“Moving Advancements into Practice” MAP Brief September 2019 Best practices and promising technologies that can be used now to enhance paving

Overview of the Guide for Concrete Pavement Distress Assessments and Solutions

www.cproadmap.org Introduction who are responsible for managing concrete September 2019 pavement assets. Managing these assets MAP TRACK 6 The Guide for Concrete Pavement Distress includes monitoring pavement performance, Assessments and Solutions, published in developing project concepts, developing and PROJECT TITLE October 2018, is intended to assist with pave- administering pavement repair projects, and Overview of the Guide for ment preservation by helping to identify the overseeing system maintenance. Users of this Concrete Pavement Distress Assessments and Solutions causes and remedies for concrete pavement guide may include the following: distress. By understanding the basic principles • Pavement inspectors and design engineers AUTHORS of concrete pavement preservation, engineers Michael Ayers, Tom Cackler, will be able manage their pavement networks • Field engineers responsible for developing Gary Fick, Dale Harrington, Doug to provide safe and dependable roadways project concepts Schwartz, Kurt Smith, Mark B. while minimizing disruptions to the public for • Construction and maintenance staff Snyder, and Tom VanDam repair and maintenance activities. responsible for administering contracts for repair of concrete pavement Establishing a proactive approach to pavement EDITOR • Asset management and pavement manage- Sabrina Shields-Cook condition monitoring and planned mainte- ment engineers nance activities will reward owner agencies • Consulting engineers SPONSORS with not only long life from their concrete Federal Administration pavements but also reduced ownership costs National Concrete Consortium and minimal disruption to the traveling National Concrete Pavement Why this Guide Was public. Technology Center Developed The number of failure mechanisms that may MORE INFORMATION occur in concrete are fairly limited. However, Pavements and their underlying support Dale Harrington most distress is a combination of more than layers are a complex, interdependent system. HCE Services, Inc. The performance of this system is influenced [email protected] one mechanism, exhibiting in an array of dif- ferent forms. This manual goes into the details significantly by loading, climatic of the different types of distress observed in conditions, maintenance practices, the origi-

The Long-Term Plan for Concrete the field. Pavement Research and Technology (CP Road Map) is a It is also important to remember that the pres- national research plan developed and jointly implemented by the ence of one or more distress type in a concrete concrete pavement stakeholder pavement may not trigger corrective action by community. Publications and other support services are the engineer because such distress types may provided by the Operations have limited impact on the pavement’s overall Support Group and funded by the Federal Highway Administration. functionality. Moving Advancements into Practice (MAP) Briefs describe The authors and contributors to this manual innovative research and have shared their wealth of knowledge and promising technologies that can be used now to enhance experience to help agencies achieve the goal concrete paving practices. The of minimizing the cost of ownership of their September 2019 MAP Brief provides information relevant concrete pavements. to Track 6 of the CP Road Map: Concrete Pavement Construction, Reconstruction, and Overlays. Who this Guide Is for This MAP Brief is available at www.cproadmap. org/publications/ This guide was developed for transportation MAPbriefSeptember2019.pdf. agency personnel and consulting engineers CP Road MAP Brief September 2019

