Effect of Strain Gradient on the Stress-Strain Curve of Motar and Concrete


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Title: Effect of Strain Gradient on the Stress-Strain Curve of Motar and Concrete

Author(s): Llewellyn E. Clark, Kurt H. Gerstle, and Leonard G. Tulin

Publication: Journal Proceedings

Volume: 64

Issue: 9

Appears on pages(s): 580-586

Keywords: cracking (fracturing);microcracking;mortars (material);plain concrete;strains; stress-strain relationship

Date: 9/1/1967

Recent investigations have indicated that the microcracking of concrete and the associated stress-strain curve depend on the strain gradient. It is also recognized that the time rate of straining affects the stress-strain curve. The relative significance of these two effects, strain rate and strain gradient, has not previously been investigated. An experimental procedure was developed which provided for the individual control of bending and axial loads permitting maintenance of a constant strain gradient under uniform strain rates, making it possible to separate these two effects. Rectangular prisms of two different materials, mortar and concrete, were tested. The results indicate that the effect of a strain gradient on the stress-strain curves of mortar and concrete is minimal, except that the presence of a strain gradient tends to increase the maximum strain that can be reached before crushing occurs.