Coupled strain rate and temperature effects on the tensile behavior of strain-hardening cement-based composites (SHCC) with PVA fibers

Abstract

This paper reports the experimental findings on the tensile behavior of Strain-hardening cement-based composites (SHCC) subjected to elevated temperatures and different strain rates and to combinations of these parameters. Uniaxial tension tests with in-situ temperature control were performed at 22°C, 60°C, 100°C and 150°C. In addition, the effect of loading rate was investigated using the strain rates of 10−5s−1, 3×10−4s−1 and 10−2s−1 at all four temperatures considered. It was shown that tensile strength decreases both with an increase in temperature and with a decrease in the strain rate. The strain capacity increases with decreasing strain rate at temperatures of 22°C and 60°C, but for the temperature of 100°C this material property increases when the strain rate increases. At 150°C the investigated SHCC loses its ductility and no noticeable strain rate effect can be observed. Furthermore, the residual properties of SHCC were evaluated using uniaxial tensile tests at room temperature on the specimens which were previously heated to 60°C, 100°C or 150°C. The residual tests showed that the strength, strain capacity, and work-to-fracture decrease with increasing pre-treatment temperature. However, in comparison with the results of the in-situ tests with elevated in-situ temperatures, the residual tests on SHCC yielded higher tensile strength and lower ductility. These results and possible mechanisms leading to changes in mechanical performance are discussed on the basis of the observed crack patterns on the specimens' surfaces as well as the microscopic investigations of the condition of fibers on fracture surfaces.