Aesthetic Enhancement of Highway Bridges in Maryland Utilizing Precast Brick Veneer Facing Panels

Presents the decision making process leading up to the use of precast brick veneer facing panels, the design consid erations, the fabrication process and the final erection of facing panels on several highway bridges near Annapolis, Maryland.

he use of brick veneer facing project was the use of a precast brick panels has been a common prac veneer facing panel to face the bridge T tice in building construction for parapet and steel bridge girder (see many years. Only recently has Mary Figs. 1 and 2). John W. Narer, P.E. land expanded the use of this technol As the design consultant began Project Engineer ogy into their bridge construction work on this concept, he expressed Maryland State Highway Administration program. concerns regarding the use of individ Baltimore, Maryland Continued growth throughout the ual bricks and their method of anchor Baltimore-Annapolis corridor created age. Due to the traffic and the live the need for an expanded highway loads that would be placed on the system in the 1980s. A major compo bridge superstructure, the facing pan nent of this highway expansion was els would be subjected to continual the reconstruction of U.S. Route dynamic as well as vibratory loadings. 50/301 in the Annapolis area. Several It was important that each brick be an citizen groups voiced their concerns chored in a positive way to the cast-in regarding this construction and the im place portion of the facing panel. pacts that it could have on the historic After investigating several schemes, town of Annapolis. the design consultant recommended a The Maryland State Highway Ad scheme where the brick facing would ministration's Bridge Design Division be laid-up in the vertical position simi conducted an extensive study to estab lar to conventional brick veneer fac lish an architectural theme for the ing. Each brick had three core holes highway structures in this area. After with a minimum of one #3 bar passing Earle S. Freedman, P.E. much debate and community involve through the brick core holes. The #3 Deputy Chief Engineer ment, the decision was made to utilize bars were then anchored to the cast-in Office of Bridge Development Maryland State Highway a combination of brick and exposed place portion of the panel utilizi ng Administration aggregate concrete treatments. A par conventional triple-wire masonry rein Baltimore, Maryland ticularly innovative concept for this forcement between alternate courses

24 PCI JOURNAL - ORDINARY SURFACE 'i FACING PANEL JOINT AND FIN ISH (TYPICAL) 'i PARAPET CONTROL JOINT I r (TYPICAL) I I I I ~JOINT ttJOINT -1 LEVEL r-- - PLUMB JOINT (TYPICAL)

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1/2±=1/2" 1/4" 1/4" SLOPE TO FOLLOW ----.:-11='-:..._ __~---:-:---- l"OPEN JOINT BETWEEN GRADE I 1/2" OPEN JOINT PRECAST PANELS (TYPICAL) BETWEEN PRECAST ORDINARY SURFACE PANELS (TYPICAL) FINISH (TYPICAL)

PRECAST EXPOSED AGGREGATE CONCRETE TYPICAL ELEVATION

Fig. 1. Brick veneer precast concrete facing panel. of brick. All of the brick facing was designed to become an integral part of the facing panel by placing the laid-up SILICONE RUBBER JOINT SEALER brick into formwork and pouring the \ 1/2" EXPANSION JOINT precast concrete on top of the brick facing (see Figs. 3 and 4). \ 1/2" CORK TYPE EXPANSION JOINT MATERIAL Another area that the Maryland State Highway Administration's Bridge Design Office felt was critical CAST-IN-PLACE CONCRETE PARAPET ---._,_ in the design of the facing panel would (TYPICAL) be the ability to remove the panel. This removal feature was important for several reasons. First, in the event that a panel became damaged by an over-height vehicle, an individual panel could be removed for repairs or replacement. Second, the panels could be removed and stored during future 9 1/2" deck replacement operations. Finally, for maintenance reasons, if the panel became deteriorated and needed reha bilitation prior to the need for a deck replacement, the panel could be re moved for any necessary remedial BRICK FACED PRECAST CONCRETE PANEL repair work. (TYPICAL) Removability of the panels was ac complished by using a pair of mount ing brackets on each individual panel. Fig. 2. Precast panel mounting detail.

