冻融环境下沙漠砂对混凝土轴心受压力学性能的影响

为研究沙漠砂对混凝土抗冻性能的影响,采用快速冻融方法,进行掺沙漠砂混凝土冻融后轴心抗压强度试验,得到不同冻融循环作用下掺沙漠砂混凝土破坏特征和应力-应变曲线,分析不同冻融循环下掺沙漠砂混凝土表面损伤特征、质量损失率、动弹性模量损失率和超声波波速损失率的变化规律.结果表明:随着冻融循环次数增加,掺沙漠砂混凝土质量损失率变化较小,动弹性模量损失率、超声波波速损失率、相对峰值应变和极限应变均增大,相对峰值应力和横向变形系数均减小,弹性模量先增大后减小;在相同冻融循环次数下,掺沙漠砂混凝土弹性模量损失率、超声波波速损失率和相对峰值应变均小于普通混凝土,相对峰值应力、横向变形系数和弹性模量比普通混凝土高.采用过镇海提出的单轴受压本构模型拟合得到应力-应变全曲线方程,分析冻融循环对应力-应变曲线控制参数的影响,可对沙漠砂混凝土结构的抗冻性能进行分析.

Influence of desert sand on axial compression behavior of concrete under freezing and thawing environment

To study the influence of desert sand on the frost resistance of concrete, the compression strength experiment of desert sand concrete after freezing and thawing test was carried out by rapid freeze-thaw method. The stress-strain curves and failure characteristics of desert sand concrete after different freeze-thaw cycles were obtained. The variations of surface damage characteristics, mass loss rate, dynamic elastic modulus loss rate, and ultrasonic wave velocity loss rate of desert sand concrete were analyzed. Experimental results show that with the increase of the number of freeze-thaw cycles, the mass loss rate of desert sand concrete had little change; the dynamic elastic modulus loss rate, ultrasonic wave velocity loss rate, relative peak strain, and ultimate strain increased; the relative peak stress and transverse deformation coefficient declined; the elastic modulus increased firstly and then decreased. With the same number of freeze-thaw cycles, the dynamic elastic modulus loss rate, ultrasonic wave velocity loss rate, and relative peak strain of desert sand concrete were less than those of ordinary concrete. However, the relative peak stress, transverse deformation coefficient, and elastic modulus of desert sand concrete were higher than those of ordinary concrete. On the basis of the uniaxial compression constitutive model of concrete put forth by Guo Zhenhai, the equation of stress-strain full curves was formulated. The influence of freeze-thaw cycles on the control parameters of stress-strain curves was analyzed, which can be applied for the frost resistance analysis of desert sand concrete structures.