废弃纤维再生混凝土黏结性能试验

为了研究废弃纤维再生混凝土与钢筋的黏结性能,选取再生骨料替代率(0%,25%,50%,75%,100%)、废弃纤维体积掺量(0%,0.12%,0.24%)为试验变量,制备7组共14个试件,进行半梁式单向拔出试验。根据试验结果,分析了再生骨料替代率和废弃纤维体积掺量对混凝土极限黏结应力和极限滑移量的作用机理。结果表明:再生骨料的加入降低了混凝土的黏结性能,但并未改变混凝土与钢筋原有的破坏方式,其黏结应力随再生骨料替代率的增加而下降,滑移量随再生骨料替代率的增加先降低后升高; 废弃纤维的加入优化了再生混凝土与钢筋的黏结接触界面,提升了再生混凝土与钢筋的黏结性能; 体积掺量0.12%的废弃纤维对黏结性能的提升效果最为明显; 建立的废弃纤维再生混凝土极限黏结应力预测公式的计算结果与试验结果拟合良好,为进一步研究废弃纤维再生混凝土与钢筋的黏结性能和黏结应力预测奠定了基础。

Test on Bonding Behavior of Waste Fiber Recycled Concrete

In order to study the bonding behavior of waste fiber recycled concrete and steel bars, 7 groups and 14 specimens were prepared, and a half-beam unidirectional pullout test was carried out with the replacement rate of recycled aggregates of 0%, 25%, 50%, 75%, 100% and the volume of waste fibers content of 0%, 0.12%, 0.24%. According to the test results, the effective mechanism of the replacement rate of recycled aggregate and the volume of waste fiber on the ultimate bond stress and ultimate slip of concrete was analyzed. The results show that the addition of recycled aggregates was harmful to the bonding behavior of concrete, but does not change the original failure mode of concrete and steel bars. The bonding stress decreases with the increase in the replacement rate of recycled aggregates. The amount of slip decreases firstly and then increases with the increase in the replacement rate of recycled aggregate. With the addition of waste fiber, the bonding interface between recycled concrete and steel bars is promoted, and the bonding behavior of recycled concrete and steel bars is improved. The waste fiber content of 0.12% has the most noticeable improvement effect on the bonding performance. The calculation result of the proposed prediction formula for the ultimate bond stress of waste fiber recycled concrete are in good agreement with the experimental data, which establishes a foundation for further research on bonding behavior and stress prediction of waste fiber recycled concrete and steel bars.