Reducing concrete shrinkage by aggregate treatment with polymer latex and water repellent

Abstract

While the drying shrinkage of concrete is due mainly to the shrinkage of cement paste, the shrinkage of rock aggregate also plays a significant role. Hence, it should be possible to reduce the shrinkage of concrete by hampering the moisture movement across the rock aggregate so that the aggregate would not shrink after casting. Since rock is porous in nature, the moisture movement across rock can only be hampered by blocking or sealing the pores. For this purpose, the use of polymer latex or water repellent to treat the aggregate before casting is proposed. To investigate the effectiveness of such aggregate treatment, a testing program was launched, in which the water absorptions of untreated and treated aggregates were tested and the shrinkage strains of concrete made with the untreated and treated aggregates were measured up to over 600 days. The results demonstrated that the proposed aggregate treatment with polymer latex or water repellent can significantly reduce the concrete shrinkage.