全再生骨料混凝土基本特性及受压损伤本构

Basic Property and Compressive Damage Constitutive Model of Full Recycled Aggregate Concrete

摘要:

为实现废弃混凝土资源最大化利用和充分挖掘其低碳潜能，提出发展全再生骨料混凝土（FRAC），即利用废弃混凝土加工成的再生粗、细骨料全部取代天然砂石制备的混凝土。以4种不同的骨料体系作为参变量，完成了FRAC的力学性能、收缩特性和单轴抗压应力-应变关系试验研究。分析结果表明，混凝土抗压强度受再生骨料体系，尤其是全再生细骨料的负面影响较大，但经过配合比优化，FRAC能满足C30强度等级以上的制备设计要求；全再生骨料体系增加了混凝土的干燥收缩，尤其是早期收缩发展；FRAC在单轴受压作用下出现较小变形时，损伤就开始明显发展，通过考虑初始损伤和受力损伤，建立了适用于FRAC的受压损伤本构模型，能很好地描述其应力-应变行为特征。最后，对提升全再生骨料混凝土力学性能未来需要开展的研究方向进行了展望。

关键词:全再生骨料混凝土（FRAC）;再生粗骨料;再生细骨料;力学性能;收缩;损伤本构关系

Abstract:

To realize the maximum and low-carbon utilization of waste concrete resources， a novel full recycled aggregate concrete （FRAC） was proposed， i.e.， using the recycled coarse and fine aggregates processed from waste concrete to replace natural sand and gravel to prepare new concrete. Taking four different aggregate combinations as parameter variables， the mechanical properties， shrinkage characteristics， and uniaxial compressive stress-strain relationship of FRAC were experimentally studied. The results show that the recycled aggregate combinations have an adverse effect on the development of concrete compressive strength， especially for concrete with full recycled fine aggregate. But by adjusting the mixing proportion， the FRAC can meet the design requirement for strength grade above C30. The full recycled aggregate combination increases the drying shrinkage of concrete， especially at the early stages. When FRAC has a small deformation under uniaxial compression， the damage began to develop and accumulate obviously. By considering the initial damage and mechanical damage， a damage constitutive model for FRAC under compression was established， which could well describe its stress-strain behaviour. Finally， the future research direction of improving the mechanical properties of FRAC was prospected.

Key words:full recycled aggregate concrete(FRAC);recycled coarse aggregate;recycled fine aggregate;mechanical property;shrinkage;damage constitutive relationship