March-April 1992 25 Anchorage bolts for the panels were braces which supported the panel con In the spring of 1985, as the first placed from the underside of the tinuously along its bottom edge. This construction contract for U.S. Route bridge deck to facilitate their removal support feature was very desirable 50/301 rehabilitation was started, an (see Fig. 5). The panel was also sup since it provided additional structural alternate method of panel fabrication ported by a series of structural steel safety for the panels. was proposed by the fabricator. This method consisted of placing the bricks face down in a prepared formwork, vi brating high strength mortar into and PANEL CONCRETE CAST-IN-PLACE OVER between the bricks, then immediately PREFABRICATED BRICK FACING pouring the precast concrete over the brick facing without the aid of special bonding agents (see Fig. 6). This ap proach is similar to a method which #4 BAR AT 6" C/C was described by Walton in a recent • PCI JOURNAL paper.' Initially, this appeared to be a feasi ble alternative because it preserved the 3/ 16" DIA. integral characteristics of the brick and TRIPLE WIRE • MASONRY precast concrete, but some concerns REINFORCING AT were raised regarding the anchorage of ALTERNATE COURSES #3 BAR (AT LEAST ONE BAR the brick work. Upon investigating TO PASS THROUGH CORE several options, the fabricator pro OF EACH BRICK) posed the use of an H -shaped anchor which would be placed in the brick #4 BAR AT 6" C/C cores and extend back to the layer of #4 (PASS THROUGH reinforcing bars in the precast concrete. TRIPLE WIRE MASONRY A test panel was constructed prior to REINFORCING) beginning full-scale production to test PREFABRICATED the alternative method. After the test BRICK VENEER FACING panel had cured, it was cut diagonally to expose a cross section of the brick #4 BAR AT 6" C!C facing, reinforcement and precast con crete (see Fig. 7). The results proved Fig. 3. Typical section of proposed facing panel. that the bricks were integral with the precast concrete and that the alter native method of fabrication was acceptable. PANEL CONCRETE CAST-IN-PLACE Several factors had to be considered OVER PREFABRICATED in the full-scale production of the fac BRICK FACING ing panels. First, as a result of the #4 VERTICAL BARS AT 6" C/C TEE SHAPED RUBBER JOINT SEAL (HORIZONTAL BARS AT REAR FACE OF PANEL bridges being located on geometric NOT SHOWN) vertical curves, each individual panel 3/ 16" DIA TIE AT ALTERNATE COURSES AT ENDS OF PANEL is a different shape. The panels are actually a series of rhombuses which required adjustments to the formwork prior to fabricating each panel. Sec ond, the arch configuration required a number of the bricks to be cut to pre cise shapes. Third, the center portion of the arch configuration has an ex posed aggregate finish. This resulted in the use of a concrete retarder to 3/ 16" DIA. TRIPLE WIRE allow the aggregate to be exposed PREFABRICATED MASONRY REINFORCING after placing the concrete. BR ICK FACING Finally, quality control was of the #3 BAR (AT LEAST ONE BAR TO PASS THROUGH CORE utmost importance. Each year, mil OF EACH BRICK) lions of people will view these struc tures as they are traveling along the Fig. 4. Plan view section of proposed facing panel. highway. By precasting the individual

