掺锂渣再生混凝土三点弯曲梁双K断裂特性

Double K fracture characteristics of recycled concrete three-point bending beam mixed with lithium slag

为研究锂渣掺量和再生粗骨料取代率对掺锂渣再生混凝土双K断裂韧度的影响规律,试验制作了锂渣掺量分别为0%、10%、20%和再生粗骨料取代率分别为0%、30%、50%的9组配比36根掺锂渣再生混凝土标准三点弯曲梁进行断裂测试,并在分析裂缝扩展过程的基础上提出了混凝土断裂韧度预估模型。试验结果表明:随着再生粗骨料取代率的增大,混凝土双K断裂韧度均呈现先增大、后减小的趋势;锂渣的掺入可以提高混凝土的双K断裂韧度,且在一定程度上弥补高再生粗骨料取代率导致混凝土断裂韧度小的不足;锂渣掺量为20%、再生粗骨料取代率为30%时,混凝土双K断裂特性最优,起裂韧度和失稳韧度分别为0.54 MPa·m^(1/2)和1.07 MPa·m^(1/2),较基准组分别提高了42.1%和23%。

To study the effects of different lithium slag contents and recycled coarse aggregate percentages on the double-K fracture toughness of recycled concrete with lithium slag, 36 standard three-point bending beams of recycled concrete with lithium slag, which include 9 mix ratios about lithium slag content of 0%,10%,20% and recycled coarse aggregate percentage of 0%,30%,50%, were prepared for fracture test.Based on the analysis of crack propagation process, a prediction model for fracture toughness of concrete was proposed. The research results show that the double K fracture toughness of concrete all increases first and then decreases with the increase of the recycled coarse aggregate percentage. The addition of lithium slag can improve the double K fracture toughness of the concrete and offset the deficiency of the concrete fracture performance with high recycled coarse aggregate percentage. The double K properties are optimal when the lithium slag content and recycled coarse aggregate account for 20 % and 30 % respectively. The initial fracture toughness and unstable fracture toughness reach 0.54 MPa·m^(1/2)and 1.07 MPa·m^(1/2),increasing by 42.1% and 23 % respectively compared with the reference group.