硫酸盐与冻融环境下混凝土本构关系研究

中文摘要: 为了研究硫酸盐与冻融环境下混凝土单轴受压应力—应变关系，对水中和质量分数为5%硫酸钠、5%硫酸镁溶液中冻融作用下的混凝土进行单轴受压试验，分析了硫酸盐溶液与冻融循环对混凝土峰值应力、峰值应变、弹性模量及单轴受压应力—应变全曲线的影响，并对损伤层混凝土的力学性能进行分析。结果表明：混凝土应力—应变曲线随冻融时间增加逐渐趋扁平，整体右移，硫酸盐溶液中冻融300次后的混凝土应力—应变曲线上升段轻微上扬，并出现下凹现象。随着冻融次数增加，混凝土峰值应力、弹性模量不断下降，峰值应变逐渐增加，硫酸镁溶液中混凝土表现更明显，混凝土抗冻性最差。通过回归分析，建立了硫酸盐与冻融循环作用下混凝土单轴受压应力—应变全曲线方程，并得到了不同冻融次数下损伤层混凝土峰值应力的确定方法。
Abstract:In order to study the stress-strain relationship of concrete under sulfate attack and freeze-thaw cycles, the uniaxial compression experiments of concrete subjected to freeze-thaw cycles in water, and mass fraction of 5% sodium sulfate, 5% magnesium sulfate solution were carried out. The effects of sulfate solution and freeze-thaw cycles on the peak stress, peak strain, elastic modulus and stress-strain curve of concrete were investigated．Furthermore, the mechanical property of the damage layer of concrete was analyzed. The results show that the stress-strain curve is flat and moves to the right with freeze-thaw time increases. The rising step of stress-strain curve rises slightly, and the curve is concave when concrete subjected to 300 freeze-thaw cycles in the sulfate solution. Along with the freeze-thaw cycle increases, the peak stress and elastic modulus of concrete decrease, and the peak strain increases gradually. This phenomenon is more obvious when concrete exposed to magnesium sulfate solution, and the frost resistance of concrete is the worst. Through regression analysis, the uniaxial compressive stress-strain curve equation under sulfate solution and freeze-thaw cycles is proposed to fit the test results. Moreover, the peak stress of the damage layer of concrete is obtained when exposed to different freeze-thaw cycles.