Fracture Energy and Tension Properties of High-Strength Concrete

Abstract

A test setup and adequate instrumentation were developed to record the tension properties of high-strength concrete, including the postpeak softening response. The direct uniaxial tension tests were performed under a strain-controlled mode through a close-loop testing machine. The splitting tensile strength and modulus of rupture were also recorded conforming to standard ASTM test procedures. Test results revealed that high-strength concrete exhibits a more brittle and stiffer behavior with a large initial modulus of elasticity and a more sharply descending branch of the stress-deformation curve beyond the peak load. The unique softening behavior and the more brittle nature of high-strength concrete were expressed in terms of a stress-displacement (crack width) diagram and fracture energy. The fracture energy of high-strength concrete is estimated to be about five times the area under the ascending portion of the stress-deformation curve, compared to a corresponding value of 10 estimated for normal-strength concrete. Based on the test results, a constitutive relationship is recommended for the behavior of high-strength concrete in tension, including postpeak softening response.