Water-Reduction and Strength Gain of Concrete Affected by Water-Reducing Admixtures

Abstract

To examine the effectiveness of water-reducing agents, typical one air-entraining agent, eight water-reducing admixtures and ten brands of normal portland cement now widely distributed throughout our country have been selected and used with some combinations.
Comparative tests have been performed of fresh concrete with respect to its water-reduction, bleeding and initial hardening, and of hardened concrete with respect to its strength gain, all these with the above-mentioned admixture, and, for contrast, of the control concrete having the same cement content of 300kg/m³ and consistency of 7.5cm without the critical admixture.
The results of the tests show that the good quality of water-reducing admixtures can reduce water requirement by 10 to 15 percent, bleeding per unit area by more than 30 percent and give higher compressive strength without any harmful effect on setting.