不同强度废旧混凝土水泥稳定再生材料路用性能研究

为了研究废旧混凝土强度与再生集料性能及水泥稳定再生基层材料的力学及耐久性能之间的影响规律,采用钻芯法对废旧桥梁T梁、立柱、废旧路面混凝土不同结构部位取样进行抗压强度试验,得出废旧混凝土的强度推定值,分别为25.8 MPa、37.4 MPa、58.1 MPa。对3种不同强度废旧混凝土再生集料的性能进行对比,并分析了不同强度废旧混凝土对再生集料性能及水泥稳定再生材料力学和耐久性能的影响。结果表明:废旧混凝土强度增加,再生集料的压碎值、针片状含量、吸水率减小,塑限指数及相对表观密度增大;废旧T梁、立柱、路面混凝土水泥稳定再生材料最佳含水率及最大干密度分别近似的呈线性减小和增大的趋势;同时,无侧限抗压强度、劈裂强度、抗压回弹模量、抗冲刷性能均表现增大的变化规律,但干缩性能减弱。废旧混凝土强度增加能有效提高水泥稳定再生材料的路用性能。

Road Performance of Cement Stabilized Recycled Materials with Different Strength Waste Concrete

In order to study the influence law among the strength of waste concrete, the performance of recycled aggregate and the mechanical and durability performance of cement stabilized recycled base material, the compressive strength of different parts of the waste bridge T-beam concrete, waste bridge column concrete, and waste pavement cement concrete was tested. The estimated strength values of these three kinds of waste concrete were 25.8 MPa, 37.4 MPa, and 58.1 MPa. The effects of three kinds of waste concrete with different strength on the properties of recycled aggregate and mechanical and durability of cement stabilized recycled materials were analyzed. The results show that with the increase of the strength of waste concrete, the crushing value, the content of needle and flake particles, water absorption, liquid limit and plastic limit of recycled aggregate are decreased, but the plastic limit index and the relative apparent density is increased. With the increase of the strength of waste concrete, the best content of cement stabilized recycled mixture is obtained. The water absorption and relative apparent density of recycled aggregate are not affected by the strength.Besides, the best water ratio and the maximum dry density are approximately linear decreasing and increasing respectively. When the strength of waste concrete is increasing, the unconfined compressive strength at 7 d, 28 d, 90 d, and 180 d, the splitting strength at 7 d,28 d, and 90 d, and the compressive resilience modulus at 28 d and 90 d are increased about the waste bridge T-beam concrete, waste bridge column concrete, and waste pavement cement concrete. Moreover, the dry shrinkage water loss rate of the mixture and the dry shrinkage performance is also decreased. And the mass loss rate of the erosion test is reduced and the anti-erosion performance is enhanced. Overall, increasing the strength of waste concrete can effectively improve the road performance of cement stabilized recycled materials.