Influence of Accelerating Admixtures on Strength Development of Concrete Under Wet and Dry Curing

Abstract

The effect of calcium chloride or a chloride-based strength accelerating admixture on the tensile and compressive strength development of concrete under both wet and dry curing was evaluated. Tension and compression tests were made at time intervals to 91 days. Tension tests included split-cylinder, modulus of rupture, and pullout. Both strength-accelerated concretes showed reduction in the split-cylinder tensile strength averaging 10 and 11 percent for wet and dry curing, respectively, at 91 days relative to the compressive strength, when compared to the tensile strength achieved for the non-accelerated control concrete. A single equation (given in text) for calculating tensile strength from the measured compressive strength is often given in concrete codes on the basis of tests on normal concretes. This can lead to everestimation of the tensile strength for strength-accelerated concrete, since tensile-strength acceleration may be much less than compressive-strength acceleration with calcium chloride or a chloride-based accelerator. This is further complicated with dry curing, since tensile strengths may drop significantly with time.