SHCC冻融后单轴压缩力学性能及损伤机理研究

Study on the uniaxial compressive behavior and damage mechanism of SHCC after freezing and thawing

采用棱柱体试件,研究冻融后应变硬化水泥基复合材料(SHCC)单轴压缩性能,分析冻融循环对其相对动弹性模量、质量、破坏模式、抗压强度及应力应变曲线的影响。结合电镜扫描结果,从微观揭示其劣化机理。结果表明:随着冻融循环次数增加,试件内部微结构逐步劣化,相对动弹性模量和抗压强度明显降低,单轴压应力应变曲线斜率逐渐减小,峰值应变则逐步增大。提出的冻融损伤模型具有较高拟合精度,能较好反映SHCC冻融损伤演化规律。

Investigations on the uniaxial compressive behaviors of strain hardening cementitious composites(SHCC)after freezing and thawing cycle were carried out in this research with the prism specimens.The relative dynamic elastic modulus,mass loss rate,uniaxial compressive strength,failure mode and stress-strain curves under uniaxial compression were determined for SHCC exposed different freeze-thaw loading cycles.Scanning electron microscope(SEM)was used to analyze the degradation mechanism of SHCC.The experimental results indicated that with the increase of the number ofthe freezing-thawing cycles,the internal microstructure of SHCC deteriorated gradually,the relative dynamic elastic modulus,the uniaxial compressive strength and the slope of stress-strain curves under uniaxial compression showed downward trends,while the peak strain gradually increased.Finally,an onlinear freeze-thaw damage model was proposed based on the experimental results,which had high precision to evaluate the damage evolution of SHCC exposed to freezing-thawing environment.