Abstract:Investigations on the residual uniaxial compressive behaviors of strain hardening cementitious composites with high volume of fly ash(HVFA SHCC) subjected to elevated temperatures were carried out. Specimens with dimension of 40mm×40mm×160mm were exposed to different temperatures(100,200,400,600,800℃). Residual compressive strength, stress strain curves, compressive toughness, elastic modulus and failure mode were determined after two cooling methods(natural cooling and water cooling). Scanning electron microscope(SEM) was used to analyze the degradation mechanism of HVFA SHCC at mesoscale level. Experimental results indicate that the temperature has little effect on the mechanical properties and mass loss of HVFA SHCC when temperature is lower then 200℃. At 400800℃, the internal micro structures of HVFA SHCC specimen become loose and the residual mechanical properties deteriorate seriously. When the temperature is higher than 800℃, the average residual compressive strength, the elastic modulus and the toughness index of the samples is only 399%, 323% and 590% of that at room temperature, respectively. And the mass loss rate is increased to 155%. Meanwhile, the effect of cooling method on residual mechanical properties is significant. The specimens cooled in water exhibit superior residual mechanical performance. Finally, based on the test results, the uniaxial compressive constitutive relationship of HVFA SHCC after high temperature is proposed.