers covered by ASTM C Table 18 shows the physical Minimum tests an individual paver is 902 are intended to support property requirements for supported near its ends and pedestrian and light vehicu- the different classes of Thickness a downward force applied lar traffic with low volumes Brick pavers set in a sand paving brick. Paving brick midway between the two of traffic. The pavers can setting bed with sand subjected to freezing tem- supports. ASTM C 1272 be used in applications such between the pavers used in peratures should equal or establishes a minimum as residential patios and a heavy vehicular pavement exceed the physical proper- breaking load value shown driveways, sidewalks, require a minimum thick- ty requirements for ASTM C in Table 18. ASTM C 902 plazas, and commercial ness of 2-5/8 in. (67 mm) to 1272, Type R or F, or ASTM does not have requirements driveways. Pavers covered achieve interlock. This C 902, Class SX. for flexural strength. by ASTM C 1272 are intend- thickness is exclusive of any ed to support high volumes chamfers. Thinner pavers Because raw materials and of heavy vehicles. The will not provide interlock production methods for Abrasion heavy duty pavers can be and may move in place, brick vary throughout the Resistance used in applications such as allowing cracking of the country, it is difficult to use only the physical prop- Paving brick are exposed to roads, streets, and cross- pavers. The same thick- the abrasive effect of walks. Heavy vehicular nesses apply to pavers on erty requirements to classi- fy all brick. Therefore, pedestrian and vehicular traffic is defined as high bituminous setting beds. traffic. Of these two types volumes of heavy vehicles there are alternates which permit the use of those of traffic, pedestrian traffic representing trucks or com- Durability can cause the most wear of bination vehicles that have brick which perform satis- The durability of brick factorily in service but do the pavement surface. 3 or more loaded axles. A pavers is predicted by prop- Areas attracting concentra- possible measure of high not meet the physical erties such as compressive requirements listed in Table tions of pedestrian traffic, volume is over 25 ESALs per strength, absorption and such as doorways, gates, day or 200,000 ESALs over 18. Using the alternates in saturation coefficient. The ASTM specifications permits and even automatic teller the pavement life. Table 17 saturation coefficient, also machines, deserve special shows the traffic type and the use of brick that are referred to as the C/B ratio, known to perform well in attention. The high vol- applications for brick is the ratio of 24 hour cold ume and impact force of pavers. their intended application. water absorption to the 5 It does not signify that the high-heeled shoes cause hour boiling water absorp- brick are of a lower quality.

26 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 27 Dimensions associated the size and The of tolerances dimensional more brick are paving brick in flexible important than in other pavements applications. brick paving with accurate Pavers easier for are dimensions lay with to installer the between spacing adequate faces. Other tests, such as such tests, Other faces. the allow trailer, fixed the of sections larger of testing into that take pavements aspect positive the account of joints. skid resist- the time, Over surfaces all paving of ance the of because decreases traf- the effect of polishing skid resistance The fic. brick is ini- most for value high and tially very in use, while decreases an equilibrium approaching months several condition skid The after placement. also are values resistance seasonal fac- affected by British Pendulum The tors. the measure can also Tester (PPV) Value Paver Polished has been in paver after the service. a 18 nts, a 16 resistant surface that caus- surface resistant the Since falls. es many on the relies slip resistance paving the of microtexture brick, a brick with a surface cut wire rougher slip a higher will have value. resistance measures Skid resistance vehicles of potential the roadway on the skidding relatively the For surface. on speeds expected slow brick paveme flexible depends skid resistance the of microtexture upon the Joints surface. paver the and pavers the between have also edges chamfered effect on the a positive A skid resistance. overall friction tester is pendulum skid resist- measure to used tester, pendulum The ance. for ASTM E 303 Method Surface Measuring Using Frictional Properties British Pendulum the wet the measures Tester, of value skid resistance pavers. individual unused brick new for values Typical British the from pavers from range Test Pendulum to pavers smooth 50 for sur- wirecut 80 for over a 3,500 (24.1) Slip and Skid Resistance a of slip resistance The to is related surface paving while traffic, pedestrian to is related skid resistance slip The traffic. vehicular are skid resistance and slipperi- the of measures A sur- a surface. of ness a high slip or with face is relatively skid resistance may value a low while safe, sur- a hazardous indicate face. is adversely Slip resistance on the water affected by pavement. the of surface walking surprise of is the It surface a slip resistant from or nonslip a wet onto The volume abrasion loss is loss abrasion volume The a submitting by determined sandblasting the to paver two of a duration test for and rate flow The minutes. sand the of limits grading ASTM C from differ slightly is loss volume 418. The the filling by determined with depression abraded calcu- then clay, modeling dur- lost volume the lating sandblasting. ing a Average of 5Average Individual Avg.of 5 Individual Avg.of 5 Individual Avg.of 5 Individual 4,000 (27.6) lower skid resist- lower

and Type Strength,psi (MPa) lb./in.(kN/mm) Absorption,% Coefficient

C 1272, F Type 10,000 (69.0) 8800 (60.7) 475 (83) 333 (58) 6 7 None None C 1272, R Type 8,000 (55.2) 7,000 (48.3) None None 6 7 None None

C 902, Class SX (55.2) 8,000 7,000 (88.3) None None 8 8 0.78 0.80 C 902, Class MX 3,000 (20.7) 2,500 (17.2) None None 14 17 None None

