再生砖细骨料混凝土的力学性能与孔隙结构

Mechanical Property and Pore Structure of Recycled Brick Fine Aggregate Concrete

摘要:

通过评价不同颗粒级配再生砖细骨料（RBFA）和天然河砂（RS）的物理特性差异，研究了RBFA颗粒级配和取代率对混凝土力学性能和孔隙结构的影响，并基于传统力学预测模型，构建RBFA混凝土抗压强度与弹性模量、劈裂抗拉强度的关系。结果表明：与RS相比，多孔特性使RBFA密度更低，饱和面干吸水率更高；RBFA的掺入导致混凝土的抗压强度和弹性模量降低，最大降幅分别达29.6%、29.0%；随着RBFA取代率的增加和粒径的增大，混凝土的力学性能持续下降，而RBFA细粉对其力学性能有改善作用；RBFA的掺入使混凝土无害孔、多害孔的占比以及孔隙率增大；拟合得到的RBFA混凝土力学性能预测模型误差较低，可实现力学性能的预测。

Abstract:

The physical differences between recycled brick fine aggregates（RBFA） with different particle size distributions and natural river sand（RS） were evaluated. The effects of particle size distribution and replacement ratio of RBFA on the mechanical property and pore structure of concretes were investigated. Based on classical mechanical prediction models， the relationships between compressive strength and elastic modulus， compressive strength and splitting tensile strength were established. The results show that compared with RS， the porous nature of RBFA leads to lower density and higher saturated surface-dry water absorption. The incorporation of RBFA reduces the compressive strength and elastic modulus of concretes， with a maximum decrease of 29.6% and 29.0% respectively. With the increase of RBFA’s replacement ratio and particle size， the mechanical properties of concretes decrease continuously. Moreover， the RBFA fine powder exerts an improving effect on the mechanical properties. The incorporation of RBFA increases the proportions of harmless pores and harmful pores， as well as the porosity of concretes. The fitted prediction model for the mechanical properties of RBFA concretes exhibits low prediction error， and the prediction of mechanical properties can be achieved.