Cracking Tendency of Lightweight Concrete

By Benjamin E. Byard and Anton K. Schindler

Early-age cracking in bridge decks is a severe problem that may reduce functional life of the structure. In this project, the effect of using lightweight aggregate on the cracking tendency of bridge deck concrete was evaluated by cracking frame testing techniques. Cracking frames measure the development of stresses due to thermal and autogenous shrinkage effects from setting until the onset of cracking. Expanded shale, clay, and slate lightweight coarse and fine aggregates were used to produce internal curing, sand-lightweight, and all-lightweight concretes to compare their behavior relative to a normalweight concrete in a bridge deck application. Specimens were tested under isothermal curing conditions and match-cured conditions that simulate summer and fall placement scenarios.

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