结构型钢纤维对盐-冻融耦合作用下混凝土损伤的影响

为探究钢纤维在氯盐侵蚀与冻融循环耦合作用下对混凝土损伤的影响，对多组不同钢纤维掺量的混凝土试件进行快速盐-冻融循环试验。利用超声波法和激光扫描法分析不同掺量盐-冻融后混凝土损伤的效应，通过分析超声波速变化得到混凝土的盐-冻融损伤度D，并建立D与盐-冻融循环次数n之间的韦布尔分布；利用混凝土表面的粗糙度表征混凝土表面损伤，并研究了不同掺量钢纤维混凝土试件表面在盐-冻融循环作用后粗糙度变化率ΔR的作用，以及ΔR与D的函数关系。结果表明：混凝土盐-冻融损伤随着钢纤维掺量的增加而减小；基于超声波法建立的损伤度D与盐-冻融循环次数之间较好地满足两参数韦布尔分布，决定系数大于0.95；混凝土试件损伤度D随粗糙度变化率ΔR的变化规律满足指数函数关系，决定系数大于0.80。

Effect of macro steel fiber on damage of concrete after salt freeze-thaw cycle

In order to reveal the influence of salt erosion and freeze-thaw cycle coupling effect of steel fiber on concrete damage evolution, four groups of concrete specimens with different mass fractions of steel fiber were tested under salt freeze-thaw test. The damage of concrete after salt freeze-thaw cycles was analyzed by ultrasonic method and laser scanning method. The damage degree D of concrete after salt freeze-thaw cycles was obtained by analyzing the change of ultrasonic wave velocity. The Weibull distribution model between D and freeze-thaw cycles n was established. The surface roughness was used to characterize the surface damage of the concrete. The change rate of roughness ΔR of concrete with different steel fiber dosage was studied as a function of freeze-thaw cycles. The results indicate that the damage of concrete decreases with the increase of steel fiber dosage. The relationship between D and n established by ultrasonic method satisfied the two-parameter Weibull distribution model, and the determination coefficient is higher than 0.95. It has an exponential relationship between D and ΔR due to its determination coefficient higher than 0.80.