Molded Brick ASTM Specification Compressive Minimum Load Minimum Breaking Water Maximum Cold Maximum Saturation with in-field performance. with in-field index has correlated well has correlated index purposes. The abrasion The purposes. calculated for durability for calculated absorption tests must be must absorption tests compressive strength and strength compressive expedient measure since measure expedient The abrasion index is an index abrasion The brick are listed in Table 19. listed in Table brick are requirements for paving for requirements Sandblasting. The abrasion The Sandblasting. Resistance of Concrete by Concrete of Resistance Method for Abrasion for Method with ASTM C 418 Test abrasion loss in accordance loss abrasion determining the volume the determining tiplying by 100, or 2) by by tiplying sive strength and then mul- then and strength sive absorption by the compres- the absorption by by dividing the cold water cold the dividing by abrasion index is calculated index abrasion in one of two ways: 1) an ways: two of in one brick pavers is determined brick pavers The abrasion resistance of resistance abrasion The ance value. value. ance a slightly a slightly tire traffic which results in which results traffic tire will polish with repeated are permitted. Brick roads are effect, unless studded tires studded effect, unless not have such a drastic such have not sion. Tires on roadways do on roadways sion. Tires the highest degree of abra- of degree highest the

a TABLE 18: Physical Requirements for Brick Pavers for Brick Requirements Physical 18: TABLE TABLE 19: Abrasion them. These joints, formed service. This may reduce Requirements for Pavers by the careful placement the amount of chippage on Paver Specification Abrasion Index Volume Abrasion Loss of each unit, ensure inter- the paver. Lugs are usually and Type (Max) (Max) (cm3/cm2) lock and reduce chippage necessary when the pavers of pavers. are subjected to heavy ASTM C 1272, Type R and F 0.11 1.7 vehicular traffic. When ASTM C 902, Type I 0.11 1.7 Commonly available sizes lugs are on only one side of pavers for flexible pave- or one end of the paver, ASTM C 902, Type II 0.25 2.7 ments are listed in Table they are included when 20. The edges of pavers measuring the length or may be square or may have width. This approximates a small chamfer or rounded the dimensions between edges. When chamfers are the centers of the joints. HEIGHT present it is recommended When lugs are included on that they not exceed 3/16 both sides and both ends of in (5 mm) in depth or the paver, the lugs share width. The minimum the space between the LENGTH height of the paver neces- pavers. Thus, only one lug WIDTH sary for interlock does not CHAMFER is included when measuring include the height of any the length or width of the HEIGHT chamfer. The top edges of paver. pavers with chamfers or LUGS rounded edges are less The dimensional tolerances likely to touch during for pavers are shown in LENGTH compaction or in service, Table 21. For flexible pave- WIDTH reducing the potential for ments subjected to vehicu- chipping. lar traffic, ASTM C 1272, Type F or ASTM C 902 TABLE 20: Common Sizes of Brick Specially-shaped pavers are Application PX is recom- Paversa available from some manu- mended. Brick with larger Width,in.(mm) Height,in.(mm) Length,in.(mm) facturers lending a decora- dimensional tolerances will tive effect to the pave- be difficult to install, espe- 4 (102) 2 1/4 (58) 8 (203) ment. The shape, other cially with herringbone and 4 (102) 2 3/4 (70) 8 (203) than the ratio of maximum basketweave patterns, and length to thickness, has no 4 (102) 3 (76) 8 (203) may not provide interlock. measurable effect on the 3 5/8 (92) 2 1/4 (57) 7 5/8 (194) interlock between the a Check with manufacturer for availability of chamfers and lugs. pavers or on the strength Other of the pavement. Pavers should be dimensioned so Materials that the ratio of maximum TABLE 21: Dimensional length to thickness is less Surface Tolerances for Pavers than 3 to 1. Coatings Maximum Permissible Variation,in.(mm) ± Some pavers also are made Colorless coatings (i.e. Paver Specification < 3 in. Over 3 to 5 in. Over 5 to 8 in. Over 8 in. with lugs or spacers. water repellents) are gener- and Application (76 mm) (76 to 127 mm) (127 to 203 mm) (203 mm+) These lugs, usually 1/8 in. ally not recommended on ASTM C 1272, 1/8 (3.2) 3/16 (4.8) 1/4 (6.4) 5/16 (7.9) (3 mm), space the pavers exterior brick pavements. Application PS apart and provide a uni- The wrong type of coating may not permit vapor ASTM C 1272, 1/16 (1.6) 3/32 (2.4) 1/8 (3.2) 7/32 (5.6) form gap for jointing sand. transmission (evaporation) Application PX The lugs also keep the paver edges from touching and may trap water within ASTM C 902, 1/16 (1.6) 3/32 (2.4) 1/8 (3.2) 7/32 (5.6) during compaction and in a paver. This may lead to Application PX

28 damage due to freeze/thaw ed area a sufficient dis- or spalling of the face due tance to cover the base to build up of crystalline material. They should deposits of soluble salts or overlap approximately 24 ice beneath the coating. to 36 in. (610 to 914 mm) Non-penetrating type coat- to maintain strength. Only ings will wear off quickly in woven geotextiles should high traffic areas. be used directly under the bedding sand, as this loca- However, coatings that pre- tion is highly abrasive, and vent erosion of the jointing can separate the fibers on sand may be beneficial. In non-woven materials. that case, the coating should be of a type that has a high vapor transmis- Edge sion rate, and will not Restraints affect the slip/skid Edge restraints are manda- Flexible Vehicular Brick Paving: Heavy Duty Applications Guide resistance of the paver. tory in flexible brick The stabilizer should be pavements. Edge restraints water based. hold the pavers together and provide for interlock of Geotextiles the wearing surface. Many Geotextile fabric materials different types of edge can be used to separate restraint materials exist, layers of materials in the including brick, rigid plas- paving system. Geotextiles tic, wood, steel, aluminum, can also be used as a filter or concrete. The type of material in many drainage application determines applications. Subgrade soil which material to use. Any can be prevented from of the materials listed can migrating into the base or be used in pedestrian appli- subbase by use of a geotex- cations. Only concrete, tile. Other uses of geotex- brick placed in concrete, tiles range from providing some varieties of rigid plas- erosion control to being tic, or steel edgings should used to reinforce subgrade be used in areas subjected beneath the pavement by to vehicular traffic. In adding strength to the sys- heavy vehicular applica- tem. Geotextile manufac- tions, only cast-in-place turers should be consulted concrete should be used. to determine applicability Flexible pavement materi- of geotextiles in flexible als, such as brick set in brick paving applications. sand, loose aggregates, or The recommended minimum asphalt, are not suitable as apparent opening size of edge restraints. the geotextile should be No. 70 (0.2 mm). The geotextile fabric may be either woven or nonwoven, and should be placed so that the material extends up the side of the excavat-

