Title: Effect of Straining Rate on the Compressive Strength and Elastic Properties of Concrete
Author(s): D. Watstein
Publication: Journal Proceedings
Appears on pages(s): 729-744
Keywords: no keywords
The effect of the rate of application of load was investigated using bonded wire strain gages in compressive tests of two concretes having approximate compressive strengths of 2500 and 6500 psi. The concrete was tested in the form of 3 x 6-in. cylinders at rates of straining ranging from 10-^6 to about 10 in. per in. per set, with the corresponding durations of test ranging from 30 min. to 0.0003 sec. The higher rates of straining were obtained by loading the concrete specimens in a drop-hammer machine. The rate of loading in the drop-hammer machine was controlled by placing rubber buffers of appropriate thickness and hardness on top of the concrete specimens. The compressive strength of the concrete increased with the rate of loading. The maximum ratio of dynamic to static compressive strengths was about 1.8 for a rate of straining of 10 in. per in. per sec. The values of the secant moduli of elasticity increased significantly with the rate of application of load; the maximum ratio of dynamic to static modulus was 1.47 for the "weak" concrete and 1.33 for the "strong" concrete. Resistance of the con-crete to impact as measured by its ability to absorb strain energy also in-creased with the rate of application of load.