26 PCI JOURNAL panels at a production facility, we PRECAST were able to accomplish our quality ATIACHMENT ANGLE '- FACING control objectives as well as provide a PANEL SLOTTED HOLES TO ', product which is superior in its fin ALLOW FOR ADJUSTMENTS ""' "- ished appearance. ~ '\ The production facility was a small ~ \ '\_ scale operation that employed three \\ '\_ production workers. The facility had MOUNTING BRACKET ~ the capability to produce two panels at a time, with typical panel fabrication NUT AND WASHER ~ TACK WELDED ~ ' taking approximately five days. TO BRACKET The first day involved preparation of the formwork and the layout of the BRIDGE DECK ----- actual brick pattern. The second day, 'I each individual brick was cut and laid into its precise location with the rein forcing steel being placed as required. On the third day, the high strength mortar mix was vibrated between the bricks and the precast concrete was poured over this prepared facing. The remainder of the fabrication time was related to curing, stripping of form work and final finishing on the brick panel. Panels were shipped, in units of four each, to the bridge location and placed on the bridge deck adjacent to 3/4' DIA BOLT GALVANIZED STEEL PLATE their final location. Because more than 60,000 vehicles Fig . 5. Mounting bracket detail. use U.S. Route 50/301 , maintenance of traffic dictated that the roadway re main open during the daytime hours. PRECAST PANEL CONCRETE PLACED OVER PREFABRICATED Each night, the roadway was closed BRICK FACING down to one lane and several panels #4 BAR AT 6' C/C were erected. Without the use of pre cast concrete panels, this operation would not have been feasible. The need for intricate scaffold supports and protective shields over the road way were eliminated, and final erection of the panels was easily accomplished. #4 BAR AT 6' C/C \ Vandalism was another concern which was given consideration during \ the design evaluation. The contract H-SHAPED REMOVE RUBBER RODS included provisions for the use of an WIRE ANCHOR - AND POINT UP JOINTS anti-graffiti treatment on the precast 2 PER BRICK AFTER FORM REMOVAL facing panels and the laid-in-place (TIE WIRE ANCHORS TO #4 REINFORCING) brick facing on the bridge abutments PREFABRICATED and piers. After experimenting with BRICK FACING the anti-graffiti coating on several panels, it was apparent that the slight discoloration caused by the coating resulted in an undesirable appearance. DRY SAND TO ALLOW RUBBER ROD REMOVAL Subsequently, the use of this type of product was eliminated from the con HIGH STRENGTH MORTAR RUBBER ROD tract requirements. VIBRATED INTO JOINTS TO FORM JOINTS Three of the proposed bridge struc AND BRICK CORES JOINT FORMING tures have been completed (see Fig. 9), AS SHOWN one is under construction and two are Fig . 6. Typical section of facing panel proposed by contractor.

March-April 1992 27 in the future, precast concrete will continue to play an active role in the aesthetic enhancement of bridge struc tures with pleasing results.

Technical Specifications • Brick: "Iron Blue MMC" manufactured by the Glen-Gery Corporation, Balti more, Maryland, in conformance with ASTM C-216, Grade SW, Type FBS Cored Brick. • High strength mortar: Sand/cement mortar mixed on a 2 to 1 ratio with a 6 to 8 in. (152 to 203 mm) slump. Mortar was in confor mance with ASTM C270 Type S. • Exposed aggregate: Washed gravel conforming to the class A requirements of AASHTO Fig. 7. Exposed cross section of precast test panel. M-80 and meeting the grading re quirements of AASHTO M-43, Size in the bidding stage. We believe that an honorable mention award from the No.6. the use of precast brick veneer facing Consultant Engineers Council as one • Precast concrete: panels has allowed us to meet our aes of the outstanding civil engineering Maryland State Highway Adminis thetic objectives as well as our design projects in Maryland (see Fig. 8). In tration portland concrete Mix No. 6 objectives. The resulting bridge struc December 1991, the entire highway [4500 psi (31 MPa)] with a 2 to 5 in. tures have received much public praise construction project received the (51 to 127 mm) slump. and also professional recognition. Masonry Institute's Shield of Masonry • Cost per unit surface area of panel In July 1988, the bridge carrying for the innovative and non-traditional in-place: 2 U.S. Route 50/301 over I-97 received use of brick masonry. We believe that, $39 per sq ft ($420/m ).

Fig. 8. Bridge carrying U.S. Route 50/301 over 1-97 eastbound.

28 PCI JOURNAL Fig. 9. Completed brick facing panels at bridge site.

Credits - Donald W. Fiske, project engineer, REFERENCE WBCM Owner: Maryland Department of I. Walton, A. E., "Production of Brick Ve Transportation, State Highway Ad - E. Bruce Weisner, project engineer, neer Precast Concrete Panels," PCI ministration, Baltimore, Maryland KCI JOURNAL, V. 31, No. 3, May-June 1986, pp. 48-63. -John W. Narer, design project General Contractor and Precast Con manager crete Erector: The Driggs Corpora -Randell Wiley, construction pro tion, Capitol Heights, Maryland ject engineer -Frank Middleton, bridge super- -William O'Neill, construction intendent project engineer Precast Concrete Manufacturer: M/G Architectural Products, Inc., Mil Architect/Engineer: Whitney, Bailey, ford, Virginia Cox and Magnani/Kidde Consul tants, Inc., Joint Venture, Baltimore, Owners: Charles and John Meyer, Maryland Baltimore, Maryland

March-April 1992 29