29 Part III: Construction

appropriate choice of of Soils and Soil- Introduction compaction equipment. Aggregate Mixtures Subgrade preparation is Using 10 lb. (4.5 kg) The in-service performance of the pavement commonly specified in Rammer and 18 in. depends on the preparation and installation of local state and municipal (457 mm) Drop. the underlying materials. If the materials are standards for highway The latter of these tests not placed and compacted properly, then the construction. It is also is normally used to test entire brick pavement system may not perform likely that the geotechnical materials that support as intended. Properly sized joints between report will provide recom- heavier loads for higher pavers, completely filled with jointing sand, mendations on minimum shear strength. compaction standards. are essential to complete interlock and for Field tests which long term performance. Various tests are used determine soil density to determine the proper provide a method to check To achieve the best compaction and density for conformance to job Subgrade performance from the of the soil. Laboratory specifications. Three field The subgrade is excavated, subgrade it is necessary compaction tests to tests are often used: if necessary, to achieve the to scarify the top surface, determine proper placement • Sand Cone Test, ASTM D required finished level. condition it to the proper requirements include: moisture content, and then 1556 (AASHTO T191) Test Any unsuitable material, • Standard Proctor Test, Method for Density and to recompact it to estab- such as organic material, ASTM D 698 Methods for Unit Weight of Soil in lished relative densities. large rocks, etc., should be Laboratory Compaction Place by the Sand Cone removed from the subgrade The moisture content of Characteristics of Soil Method. and replaced with suitable the soil must be within Using Standard Effort • Water Balloon Test, ASTM allowable limits of the (12,400 ft-lb/ft3 (600 backfill. The subgrade D 2167 (AASHTO T205) optimum moisture content kN-m/m3)) or AASHTO should be drained and Test Method for Density protected against flooding and be carefully monitored T9 Test Methods for Moisture-Density and Unit Weight of Soil in and ground water by to achieve maximum Relations of Soils and Place by the Rubber sub-soil drainage. The compaction. The subgrade Soil-Aggregate Mixtures Balloon Method; and installation of pipes and soil should be compacted to at least 95% maximum Using 5.5 lb. (2.5 kg) • ASTM D 2922 (AASHTO sub-soil drainage should Rammer and 12 in. density if they are granular T238) Test Methods for be completed before initiat- (305 mm) Drop; and and to at least 90% Density of Soil and Soil- ing the base or subbase Aggregate in Place by construction. The width maximum density if • Modified Proctor Test, ASTM D 1557 Test Method Nuclear Methods (Shallow of the subgrade should be they are cohesive. The for Laboratory Compaction Depth). sufficient to extend to the method of compaction Characteristics of Soil It is important to back edge of the proposed and compaction equipment may vary due to soil type Using Modified Effort remember that the edge restraint or abut (56,00 ft-lb/ft3(2,700 and size of area being maximum density varies existing structures. kN-m/m3)) or AASHTO compacted. Figure 9 is between samples, and so T180 Test Methods for proper soil identification a general guide to the Moisture-Density Relations

30 SOIL

NON-COHESIVE PERCENT MIX COHESIVE SAND SAND & CLAY CLAY

100% 75 50 75 100% RAMMERS

RAMMER PLATES

RAMMER WITH EXTENSION PLATES

VIBRATORY PLATES is required to establish the appropriate target density for VIBRATORY ROLLERS each location. STATIC ROLLERS Because brick paving is frequently used as hard landscaping adjacent to major building projects, it is often the case VIBRATION RAMMING that designers are not familiar with highway testing and REQUIRED REQUIRED Flexible Vehicular Brick Paving: Heavy Duty Applications Guide construction procedures. Therefore, great care must NORMAL RANGE be taken in evaluating and testing the subgrade. For best results then, follow the procedures outlined in this Guide TESTING RECOMMENDED along with the advice of a pavement design professional. Figure 9: Soil Compaction Guide

Compaction should be completed as soon as possible after the Subbase material has been mixed and spread. The profiles should be This Guide considers various types of subbase material as such that water is channeled towards drainage facilities. set out in Table 7 and the associated text. These include graded aggregate, cement- and lime- stabilized soils. Basic assumptions on the types of materials are in the table. Base Subbase courses should be designed following Part I of this The design tables in this Guide provide options for various Guide, or guidelines and specifications of local authorities. types of base course material. These include graded aggre- gate bases, cement-treated bases, and asphalt-treated bases. Geotextile fabric may be used to separate the subgrade soil Thickness of portland cement concrete slabs on an aggregate from an aggregate subbase, especially in soils subject to subbase is also considered. Details can be found in Table 7 moisture levels near or at saturation. The geotextile will and the associated text. Base courses should be designed prevent intrusion of the subgrade soil into the bottom of following Part I of this Guide, or guidelines and specifications the aggregate subbase or vice versa. They must be placed of local authorities. without wrinkles and lapped at their edges. Geotextile fabric may be used to separate the subgrade The aggregate subbase course materials should be spread soil from the compacted base, especially in soils subject and compacted in layers. In-place mixing and compaction to moisture levels near or at saturation. The geotextile will of the stabilized materials can be carried out, or mixing prevent intrusion of the subgrade soil into the bottom of the can be undertaken remotely and the mixture spread and aggregate base or vice versa. They must be placed without compacted in layers. The thickness of these layers must wrinkles and lapped at their edges. be consistent with the capabilities of the compaction equipment. All subbase materials should be compacted The base course materials should be spread and compacted to a minimum of at least 95 percent of maximum density. in layers. The thickness of these layers must be consistent The subbase should also extend at least one layer thickness with the capabilities of the compaction equipment. See past the edge of the overlying layer to enable adequate Figures 10, 11 and 12. All base materials should be compact- compaction at the edges of the pavement. Typically, the ed to a minimum of 95 percent maximum density. The base thickness of each layer is approximately 3 to 4 in. (76 to should also extend at least 6 in. (150 mm) past the edge 102 mm), but can increase to double these thicknesses if restraint if spikes are used to hold the restraint in place. appropriately heavy compaction equipment is used.

