High-Early Strength Concrete for Closure-Pour between Bridge Girders

Accelerated bridge construction (ABC) technologies are being adopted by state departments of transportation. ABC increases the public’s and workers’ safety by lowering exposure to construction activities and also increases mobility and economic opportunities by reducing traffic interruptions and delays. As an alternative to ultra-high performance concrete (UHPC), Idaho Transportation Department (ITD) is interested in the suitability of high-early strength (HES) concrete Class 50AF with polypropylene fibers in closure pours between bridge deck bulb-T girders. The advantages of this alternate material are the reduction in costs and construction time. In the first phase of the project, an optimum concrete mix with good material properties was identified through a series of standard laboratory experiments and tests on larger specimens. In the second phase, field performance of a closure pour mix similar to the optimum mix found in Phase 1 is examined by placing the material in the closure pours between deck bulb-T girders in the SH-36 Bridge over Bear River near Preston, Idaho. Despite some deviations from the standard construction practices, the strain data in seven out of eight sets of gages (four sets of concrete and four sets of steel gages) shows low strains. The finite element computer model of the bridge shows that, if properly installed, the HES Class 50AF concrete with polypropylene fibers in the ITD’s 10-in. closure pours performs well under the AASHTO design truck loading.