nal design, and the construction of the pavement structure, • Kevin McMullen, Wisconsin Concrete Pavement foundation layers, and drainage system. Over the life of a Association concrete pavement, distresses can occur—and, in most cases, • Brad Mirth, Oklahoma DOT the distresses can be attributed to multiple causes. • Andy Naranjo, Texas DOT Accurately identifying the distress, understanding the cause(s) • Jim Pappas, Delaware DOT of the distress and how to prevent it on future projects, and • Randy Riley, Illinois Chapter, Inc. – American Concrete determining the proper repair procedures can be complicated. Pavement Association The purpose of this guide is to clearly address these elements • Gordon Smith, Iowa Concrete Paving Association/ in a user-friendly, uncomplicated, and comprehensive manner. National CP Tech Center The need to cost-effectively manage pavement assets has • Jeff Uhlmeyer, Washington State DOT become increasing more difficult and important. This is due to • Tom Yu, FHWA several factors. First, agency budgets are being stretched. Sec- • Matt Zeller, Concrete Paving Association of Minnesota ond, experienced staff is waning. Third, the public’s demand to minimize disruptions while providing a safe riding surface Authors is increasing. • Michael Ayers, Global Pavement Consultants, Inc. – Selecting a pavement preservation strategy that does not ad- Chapters 3, 12, 13, and 19 dress the root cause of a distress can result in wasted resources • Tom Cackler, Woodland Consulting, Inc. – Chapters 1 and additional inconvenience to the public. and 14 Historically, distresses in concrete pavements have been identi- • Gary Fick, Trinity Construction Management Services, fied largely through visual surveys with limited investigation Inc. – Chapters 17 and 18 into the underlying cause(s) of the distress, and often with • Dale Harrington, HCE Services – Chapters 8, 12, and 19 limited knowledge of how to cost-effectively maintain a con- • Doug Schwartz, Gateway Engineering and Training LLC crete pavement in good condition. However, in the last few – Chapter 9 years, not only have significant technical advancements been • Kurt Smith, Applied Pavement Technology, Inc. – Chap- made in distress assessment tools but more robust preservation ters 2, 4, and 5 treatment options have also been developed. • Mark B. Snyder, Pavement Engineering and Research Consultants – Chapters 6, 7, 15, and 16 This guide incorporates proven and cost-effective solutions into a framework that assists you in matching the appropriate • Tom Van Dam, Nichols Consulting Engineers, Chtd. – solution(s) to a given distress. Chapters 10 and 11

How this guide was developed How to use this guide The National Concrete Pavement Technology (CP Tech) This guide is intended to be used in combination with the Center brought together leading national experts on concrete Federal Highway Administration’s (FHWA’s) Distress Identi- pavements in the engineering community to develop the tech- fication Manual for the Long-Term Pavement Performance nical content of this guide. In addition, a technical advisory Program (Miller and Bellinger 2014 ) in answering the fol- committee with experience from Departments of Transpor- lowing questions: tation (DOTs) and industry provided critical reviews and insights throughout development of this guide. The authors • Which distress is present? themselves have drawn upon their rich practical experience • What caused it? and lessons learned to make this a state-of-the-art resource for • How can it be prevented? the management of concrete pavements. • Which repair options are available? Technical Advisory Committee The chapters in this guide provide a detailed discussion of • Andy Bennett, Michigan DOT specific distresses that may need to be addressed. Each of the • Chris Brakke, Iowa DOT chapters is typically formatted as follows: • Tom Burnham, Minnesota DOT Chapter Number. Title of Distress • Dan DeGraaf, Michigan Concrete Association • John Donahue, Missouri DOT 1. Description • Brian Killingsworth, National Ready Mixed Concrete ––Written summary of distresses 2 Association ––Images (with short description) of distresses CP Road MAP Brief September 2019

2. Severity look like. ––Opening dialogue When determining the best options for repairing a particular ––Table X. Summary of Severity of Distress distress, it is important to have a general understanding of 3. Testing the characteristics of common full-depth concrete pavement ––Field tests types. Jointed plain concrete pavement (JPCP) and continu- ––Laboratory tests ously reinforced concrete pavement (CRCP) each have their own design and performance characteristics. A brief explana- 4. Identification of Causes tion of each is provided. ––Opening dialogue ––Table X. Physical and Material/Chemical Causes of Chapter 2 - Surface Defects Distress Minor deformities or imperfections that are limited to the 5. Evaluation surface of a concrete pavement ––Distress subject(s) are often referred to as surface º Cause defects. These defects can include º Prevention map cracking (also called crazing), plastic shrinkage cracking, scaling, ––Table X. Summary of Causes and Prevention of surface polishing, surface wear, Subject Distress and popouts/mortar flaking. These 6. Treatment and Repairs distresses typically do not signifi- ––Repair type(s) for specific repair and selection cantly detract from the structural integrity of the pavement, ––Maintaining pavement subject but can have an impact on its functional performance and its 7. References aesthetic appeal. Chapter 3 - Surface Delamination

