考虑粗骨料品质和取代率的再生混凝土抗压强度计算

再生混凝土的粗骨料表面存在硬化砂浆和大量的界面结构，致使其抗压强度较普通混凝土的有所降低，且受压破坏情况更为复杂。为建立一个普遍适用的再生粗骨料混凝土抗压强度计算公式，试验中采用不同再生粗骨料品质、不同取代率的再生混凝土，研究了胶水比、再生粗骨料的品质和取代率对再生混凝土抗压强度的影响，并分析了再生粗骨料吸水率、表观密度和压碎指标等品质特征参数和其影响因子的相关性。在普通混凝土Bolomey抗压强度公式的基础上，建立了考虑骨料品质和取代率的再生粗骨料混凝土抗压强度计算公式，并与常用的抗压强度计算公式的计算结果进行了误差比较。研究结果表明：再生粗骨料混凝土抗压强度与胶水比、取代率之间均呈线性关系，并且再生粗骨料的品质对再生混凝土抗压强度影响显著；误差分析表明，与试验结果相比，普通混凝土Bolomey抗压强度公式的最大误差约为16.51%，考虑有效胶水比的再生粗骨料混凝土抗压强度的最大误差约为36.33%，而考虑再生粗骨料品质差异和取代率的再生混凝土抗压强度的最大误差仅为4.90%，具有较高的精度和较好的适用性。

Calculation of compressive strength of recycled concrete based on coarse aggregate quality and replacement rate

Due to the existence of hardened mortar and a large number of interface structures on the surface of recycled coarse aggregate, the compressive strength of recycled concrete is lower than that of ordinary concrete, and the compressive failure mechanism is much more complicated. To establish a universal calculation formula for compressive strength of recycled coarse concrete, recycled concrete was prepared by three kinds of recycled coarse aggregates with different replacement rates in the experiment. The effect of binder-water ratio and quality and replacement rate of recycled coarse aggregate on the compressive strength of recycled concrete was studied systematically, and the correlation between the water absorption, apparent density and crushing index of recycled coarse aggregate and its influence factors was analyzed. Based on the Bolomey compressive strength formula of normal concrete, the formula of compressive strength of recycled coarse aggregate concrete based on aggregate quality and replacement rate was established and compared with the commonly used compressive strength formula in terms of error comparison. The results show that it has a linear relationship between the compressive strength of recycled coarse aggregate concrete and the binder-water ratio and replacement rate. The quality of recycled coarse aggregate has a significant effect on the compressive strength of recycled concrete. The error analysis shows that, compared with the test results, the maximum calculation error of Bolomey formula for the compressive strength of ordinary concrete is about 16.51%, and the maximum calculation error of the compressive strength of recycled coarse aggregate concrete based on effective binder-water ratio is about 36.33%, but the maximum calculation error of the compressive strength of recycled concrete based on different quality and replacement rate of recycled coarse aggregate is only 4.90%. Therefore, the newly established compressive strength formula of recycled coarse aggregate concrete has higher accuracy and better applicability.