31 Typically, the thickness of each layer is approximately 3 to 4 in. (76 to 102 mm). The surface of the base should be close-knit to pre- vent setting bed material from filtering downwards through the base. It must be of good quality to avoid failure due to high stress concentrations immediately under the wearing surface.

Compaction should be com- pleted as soon as possible after the material has been spread. It is essential that the intended surface profile of the base be formed so that the pavers can be placed on a uniform thick- ness of bedding sand.

Figure 10: Leveling Base Sand Setting Bed The sand setting bed material is spread over the base in a uniform thickness. The setting bed is not meant to, and should not, be used to fill in low spots or bring the pavement to the correct grade. The thickness of the setting bed should be 1 in. (25 mm) thick with a tolerance of plus or minus 3/16 in. (5 mm) Setting bed thicknesses that are excessive could lead to shifting of the setting bed material, causing loss of strength.

The sand is typically spread over the base between 1 in. (25 mm) diameter screed rails. These are set to a pro- Figure 11: Proper Base Compaction 32 file to provide sufficient depth in the uncompacted bedding layer, to account for the reduction from compaction. Screed rails are typically placed 8 to 12 ft. (2.4 to 3.7 m) apart, and at closer centers when a changing grade is required. There are several specialized screeding systems that enable more rapid installation and result in less foot traffic on the sand. On some large projects, asphalt paving machines have been Flexible Vehicular Brick Paving: Heavy Duty Applications Guide used to spread the sand.

The setting bed sand should not be spread too far in front of the laying face of the pavers to prevent dis- turbance. The sand should be screeded without com- Figure 12: Compacting Near Edge paction to a level slightly dry to the touch) before higher than the final thick- being saturated. Water and moisture protection. applying the bituminous ness of the layer. The sand should not be added to The tack coat will generally setting bed. should be disturbed as little screeded sand except as a be supplied to the site as possible since the final very light misting. in drums or pails due to pavement surface will the limited area at any A local asphalt plant Stockpiled material should supplies the bituminous reflect any variation. The be kept covered. application time. The air voids left by the screed rails and substrate temperature setting bed material. Generally only small loads, should be filled from the The screeded bedding sand should be above 50°F up to 5 tons (4.5 Mg), paver laying face as work is vulnerable to environ- (10°C). The material are required at one time progresses. The common mental disturbance from should be at a temperature so that the work can be practice of filling from the wind or rain. Care needs of about 80°F (27°C) or completed before the screeding side can leave to be taken so that water above when applied. A material cools and becomes localized areas of over com- cannot drain back into the continuous, uniform coat unworkable. The materials pacted sand, which results bedding sand when it is should be applied by are mixed at a temperature in subsequent high spots. uncovered or covered with spraying, squeegeeing or of 300 to 325°F (149 to If the sand is disturbed, the pavers but not vibrated. brushing the material. area should be rescreeded. Typical application rates 163°C). The mixed materi- Prepared areas should not are 0.05 to 0.15 gallons al should be delivered to be left overnight, unless Bituminous per square yard (0.19 to the site in an appropriate they are properly protected 0.57 liters per square covered truck. The truck from disturbance and mois- Setting Bed meter), depending on bed should be steel that is ture. The moisture content surface texture and clean and a lubricant The first step in of the setting bed sand porosity. Work should should be used to help with constructing this system should be as uniform as not be carried out in rainy discharge. is to apply a tack coat possible, and the material conditions. The tack coat over the base layer to Steel screed rails, typically should be moist without must cure for 1/2 to 1 hour achieve a level of bonding 12 ft. (3.7 m) long, are set (until it turns black and is

33 up on timber packs to achieve a uniform profile. These are typically at 10 to 12 ft (3 to 3.7 m) centers, oriented along the profile of the street. When establishing the profile, it Paver Installation is important to allow for the likely compaction of the set- ting bed. The hot material is spread over the surface of General the tack coat and screeded off to a nominal thickness of Work may start from an exact edge or from 3/4 in. (19 mm). Care should be taken to ensure that the centerline of the pavement. The pavers release agents applied to the screed rails and tools do not should be laid in the desired bond pattern, cause damage to the bituminous setting bed. The screeded with a joint width between 1/16 in. (2 mm) panels are advanced down the street as each screed rail 3 length is completed. To minimize foot traffic on the and /16 in. (5 mm) on all sides. Pavers with screeded material, alternate panels are constructed so that square edges or without lugs, should not be the screed rails and timber packs can be removed and the forced together or laid “hand tight”, as this infill panel screeded using the edges of the two outside can result in excessively tight joints, which panels. The infilling of narrow slots where screed rails may cause the pavers to chip during installa- have been removed should be minimized, as this can result tion, compaction or service. Pavers with lugs in a variable density and differential compaction. Screeding should be undertaken while the material is still hot. provide the correct gap when they are placed Particles of colder material will drag under the screed rule in contact with each other. and result in a rough surface. As the layer is thin it will cool quickly. Once the asphalt sand mixture has cooled to a suitable temperature it is rolled to provide a smooth, uni- String lines or chalk lines with pavers cut to size. All form surface. A walk-behind or small ride-on steel drum may be used to keep the pavers should be cut with a roller, with a weight of 200 to 300 lbs per ft (300 to 450 pattern straight. It may be masonry saw to produce an kg per m) width of drum, should be used. On small proj- necessary to slightly alter accurate, clean cut. The ects and in confined locations, a vibratory plate compactor the pattern module to blade should have a soft may be used. accommodate the exact bond matrix and a high There are two different degrees of compacting the bitumi- dimension of the pavers. diamond concentration in nous setting bed. In one, the bituminous setting bed is Straight and true bond order to cut clay pavers laid and lightly compacted with the roller. This results in lines are necessary in areas effectively. A trial area a setting bed with an open texture and high void content. subjected to heavy vehicu- may be laid out in advance In the second system, the bituminous setting bed is more lar traffic to provide a uni- of work to determine paver thoroughly compacted during the rolling process. This form distribution of hori- positions to minimize the results in a more closed surface with less texture. zontal loads. The spacing amount of cutting and of the string lines should maintain cut pieces of suf- be based on the contrac- ficient size. A rule of tor’s experience, size of the thumb is to have the mini- project and speed of lay- mum face dimension of the ing. It is inadvisable to cut piece not less than the open joints above 3/16 in. paver thickness. It is com- (5 mm) to avoid cutting at mon practice to run one or an edge. The wider joints two rows of pavers laid in are likely to lead to greater stack bond (sailor course) creep and a reduction in along edge restraints. This structural integrity. facilitates subsequent cut- ting of pavers and ensures Whole pavers should be that the cut is between laid first, followed by cut similar materials. pavers. After the area is laid with whole pavers, it A herringbone pattern laid is easy to fill in the spaces at 45° or 90° to the edge