Organization and Scope of this Guide Surface delamination (subsequently referred to as delamina- This guide is organized into three divisions and addresses the tion) in concrete pavements is following pavement types: closely related in appearance to scaling and spalling. However, the Division 1: Full-Depth Concrete Pavements mechanism of failure is different, as is discussed in detail in this • Jointed Plain Concrete Pavement (JPCP) chapter. • Continuously Reinforced Concrete Pavement (CRCP) Delamination may be viewed as Division 2: Concrete Overlays the development of a horizontal crack within the slab that results in separation of the sur- • Bonded Concrete Overlay on Asphalt (BCOA) face layer to a depth of 0.5 to 2 in. (12.5–50 mm) from • Bonded Concrete Overlay on Concrete (BCOC) the remaining concrete. Delamination may be limited or • Unbonded Concrete Overlay on Asphalt (UBCOA) widespread depending on the basic cause of the separation. • Unbonded Concrete Overlay on Concrete (UBCOC) Although delamination is normally seen adjacent to pave- ment joints and may extend 3 ft (1 m) or more into the slab, Division 3: Laboratory and Field Testing it can also occur anywhere in the slab. All previously listed pavement types. Scaling, as discussed in Chapter 2 of this manual, has a simi- lar appearance to delamination, but does not extend beyond approximately 0.5 in. (12.5 mm) in depth. Compression Division 1: Full-Depth Concrete spalling at joints or transverse cracks, discussed in Chapter 8, Pavements Chapters and Distresses may also appear similar but is due to the intrusion of incom- pressible materials. Chapter 1- Introduction De-bonding of a bonded concrete on concrete overlay or This chapter helps to identify where more detailed guidance separation of the lifts in two-lift paving is discussed in Chap- on full-depth pavement distress can be found within Divi- ters 15 and 16 and is not considered in this discussion of sion 1 of this manual. A brief overview of each chapter is delamination. provided along with a photo of what this type of distress may 3 CP Road MAP Brief September 2019

