The effect of polycarboxylate admixtures on early-age autogenous shrinkage
Autogenous shrinkage tests were performed on cement paste mixtures containing varying dosages of different types of polycarboxylate-based high range water-reducing admixtures (HRWRA). The autogenous shrinkage testing was performed using corrugated tubes according to ASTM C1698 on three specimens at once and with measurements taken multiple times a minute. The repeatability of the ASTM C1698 test results in comparison with the results of previous work in literature was presented. In general, a correlation between increased dosage of polycarboxylate admixture and decreased autogenous shrinkage was noted. It was determined that, for 75% of cases, the largest dosage of admixture, resulted in the lowest amount of shrinkage. Additionally, autogenous shrinkage results for typical mixtures used in precast concrete applications (i.e., mixtures incorporating viscosity modifiers and fly ash) are presented.