再生粗骨料混凝土静动态抗压强度离散性试验研究

Experimental investigation on discreteness of quasi-static and dynamic compressive strength of recycled aggregate concrete

为研究再生粗骨料(RCA)替代率和应变率对再生粗骨料混凝土(RAC)抗压强度离散性的影响,制备了3种不同RCA替代率的RAC (0%、50%、100%),分别进行准静态压缩及霍普金森压杆(SHPB)试验,与概率统计分析理论,对RAC抗压强度结果进行分析讨论。结果表明:准静态压缩下,RAC抗压强度离散程度随RCA替代率增加变化不显著,但表现出先增加后减小的趋势;SHPB试验应变率为50~120 s-1时,受RCA替代率和应变率的共同影响,同一应变率下RAC动态抗压强度离散程度随RCA替代率增加而增加,同一RCA替代率下RAC动态抗压强度离散程度随应变率增加逐渐减小。此外,对传统Weibull分布模型引入替代率和应变率参数进行修正,考虑到抗压强度离散性可能影响结构设计的安全性,提出了在任意保证率下具有不同RCA替代率的RAC动态抗压强度预测公式。

To explore the influence of the substitute rate of recycled coarse aggregate(RCA)and strain rate on the discreteness of the compressive strength of recycled aggregate concrete(RAC),RAC specimens with three different RCA substitute rates were prepared for both quasi-static compression and split Hopkinson pressure bar(SHPB)tests.The test results show that despite the limited change in the discreteness of compressive strength of RAC with increasing RCA substitution rate,it still tends to initially increase and then decrease as the RCA substitution rate increases.The results of the SHPB test indicate that both the RCA substitute rate and the strain rate exert a significant influence on the variability of the dynamic compressive strength of RAC.The dynamic compressive strength discreteness of RAC with the same RCA substitute rate gradually decreases with increasing strain rate,while it increases with increasing RCA substitute rate under the same strain rate.In addition,the traditional Weibull distribution model was modified by introducing the parameters of RCA substitute rate and strain rate,and a dynamic compressive strength prediction formula for RAC with different RCA substitute rates at any given probability level was proposed.