水泥稳定再生粗集料级配设计方法研究

为解决国内地方规范中水泥稳定再生粗集料级配范围较大的问题,以粒子干涉理论与最大密度曲线理论为基础,分析总结再生粗集料、天然细集料的比例及骨架密实型水泥稳定再生粗集料的合理级配范围,同时与地方规范推荐级配的水泥稳定再生粗集料的击实特性和抗压性能进行比较。结果表明:当天然细集料与再生粗集料含量之比为30%~60%时,粗集料间形成紧密嵌挤的骨架结构,内摩阻角大,天然细集料和水泥水化产物充分填充,黏聚力强,形成了骨架密实的水泥稳定再生粗集料,7 d无侧限抗压强度>3.0 MPa;水泥剂量为5%时,设计级配的水泥稳定再生粗集料的击实特性和抗压性能优于地方规范推荐级配。

Design Method for Gradation of Cement-stabilized Recycled Coarse Aggregate

In some local specifications in China, the gradation of cement-stabilized recycled coarse aggregate distributes in a wide range. In view of this, in the light of the particles interference theory and the maximum density curve theory, we analyze the proportion of recycled coarse aggregate and natural fine aggregate, and summarize the reasonable range of the gradation of skeleton-dense cement-stabilized recycled coarse aggregate. We also compare the compaction characteristic and compressive performance with those recommended in local specifications. Results reveal that when the content ratio of natural fine aggregate to recycled coarse aggregate is 30%-60%, a tightly packed framework structure is formed between coarse aggregates, giving rise to large internal friction angle; the natural fine aggregate and cement hydration product are fully filled, resulting in large cohesive force and skeleton-dense cement stabilized recycled coarse aggregate. The unconfined compressive strength at 7-d age is higher than 3.0 MPa. When cement dosage is 5%, the compaction characteristics and compressive performance of the design graded cement stabilized recycled coarse aggregate are better than those recommended by local specification.