Study on the Effectiveness of Shrinkage Reducing Admixtures on Plastic Shrinkage of Concrete

Concrete is plastic for a very short time from being cast to final setting time. But even in this early age, the concrete shrinks and induces cracking. Aiming to mitigate the impact of shrinkage in concrete, shrinkage reducing admixtures can be used in concrete. But the effect of shrinkage reducing admixture on the plastic period of concrete is not well defined, so there is a need for study in this area. This paper quantifies the effectiveness of shrinkage reducing admixture on cracking of plastic concrete. This is achieved by measuring the slump, compressive strength and plastic shrinkage cracks of concrete mixes. ASTM C1579 based mould is used to promote the plastic shrinkage crack in concrete. To assess the performance of shrinkage reducing admixture and to determine its optimum amount 0, 0.5, 1, 2, 3 and 4% dosage were analysed. The optimum percentage of shrinkage reducing admixture was found to be 2%.