Shrinkage-Reducing Admixtures

The major concern with regard to the shrinkage of concrete is the potential for cracking, either in the plastic or hardened state, and any subsequent adverse impact on concrete durability or serviceability. In most construction situations, particularly pavement, bridge deck, and slab applications, the likelihood of plastic and drying shrinkage is often greater than that of other types of shrinkage, such as thermal contraction, autogenous shrinkage, and carbonation shrinkage. Fibers have been shown to minimize plastic shrinkage, and their use in concrete is increasing. In this article, basic information on the world's first shrinkage-reducing admixtures (SRAs), currently marketed under the tradename Tetraguard, are presented. Also presented is an overview of the mechanism and factors that affect drying shrinkage.