Influence of superplasticizer and shrinkage-reducing admixtures on early age shrinkage of concrete

The influence of superplasticizer (SP) and shrinkage-reducing admixtures (SRA) on the early age shrinkage of concrete with a controlled slump of 8010 mm was investigated using a measuring apparatus developed specially. In addition, the influence of early age curing methods on the early age shrinkage of concrete was also studied. The early age shrinkage was increased sharply by the addition of SP when the concrete was exposed to the drying environment after initial setting. While under the same conditions the addition of SRA could reduce the early age shrinkage effectively. However, under sealed curing conditions at the early age, concretes with or without chemical admixtures all exhibited low early age shrinkage, which implies if a good method for curing could available then the addition of SRA will be unnecessary and the adverse effect of SP in enlarging shrinkage could also be eliminated.