Chapter 4 - Material Related Cracks Chapter 7 - Corner Cracking

Materials-related distresses (MRD) Corner cracking (also known as a are failures that occur in concrete “corner break”) is a distinct full- pavements as the result of the depth fracture in a jointed concrete properties of the materials in the pavement. Corner cracks intersect pavement and their interaction with adjacent transverse and longitudi- the environment (Van Dam et al. nal joints at an angle of approxi- 2002). MRDs in concrete pave- mately 45 degrees with the direc- ments are commonly typified by a tion of traffic. The lengths of the network of multiple, closely spaced cracks, often accentuated sides are rarely less than 1 ft (0.3 m) and are always less than with staining or deposits. However, visual inspection alone one-half the width of the slab (by definition) on each side of cannot confirm the presence or absence of material-related the corner. Cracks with longer legs are considered diagonal issues. Laboratory testing of pavement core samples is required cracks (see Chapter 5). to definitively confirm the mechanisms that may be contribut- ing to distress. Chapter 8 Spalling Chapter 5 - Transverse /Diagonal Cracking Transverse and longitudinal joint/ crack spalling in concrete pave- Cracking refers to a distinct fracture ments is one of the most common, in a jointed concrete pavement. if not the most predominant, Transverse cracking, also called mid- concrete pavement distress. Joint panel or mid-slab cracking, is ori- spalling is joint deterioration, ented laterally across the pavement which refers to cracking, chipping, and perpendicular to the pavement or fraying of the concrete slab joint centerline; whereas diagonal crack- or crack edges of the transverse and longitudinal joints. The ing is oriented obliquely across a slab, at roughly a 30–60 spalling may develop predominantly in the top few inches of degree angle from the pavement centerline. Slab cracking may the slab, or may develop at a greater depth below the sur- also develop longitudinally, in which the crack is oriented face, depending on the environmental conditions, eventually parallel to the pavement centerline. This chapter focuses on reaching full pavement depth. Spalling problems include loose transverse and diagonal cracking, with Chapter 6 providing debris on the pavement, shallow vertical drops and roughness. detailed information on longitudinal cracking. According to FHWA, spalling is any cracking, breaking, chip- ping, or fraying of the slab edge within 12 in. from the face of Regardless of orientation, these types of cracks are differentiat- the transverse or longitudinal joint. It can be expanded both ed from map cracking or other surficial cracking (see Chapter in width and depth through continuous deterioration. 2) in that they are distinct cracks that typically extend through the entire thickness of the slab. Moreover, these cracks can also Chapter 9 - Faulting develop in conjunction with one another to produce what is often referred to as a shattered or broken slab (in which the Faulting is the difference in el- slab is divided into three or more pieces). Although cracking evation across a joint or crack in is perhaps the most common structural distress in concrete a pavement due to loss of load pavements, not all cracks are necessarily indicative of structural transfer and is a symptom of loss failures. of uniform subgrade support. The loss of uniform support is due to Chapter 6 - Longitudinal Cracking pumping, which is the expulsion of soil and water due to traffic A clear rupture through the full through a pavement joint, crack, or pavement/ edge depth of a jointed concrete pave- resulting in lack of load transfer. ment is referred to as a crack. Lon- gitudinal cracking is nearly parallel Chapter 10 - Joint Warping and Curling to the pavement centerline or - shoulder joint. Longitudinal cracks Concrete slabs placed on grade undergo non-uniform volu- vary from map or surface cracks metric changes due to temperature and moisture gradients. because they extend through the With regards to the temperature gradient, this changes entire depth of the pavement. Other types of cracking include throughout the day. The slab is normally colder on the top transverse, diagonal, and slab cracking. This chapter will focus than the bottom from late at night through mid-morning, re- 4 on longitudinal cracking. sulting in a negative temperature gradient. Under these condi- CP Road MAP Brief September 2019 tions, the slab will have a tendency continuous longitudinal reinforce- to undergo upward curling due to ment ranging from approximately the lower surface temperature. As 0.70 to 0.80 percent of the cross- the top of the slab warms in the sectional area of the pavement course of the day, its temperature slab. Transverse reinforcement is will become greater than that at also typically used but consists of the bottom developing a positive individual bars placed at approxi- temperature gradient, resulting in mately 3 ft (0.9 m) spacing. a tendency to develop downward curvature as the concrete at the surface expands. Division 2: Concrete Overlay Chapters Chapter 11 - Blowups and Distresses A blowup is a result of localized Chapter 14- Introduction upward movement or shattering of a slab along a transverse joint or Division 2 addresses the family of bonded and unbonded crack (Miller and Bellinger 2014). concrete overlays and distresses that are unique to each overlay Blowups often occur after heavy type. When determining the best options for repairing a rainfall occurs followed by high particular distress, it is important to have a general under- temperatures resulting in high standing of the characteristics of the different types of concrete expansion buildup of pressure that overlays. Although some distresses in concrete overlays are can be dramatically released as the pavement thrusts upwards the same as full-depth concrete pavement, there are unique and/or shatters. Contributing factors are incompressible in differences. Concrete overlays are placed over existing asphaltic the joint, high coefficient of thermal expansion (CTE) of and concrete pavements that have some degree of distress in coarse aggregate as the concrete temperature increases, and them. How the distresses in the underlying pavement are ad- long transverse joint spacing. dressed varies for the different overlay types. When addressing distresses that develop in the overlay itself, it is important to Chapter 12 - Subgrades and Bases understand basic design approaches for each type of overlay. Other than vehicle loading, the Chapter 15 – Bonded Concrete Over Asphalt & principal cause of distress in con- Composite (BCOA) crete pavements is volume change, or, put another way, movement (i.e., either in the concrete itself or in the underlying support sys- tem). The volume changes result in movements in the concrete that either exceed the design parameters of the pavement when distresses occur or when not anticipated in the design. The volume change in concrete itself has been covered in other Distress mechanisms that are specific to BCOA, include chapters of this manual. This chapter is devoted to the dis- the following: loss of (or failure to develop) adequate bond tresses in the concrete pavement due to volume changes in strength between the concrete overlay and the underlying the subgrades and bases. asphalt, non-uniform support of the concrete overlay panels, and improper sawing of the joints (locations and/or depth). The distresses from volume change (movement) in concrete Each of these mechanisms may, in turn, have more than one pavement from the subgrade and base typically show up as potential cause (e.g., non-uniform support may result from cracking as the result of settlements or heaves of the sub- poor or inadequate pre-overlay repairs, asphalt layer strip- grade/base. Therefore, this chapter has been developed and ping, or other issues). formulated around settlement and heave categories since they do represent the majority of subgrade and base distresses. The resulting BCOA distresses are generally described in conventional terms (i.e., corner breaks or corner cracking, Chapter 13 - CRCP transverse and longitudinal cracking, reflection cracking, Continuously reinforced concrete pavements (CRCP) are wide joints, transverse joint faulting, and joint spalling), generally used for heavily trafficked roadway applications. but their causes can often be traced to somewhat different These pavements differ from the more widely used jointed mechanisms than for conventional pavement distresses with plain concrete pavements (JPCP) due to the presence of the same names. 5 CP Road MAP Brief September 2019