34 17 16 15 14

123 4567 8 9 10 11 12 13

Figure 13: 45° Herringbone Installation Pattern Flexible Vehicular Brick Paving: Heavy Duty Applications Guide

NOSE OF PAVERS

CHALK LINE

7 8 9 3 10 4 11 1 5 12 2 6 13

Figure 14: 90° Herringbone Installation Pattern of the pavement should be perpendicular to the flow of Felt or other geotextiles quent passes of the com- used for vehicular applica- traffic. In all cases, the should not be placed pactor, jointing sand is tions. A 45° herringbone bond pattern should be directly beneath the brick spread across the surface may be started along an checked periodically to pavers. Felt does not allow before compaction, as edge and continue parallel ensure proper alignment. interlock, since the setting shown in Figure 16. The to that edge. See Figure Slight adjustments can be bed is not allowed to inte- jointing sand should be 13. A 90° herringbone made in the thickness of grate with the jointing dry and spread on the should be started, if possi- the joint, since it is far sand between the pavers pavement until the joints ble, at an exact corner or easier to replace a row or during compaction. After appear full. If movement the centerline of the area two of pavers than to the pavers have been of the pavers occurs as a to be paved. Otherwise, a reconstruct an entire area. placed on the sand setting result of wide joints adopt- “pyramid” of pavers should bed, the brick pavement is ed when the bricks do not be advanced over the area Pavers on vibrated by a mechanical have spacers, a light distri- along a line, as in Figure plate vibrator/compactor. bution of bedding sand 14. If a running bond Sand Setting The first pass is done with- over the surface before pattern is used, the pavers Bed out jointing sand spread on vibration can be beneficial. should be laid so that the surface, as shown in If chipping of the pavers The installer works off of their long dimension is Figure 15. Prior to subse- occurs, laying geotextiles the pavers already in place.

35 and the quantity of adhe- sive can be better con- trolled. Troweling is typi- cally used to spread it. The pavers are then set close to their final posi- tion, as they become diffi- cult to move when the adhesive hardens.

The adhesive can be cold applied, but should be above 70°F (21°C) for best results. It is applied at a coverage rate of 30 to 50 sq ft per gal (0.84 to 1.2 sq m per liter), by brush, squeegee or trowel, depending on its viscosity. The adhesive should be spread at least two hours before setting the pavers.

The brick pavers are placed by hand onto the adhesive. The installer works off of Figure 15: Compaction of Brick Pavers, with Protection the pavers already installed. They are placed with joint widths of 0 to material on the surface lbs. (13.3 to 22.3 kN) of press the lightly compacted 1/16 in. (1.6 mm) to the before vibration can be centrifugal force. setting bed and squeeze correct laying pattern, and beneficial. Obviously the Compaction should not the adhesive back to the aligned as soon as possible initial vibration and place- occur within 6 ft (2 m) of interface between the set- to form straight lines. ment of the jointing sand any unrestrained edge. ting bed and the pavers. Wider joints should be dis- should be accomplished as This achieves a good bond couraged and the pavers soon after placing the and full coverage of the Pavers on should be placed as close pavers as possible and bottom of the paver. It is together as possible while before any traffic is permit- Bituminous good practice to roll the maintaining the alignment. ted on the paving. surface of the completed Setting Bed When the pavers have lugs, paving with a heavy rubber A plate compactor with a The pavers are set on an they may be placed in tire roller. This will high frequency/low ampli- adhesive spread on the contact with each other enhance the compaction tude plate, equipped with a bituminous setting bed. for best results and to of the bituminous setting rubber mat or a rubber- When the setting bed is minimize creep. bed if the pavement is to roller mechanical vibrator, lightly compacted, the be used by heavy vehicles, is used. Use of a steel adhesive drains down into Traffic should not be per- reducing the likelihood drum roller is likely to the surface texture of the mitted on the paving until that rutting will develop cause some cracking of the setting bed. With the light the joints are filled with in the wheel paths. bricks. If it is used in compaction the pavers are jointing sand that is stabi- typically loose at first so lized. The preferred vibration mode, significant When the setting bed is they can be aligned. When method is to use dry sand damage can occur. The highly compacted, the the pavement surface car- and a stabilizer. Dry joint plate area should not be adhesive does not pene- 2 2 ries traffic, the pavers com- sand is brushed into the less than 2 ft (0.19 m ) trate into the setting bed and produce 3,000 to 5,000

