硫酸盐干湿循环对再生骨料混凝土性能的影响

Effect of Sulfate Dry-Wet Cycles on the Performance of Recycled Aggregate Concrete

为了探讨再生骨料混凝土在硫酸盐作用下的耐久性能,选取再生粗骨料替代率为50%、100%的两组再生混凝土和普通骨料混凝土进行硫酸盐环境中的干湿循环试验。从侵蚀后混凝土表观形貌,质量、强度、超声波速经时变化规律分析混凝土的损伤特性。结果表明:再生骨料混凝土抗硫酸盐侵蚀能力小于普通骨料混凝土,且抗侵蚀能力随着再生骨料替代率的增加而降低。硫酸盐侵蚀后,混凝土质量、强度、超声波速经时变化曲线由上升段与下降段两部分组成。超声波法可以反映再生骨料混凝土侵蚀后的损伤特征。最后,建立了无量纲化超声波速与抗压强度之间的演化方程。

To study durability of recycled aggregate concrete with the help of sulfate, the experiment of dry-wet cycle based on recycled aggregate concrete of which was 50 and 100 percent of replacement rates with two groups of recycled aggregate concrete and natural aggregate concrete. The damage development was evaluated by apparent characteristics of attacked concrete under the condition of sulfate, mass, compressive strength and ultrasonic velocity changes over erosion time. The results showed that the sulphate-resistance of recycled aggregate concrete is not as good as natural aggregate concrete. And the ability of erosion resistance is decreasing with the increase of the replacement ratio of recycled aggregate. After the erosion of sulfate, the change curve is ascending and descending, in which the mass, compressive strength and ultrasonic velocity of concrete are related with time. The method of ultrasonic reflects the damage feature of recycled aggregate concrete after the erosion of sulfate. As a result, the evolution equation of dimensionless ultrasonic and compressive strength was built.