Chapter 16 – Bonded Concrete Over Concrete (BCOC) ment thickness. Thus, UBCOC Bonded concrete overlays are thicknesses are only relatively thin (typically 2–6 slightly thinner in. [50–150mm]) concrete than what would layers that are bonded to a be required by traffic estimates for a full-depth concrete pave- pre-existing concrete pave- ment placed on a granular subbase. These concrete pavements ment surface to create a paving layer that acts monolithically. can be designed as jointed plain concrete pavement (JPCP), The development and maintenance of the bond between with or without load transfer. the two layers is directly considered in the overlay thickness design and is, therefore, essential to the performance of the Each of the distresses covered in Chapters 2 through 15 should system. be consulted for additional information on the identification, causes, evaluation and treatment of the observed distresses Bonded concrete overlays are also susceptible to a few found in UBCOCs. However, there are some of these distress- unique distress mechanisms. For BCOC pavement, these es which may manifest themselves differently in UBCOCs. So, mechanisms are generally related to improper sawing of the for a given distress observed in a UBCOC, the cause(s) may joints (locations and/or depth), loss of (or failure to develop) be as described in the appropriate distress chapter for a non- adequate bond strength, inadequate repair of the underlying UBCOC pavement; or the cause may be related to the design pavement prior to overlay, and use of the bonded overlay on and construction of the UBCOC. a poor candidate project. The resulting distresses may initially appear to be conventional cracks or spalls, but their causes Chapter 19 – Field Evaluation and Laboratory Testing can be traced to different mechanisms than that of conven- Procedures tional pavement cracking and spalling. Field and laboratory testing is an important component in Chapter 17 – Unbonded Concrete Over Asphalt & determining the cause of observed distresses. Field evaluation Composite (UBCOA) and laboratory testing is summarized in each chapter that pertains to a specific pavement distress. Each chapter then refers the reader to this chapter for a comprehensive analysis of a particular test or procedure.