36 and hydrates the cement. It is possible that some set- tlement of the joint filling material will occur so that a second treatment may be required. Care must be taken to ensure that no cement is left on the pave- ment surface as stains may result. This is particularly difficult if the pavers have a rough surface texture or are engraved. Tolerances Flexible Vehicular Brick Paving: Heavy Duty Applications Guide The final surface elevation should be left slightly above adjacent pavement to allow for secondary com- paction of the bedding layer under traffic. It is typical for an additional 1/8 in. (3 mm) of compaction to occur, but local experi- ence should govern. The maximum variation in level should be within ±3/16 in. in 10 ft (± 5 mm in 3 m). Pavers adjacent to drainage inlets and channels should be left slightly higher, but Figure 16: Sweeping Joint Sand not more than 3/16 in. (5 mm) above it. The edges joints in the same manner applied after the dry sand to settle to encourage com- of any two adjacent pavers as for sand set systems. is brushed into the joints plete filling of the joints. should not differ more than No vibration is used. and the excess swept However, the moisture 1/8 in. (3 mm) if the pavers When the joints are full, off. It is sprayed and should be allowed to dissi- have chamfers, or 1/16 in. the sand is swept off so squeegeed over the surface pate prior to applying liq- (1.6 mm) if they have that it is level with the so that it soaks into the uid stabilizer. square edges. Paver to bottom of the chamfers or joint sand and only a thin paver tolerances are meas- the top of the pavers. If a film remains on the sur- An alternative, and not ured either chamfer to dry stabilizer is used, it is face of the pavers. It is recommended process, is chamfer or top edge to top mixed with the dry sand important that the stabi- mixing cement with dry edge. The bond line to prior to application. The lizer is water based as sol- joint sand and brushing it which the paver pattern is dry stabilizer is activated vents can harm the adhe- into the joints. No vibra- laid also has dimensional with applied water to bind sive and setting bed mate- tion is used. When the tolerances. These should be the sand particles. A liq- rials. It is possible to wet joints are completely filled, within ± 1/2 in. in 50 ft (± uid joint sand stabilizer the surface of the pavers the surface of the pavers is 10 mm in 15 m). that binds the sand parti- or allow time for the sand lightly misted so that the cles together, if used, is water penetrates the joints

37 priate to set the pavers Snow In Service high of the final surface so as to accommodate any Removal Considerations consolidation. Providing a Snow removal from brick slight arch to the profile pavements should not Surface Coatings will help in maintaining present any particular Colorless coatings, i.e. water repellents, are generally a good fit. problem. It can be not recommended on exterior brick pavements. See the removed by plowing, discussion in Part II: Materials. If surface coatings are to Maintenance blowing or brushing away be applied, the manufacturer’s instructions for applica- the snow. When using Although brick paving tion should be followed. plows or shovels there are surfaces are very durable, precautionary measures some routine maintenance that can be taken to Repairs may be necessary. At some time during the life of a flexible brick pavement, preserve the surface repairs or utility work beneath the pavement may require character of the brick. the removal and replacement of pavers from the working Efflorescence Metal blades should be area. When starting repairs, a single brick should be Efflorescence, a white rubber or urethane tipped removed, preferably with a purpose-made tool. It may powdery substance or mounted on small be necessary to break a few pavers to start the removal. produced by soluble salts, rollers. The blade edge Adjacent pavers are then removed and stacked nearby may be unavoidable on a should be adjusted to a to be used again if not damaged. The pavers should be paving surface. Deicers clearance height suitable cleaned of adhering sand by brushing. Cleaning of used on adjacent areas for the pavement surface. asphaltic material is usually difficult, and it may be may be deposited onto the When hand shoveling, necessary to remove pavers set on bituminous setting brick pavement, soluble shovel at an angle to beds from the site for cleaning with a solvent. salts may be present within the paver edge to avoid Temporary edge restraints should be placed at the paving system components, catching it. Avoid the perimeter of the removal area. or salts may migrate from use of any chemicals adjacent soils. Therefore, containing rock salt Excavation of trenches should follow established proper drainage and (calcium chloride) to procedures. Proper compaction of the returned fill maintenance are especially aid in melting ice. material is very important. If the area is too small for critical to reduce the Use of these materials proper compaction, stabilized materials, such as concrete, amount of efflorescence. may cause efflorescence. should be used. The compacted fill should be brought up If efflorescence does Calcium magnesium to the proper level. One or two feet (0.3 to 0.7 m) of appear on the paving acetate is recommended pavers around the perimeter of the excavated area should surface, natural weathering for snow and ice removal. be removed so that accurate levels can be established or traffic will usually Urea is used to melt ice at from undisturbed work. At all times, vehicular traffic eliminate it. Efflorescence many airports without should be kept at least 6 ft (2 m) away from the work should not be removed causing efflorescence, but edges. from the surface with it is not effective below acids. There are 20 °F (-7 °C). Otherwise, Setting bed material should be screeded to the proper proprietary efflorescence remove snow before it can grade. The setting bed should be compacted and a thin removers available. be compacted or turn to layer of sand screeded on top. Temporary edge restraints ice. To render icy surfaces are removed and the pavers are then laid in the correct passable, use clean sand bond pattern. Some creep of the pavement may have or ashes on the icy areas. occurred during repairs; therefore, some pavers may have to be saw cut to fit. Jointing sand should be spread over the top of the pavers and the system vibrated to the fin- ished level with a plate compactor. Two or three passes may be necessary to fill the joints. Dependent upon the type of backfill used in the excavation, it may be appro-

