Bridge Beams and Pier Caps with Self-Consolidating Concrete at Nimmo Parkway.

摘要

Self-consolidating concrete (SCC) has a very high level of work-ability as it easily fills form-work under the influence of its own mass without any additional consolidation energy. SCC can be placed in narrow and congested areas, fit the geometry of the element, and provide smooth surfaces. The purpose of this study was to investigate innovative, cost-effective, and aesthetically pleasing SCC mixtures for use in bridge beams and pier caps. The Virginia Department of Transportation used SCC in two bridges located south of Virginia Beach on the same project and in close proximity to each other. The bridges carry Nimmo Parkway traffic over Hunt Club Tributary and West Neck Creek. The bridge over West Neck Creek has 18 spans, and the bridge over Hunt Club Tributary has 2 spans. Precast SCC was used in the 220 beams on the two bridges, and cast-in-place SCC was used in three pier caps on one of the bridges. SCC mixtures were prepared at a prestressed concrete plant for the beams and a ready mixed concrete plant for cast-in-place applications. Cast-in-place SCC was delivered to the site by ready mixed concrete trucks. SCC for the bridge beams had high flow rates and attained high strength and low permeability. The surface of the beams had minimal blemishes. The cast-in-place SCC also had high strength and low permeability. In one of the four loads used in the first pier cap, marginal stability and lower but satisfactory strength were obtained. On the second and third day of the placements, SCC of uniform quality was obtained. Thus, compared to conventional mixtures, SCC is expected to have greater material-related costs because of changes in ingredients, particularly the addition of more and higher dosages of chemical admixtures. However, the ease of placement, speed of construction, and reduced labor requirements are expected to result in overall cost savings in structures with SCC. Further, the lack of problems with consolidation is expected to lead to improved surface appearance, strength, and durability; an increased service life; and lower life cycle costs. The study recommends that SCC be an option for precast and cast-in-place applications, and the Virginia Department of Transportation will include this option in its new 2016 Road and Bridge Specifications.