Field Evaluation Testing Procedures

This section describes 14 The design of UBCOA treats the existing pavement as a stiff different testing procedures subbase and not part of the overlay thickness. UBCOA thick- for field evaluation. The nesses have traditionally been somewhat thinner than what procedures described are not would be required by traffic estimates for a full-depth con- all-inclusive but represent crete pavement placed on a granular subbase. Typical thick- some of the most common ness ranges from 4 in. to 11 in. These concrete pavements field-testing procedures. can be designed as jointed plain concrete pavement (JPCP), Laboratory Testing Procedures with or without load transfer or continuously reinforced con- crete pavement (CRCP). Joint spacing for JPCP unbonded The tests shown in this chapter overlays should be a function of the design thickness. are differentiated by concrete material tests and those used Each of the distresses covered in Chapters 2 through 13 can to characterize the base and be observed in unbonded overlays. However, some of these subgrade materials. This list is distresses may manifest themselves differently in UBCOAs. not all-inclusive; note that new So, for a given distress observed in a UBCOA, the cause(s) test methods and equipment may be as described in the appropriate distress chapter for a may be available to address a non-UBCOA pavement; or the cause may be related to the specific testing need. design and construction of the UBCOA. The descriptions of each test listed are brief and the actual test- Chapter 18 – Unbonded Concrete Over Concrete ing guide should be referenced and followed when administer- (UBCOC) ing the testing procedure. The design of UBCOCs treats the existing pavement and 6 separation layer as a stiff base, and not as a part of the pave- CP Road MAP Brief September 2019

Where to Find Additional Information Reference Information for this MAP Additional information on concrete pavement distresses can be Brief found at the resources listed below. • Harrington, D., M. Ayers, T. Cackler, G. Fick, D. Schwartz, K. Smith, M. B. Snyder, and T. Van Dam. • Guide for Concrete Pavement Distress Assessments and 2018. Guide for Concrete Pavement Distress Assess- Solutions ments and Solutions: Identification, Causes, Prevention, https://intrans.iastate.edu/app/uploads/2019/01/concrete_ and Repair. National Concrete Pavement Technology pvmt_distress_assessments_and_solutions_guide_w_cvr.pdf Center, Iowa State University, Ames, IA. https://intrans. • Concrete Pavement Preservation Guide iastate.edu/app/uploads/2019/01/concrete_pvmt_dis- http://www.cptechcenter.org/technical-library/documents/ tress_assessments_and_solutions_guide_w_cvr.pdf preservation_guide_2nd_ed_508_final.pdf • Miller, J. S. and W. Y. Bellinger. 2014. Distress Iden- • Distress Identification Manual for the Long-Term Pavement tification Manual for the Long-Term Pavement Per- Performance Program formance Program. Fifth Revised Edition. FHWA- https://www.fhwa.dot.gov/publications/research/infrastruc- HRT-13-092. Federal Highway Administration, Office ture/pavements/ltpp/13092/13092.pdf of Infrastructure Research and Development, McLean, • Guide for Partial-Depth Repair of Concrete Pavements VA. https://www.fhwa.dot.gov/publications/research/ http://www.cptechcenter.org/technical-library/documents/ infrastructure/pavements/ltpp/13092/13092.pdf PDR_guide_Apr2012.pdf • Van Dam, T. J., L. L. Sutter, K. D. Smith, M. J. Wade, • Guide to the Prevention and Restoration of Early Joint Dete- and K.W. Peterson 2002. Guidelines for Detection, rioration in Concrete Pavements Analysis, and Treatment of Materials-Related Distress in http://www.intrans.iastate.edu/research/documents/research- Concrete Pavements, Volume 1: Final Report, FHWA reports/2016_joint_deterioration_in_pvmts_guide.pdf Publication FHWA-RD-01-163. https://www.fhwa.dot. gov/publications/research/infrastructure/pavements/ • Integrated Materials and Construction Practices for Concrete pccp/01163/ Pavements: A State-of-the-Practice Manual https://intrans.iastate.edu/app/uploads/2019/05/IMCP_ manual.pdf

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