38

Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 39

when available. when materials and local experience should be applied should experience local and materials related construction materials. Information on local on local Information materials. construction related and a basic understanding of the properties of brick and of properties the of a basic understanding and be used in conjunction with good engineering judgment engineering with good in conjunction be used The information and recommendations in this Guide must in this Guide recommendations and information The are similar to those used for other pavements. pavements. other for used those similar to are and construction procedures recommended in this Guide in this recommended procedures construction and properly performing flexible brick pavement. The materials The brick pavement. flexible performing properly information on how to design, construct and specify a and construct design, to on how information a fairly new concept. This Guide provides designers with designers provides This Guide concept. new a fairly flexible brick pavement for heavy vehicular applications is applications vehicular heavy for brick pavement flexible however, the design and construction of an interlocking of construction and design the however, Closing Closing centuries, material for as a paving Brick has been used References Appendix A 1. American Association of State Highway and Transportation Officials, Guide for Design of Pavement Definitions of Terms Structures, Washington, D.C., 1993. AASHTO (American Association of State Highway and Transportation Officials): National association of highway 2. Brick Development Association, BDA Design Note 9, officials. Flexible Paving With Clay Pavers, United Kingdom, Oct. 1988. Base: The layer or layers of specified materials of designed thick- ness placed on a subbase or a subgrade to support the wearing 3. Brick Industry Association, Flexible Brick Pavements: surface. Heavy Vehicular Pavements, Design and Installation Guide, CBR (California Bearing Ratio): A measure of the shear Reston, Virginia, 1991. strength or stability of a soil or granular material, expressed as a percentage of the strength of a standard material and measured 4. Clay Brick and Paver Institute, Paver Note One, Specifying by a constant rate of strain penetration machine either in-situ or and Laying Clay Pavers, Australia, Aug. 1989. in a laboratory.

5. Clifford, J.M., Segmental Block Paving in Southern Africa - Cement Lime-Stabilization: A technique that improves the A Review and Structural Design Guide, National Institute strength or stability of clay soils (subgrades) by the incorporation of portland cement or lime. for Transport and Road Research, Republic of South Africa, Sept. 1986. Compaction: The process that consolidates the subgrade, subbase or base; the process by which the brick pavers are settled into the 6. Knapton, J. and Barber, S.D., UK Research into Concrete setting bed during construction and jointing sand is vibrated into Block Pavement Design, 1st Concrete Block Paving the joints between the pavers to create interlock. Conference, Newcastle-upon-Tyne, United Kingdom, 1982. Creep: Horizontal movement of the brick pavers generally caused by the braking actions of vehicular traffic. 7. Knapton, J. and Mavin, K.C., Design Manual 1, Clay Segmental Pavements, Clay Brick and Paver Institute, Edge Restraint: Resistance to horizontal movement at the edge Australia, Jan. 1989. of the pavement provided by sufficiently rigid supports.

8. National Stone Association, Flexible Pavement Design ESAL (Equivalent Single Axle Load): The representation of the Guide for Roads and Streets, Jan. 1985. passage of an axle of any mass (load) by a number of 18-kip (80 kN) equivalent single axle loads. 9. Pavement Consultancy Services, Structural Design of Frost Heave: Localized volume changes that occur in the Roads and Streets using Concrete Block Pavements, roadbed soil as moisture collects and freezes into ice lenses. National Concrete Masonry Association, Herndon, VA, Jan. 1989. Geotextile Fabric: Any permeable textile material used to sepa- rate pavement layers. 10. The Total Concept, Blockleys, plc, United Kingdom, 1988. Heavy Vehicular Traffic: Traffic consisting of high volumes of 11. Understanding Soil Compaction, J.I. Case Co., Racine, WI, heavy vehicles. Heavy vehicles are considered trucks. 1988. Herringbone: A bonding pattern with alternate pavers at right angles to each other forming a zigzag effect. Generally recom- 12. Walsh, I.P., A Comparative Field Study of the Performance mended in vehicular traffic applications. of Brick Pavers, Chemistry and Industry, Nov. 1985. Interlock (Lock-up): The effect of frictional forces, induced by sand beneath and between the brick pavers that inhibits move- ment of the paver and transfers loads between adjacent pavers.

Layer Coefficient: The empirical relationship between structural number (SN) and layer thickness that expresses the relative abili- ty of a material to function as a structural component of the pavement structure.

40 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 41 )) 3 )) 3 (2,700 kN-m/m (600 kN-m/m 3 3 Binder Sandblasting by Concrete Brick Paving (12,400 ft-lb/ft Paving Mixtures Paving (56,000 ft-lb/ft (Shallow Depths) (Shallow or Airports Highways Bases or Subases for Construction in Pavement Use for Cement Tester British Pendulum the Using Properties Appendix B Appendix Standards Referenced MPIAASHTO Asphalt Graded Performance for Specification ASTM C 33ASTM C 67 T32)(AASHTO Aggregates Concrete Specification for Clay Tile ASTM C 144 Structural and Brick Testing and Sampling of Methods Test ASTM C 418 Masonry Mortar for Aggregates Specification for of Resistance Abrasion for Method Test ASTM C 902 Traffic Light and Pedestrian for Specification ASTM C 1272ASTM D 698 Brick Paving Vehicular Heavy for Specification T99)(AASHTO Compaction Laboratory for Methods Test Effort Standard Using Soil of Characteristics ASTM D 977ASTM D 1073 Asphalt Emulsified for Specification Asphaltic for Aggregate Fine Specification for ASTM D 1556 T191)(AASHTO Soil of Unit Weight and Density for Method Test Method Cone Sand the by in Place ASTM D 1557 T180)(AASHTO Compaction Laboratory for Method Test Effort Modified Soil Using of Characteristics ASTM D 1883 T193)(AASHTO Compacted Laboratory CBR of for Method Test Soils ASTM D 2167 T205)(AASHTO Soil of Unit Weight and Density for Method Test Method Balloon Rubber the by in Place ASTM D 2844 T190)(AASHTO and R-Value Resistance for Method Test Soils Compacted of Pressure Expansion ASTM D 2487 M145)(AASHTO Engineering for Soils Classification of Standard (Unified Soil Classification System) Purposes ASTM D 2922 T238)(AASHTO Soil and of Density for Method Test Methods Nuclear by in Place Soil-Aggregate ASTM D 2940 Material for Aggregate Graded Specification for ASTM D 3381 Asphalt Viscosity-Graded Specification for ASTM E 303 Frictional Surface Measuring for Method The layer of specified materials of layer The An index number derived from the from derived number An index The modulus of elasticity of roadbed elasticity of of modulus The Traffic consisting of automobiles or automobiles of consisting Traffic The ratio of the weight of water of weight the of ratio The A small projection on paver edges, formed edges, paver on A small projection The layer of brick pavers and setting bed, setting and brick pavers of layer The A measure of friction between the pavement the friction between of A measure The ability of a pavement to serve traffic that traffic serve to a pavement ability of The The top surface of existing soil or prepared soil upon soil or prepared existing of surface top The The layer or layers of specified materials of designed of specified materials of or layers layer The A measure of strength of a soil material. of strength of A measure Subgrade: Surface: Wearing Subbase: support a base. to on a subgrade placed thickness is constructed. system pavement which the layer. as a single modeled and surface, paving as the which serves of material being used in each layer of the pavement system. pavement the of layer in each used material being of through the use of suitable layer coefficients related to the type the to related coefficients layer suitable of use the through which may be converted to thickness of flexible pavement layers pavement flexible of thickness to which may be converted analysis of traffic, roadbed soil conditions, and environment and soil conditions, roadbed traffic, of analysis Structural Number (SN): Structural surface. and a tire assessing the risk of vehicles skidding on the pavement on the skidding vehicles risk of the assessing a tire and Skid Resistance: pavers to form the wearing surface. wearing the form to pavers in which the brick pavers are bedded, taken together with the together taken bedded, are brick pavers in which the Serviceability: Setting Bed (Bedding Course): cator of the probable resistance of brick to freezing and thawing. and freezing brick to of resistance probable the of cator observation. of time at the facility the uses Saturation Coefficient: Saturation An indi- water. in boiling immersion absorbed during weight the soil or other pavement material. pavement soil or other to water in cold immersion a masonry unit during absorbed by Resilient Modulus (MR): R-value: installation and in service. and installation Light Vehicular Traffic: Light Vehicular Lug (Spacer or Nib): during pavers the of chippage minimize to and sand jointing lighter vehicles. lighter for gap a positive provide to designed manufacturing, during Appendix C Guide Specification Section 02780

