机制砂混凝土的冻融和盐侵蚀耐久性

对机制砂混凝土进行了冻融循环试验。考虑了三种强度等级(C30、C40、C50)和四种介质(清水、质量分数为5%的氯化钠溶液、质量分数为5%的硫酸钠溶液和5%氯化钠溶液+5%硫酸钠溶液组成的混合盐溶液)。重点考察质量损失率、相对动弹性模量和抗压强度的变化。结果表明:随着冻融循环次数的增加,四种环境下机制砂混凝土的质量、相对动弹性模量和抗压强度均呈下降趋势;盐的存在加剧了机制砂混凝土在冻融循环过程中产生的表层剥落,却减缓了机制砂混凝土相对动弹性模量的下降;盐溶液种类对机制砂混凝土冻融后质量损失率和相对动弹性模量的影响程度不同,氯化钠比硫酸钠的破坏力强。

Durability of Manufactured-Sand Concrete under the Combined Action of Salt Erosion and Freeze-Thaw Cycle

Experiment of freeze-thaw cycle on manufactured-sand concrete were carried out, considering grades of C30, C40, and C50 and solutions of 5 wt % Na2SO4, 5 wt % NaCl, mixture of 5 wt % Na2SO4 and 5 wt % NaCl, and pure water. Three parameters are studied: the rate of mass loss, the relative dynamic modulus of elasticity and compressive strength. The results indicate that with the increase of freeze-thaw cycles, the three parameters under every condition decline in different degree respectively. The salt in the solution exacerbate the surface spalling of concrete with manufactured-sand in the process of freeze-thaw cycle, but slow down the decline of the relative dynamic modulus of elasticity. The types of salt solution have different influence on the mass loss and the relative dynamic modulus of elasticity of concrete with manufactured-sand after freeze-thaw cycles. The method of improving concrete strength does not necessarily improve its frost resistance, the NaCl was more destructive than Na2SO4.