Experimental Study on Creep Failure of Non-Steam-Cured Ultrahigh-Performance Concrete under High Uniaxial Compressive Stress

Abstract

Ultrahigh-performance concrete (UHPC) creep failure was experimentally investigated under high uniaxial compressive stress. The influence of applied stress levels, loading times, and loading rates was considered. The failure mode, ultimate strain, creep coefficient, Poisson’s ratio, and nonlinear creep of UHPC were analyzed. The creep specimens failed suddenly in the tertiary creep stage. The ultimate strain of each creep failure specimen was less than the corresponding peak strain εc. The circumferential creep coefficient was considerably larger than the axial creep coefficient. In the loading phase, no significant increase in Poisson’s ratio was observed for specimens loaded at normal or rapid rates. In the creep phase, Poisson’s ratios increased considerably. The microcracks propagation within the specimens affected the nonlinear creep and creep failure behavior in UHPC specimens under high sustained compressive stress. An amplification factor model for the nonlinear creep strain was proposed, and was validated by comparing measured and calculated results.