Flexible Brick Pavers 1.08 REFERENCES PART 1 - GENERAL A. ASTM C 33 - Concrete Aggregates 1.01 SECTION INCLUDES B. ASTM C 67 - Method of Sampling and Testing Brick and A. Brick Pavers Structural Clay Tile B. Sand Setting Bed C. ASTM C 144 - Aggregate for Masonry Mortar or D. ASTM C 1272 - Heavy Vehicular Paving Brick B. Bituminous Setting Bed PART 2 - PRODUCTS 1.02 RELATED SECTIONS 2.01 BRICK UNITS A. Section 02710 - Bound Base Courses A. Paving Brick: ASTM C 1272, Type F, Application PX [PS] B. Section 02340 - Soil Stabilization [PA], ______as manufactured by ______. C. Section 02720 - Base Courses Size ______x______x______. D. Section 02750 - Portland Cement Concrete Paving 2.02 SAND E. Section 02770 - Curbs A. Bedding Sand: ASTM C 33 1.03 QUALITY ASSURANCE *** BEDDING SAND CAN BE A. Brick Pavers: Test in accordance with ASTM C 67. USED AS JOINTING SAND. *** B. Mock-up B. Jointing Sand: ASTM C 144 1. Mock-up shall be 10 ft. by 10 ft. PART 3 - EXECUTION 2. When required, provide a separate mock-up for each 3.01 EXAMINATION type of brick and bonding pattern. A. Examine base for correct grade and elevations. 3. Do not start work until Architect/Engineer/Landscape B. Examine edge restraints for proper location. Architect has approved mock-up. 4. Use mock-up as standard of comparison for all work. 3.02 INSTALLATION OF FLEXIBLE PAVING C. Installer: Company with at least three years experience A. Spread bedding sand evenly over base and screed to in installing brick pavers. 1 in. thickness ± 3/16 in. The screeded sand should not be disturbed. 1.04 SUBMITTALS B. Lay pavers in the pattern(s) as indicated in the drawings. A. Submit samples of brick pavers to be used in Maintain straight lines. construction, showing range of colors, textures, finishes C. Joints between the pavers shall be approximately and dimensions. 1/16 to 1/8 in. wide. B. Submit sieve analysis for grading of bedding and D. Fill out area with cut pavers along edges or jointing sand. interruptions. C. Test reports for masonry units from a qualified testing E Vibrate the brick pavers into the sand using a plate laboratory. vibrator capable of 3000 to 5000 lbs. centrifugal force. 1.05 DELIVERY, STORAGE AND HANDLING The plate vibrator shall have a rubber mat or roller feet A. Store brick pavers off the ground to prevent to avoid chipping the pavers. contamination, staining or other defects. *** LUGS, CHAMFERS OR ROUNDED EDGED B. Cover sand with waterproof covering to prevent exposure PAVERS REDUCE CHIPPING ALONG THE to weather. Weigh down covering to prevent removal TOP EDGES OF THE PAVER. *** by wind. F. After the first pass of the plate vibrator, sweep jointing C. Store different types of aggregates separately. sand into the joints and vibrate again. Repeat the process until the joints are full. 1.06 ALLOWANCES G. Do not permit traffic on the pavers until the joints A. Refer to Section 01210 - Cash Allowances for the Cash are filled. Allowance Sum applicable to this section. H. Do not vibrate within six feet of unrestrained edges. B. This allowance includes purchase and delivery of brick I. Sweep excess sand off of pavement. pavers. Specially-shaped brick pavers shall have a separate allowance. 3.03 TOLERANCES A. The final surface elevation shall be flush with adjacent 1.07 PROJECT CONDITIONS construction. A. Do not install sand or pavers during rain or snowfall. B. Maximum variation in level shall be within ± 3/16 in. B. Do not install frozen materials. in 10 ft.

42 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide 43 NOTES NOTES

44 Flexible Vehicular Brick Paving: Heavy Duty Applications Guide Brick Industry Association 11490 Commerce Park Drive Reston, VA 20191 (703) 620-0010 (703) 620-3928 fax e-mail: [email protected] website: www.gobrick.com