Abstract

Recycled construction and demolition (C&D) materials are widely used in engineering fills to reduce the pressure on the environment. This study intended to investigate the effect of particle sizes and sand contents on mechanical behavior of recycled C&D materials using triaxial tests. The results demonstrated that the water absorption rate of crushed bricks (CB) was much higher than that of recycled concrete aggregate (RCA), and crushing value of recycled C&D materials was slightly lower than that of natural aggregate (NA). An appropriate amount of sand can effectively improve the particle gradation and maximum dry density of C&D materials. Results from the triaxial test showed that C&D materials with particle sizes smaller than 40 mm have higher porosity and lower strength than that of C&D materials with particle sizes smaller than 20 mm. At low porosity and confining pressure, the stress–strain curve followed a strain-softening trend. Under high confining pressure, the curve exhibited a strain hardening trend. After mixed with a suitable amount of sand, the soil changes from skeleton-void structure to suspended-dense structure, and the overall strength of specimens also increases. Finally, the modified power-law model was found to adequately describe the constitutive behavior of recycled C&D materials.

摘要

回收的建筑和拆除（C＆D）材料广泛用于工程填充物中，以减少对环境的压力。本研究旨在使用三轴试验研究粒度和含砂量对回收的拆建材料的机械性能的影响。结果表明，碎砖（CB）的吸水率远高于再生混凝土骨料（RCA），而再生拆建材料的破碎值略低于天然骨料（NA）。适量的沙子可以有效地改善C＆D材料的颗粒等级和最大干密度。三轴试验结果表明，与C＆D材料相比，粒径小于40 mm的C＆D材料具有更高的孔隙率和更低的强度。粒径小于20毫米的D材料。在低孔隙度和围压下，应力-应变曲线遵循应变软化趋势。在高围压下，曲线表现出应变硬化趋势。在掺入适量的沙子后，土壤会从骨架空洞结构转变为悬浮致密结构，并且试样的整体强度也会增加。最后，发现修改后的幂律模型可以充分描述再生C＆D材料的本构行为。并且样品的整体强度也增加了。最后，发现修改后的幂律模型可以充分描述再生C＆D材料的本构行为。并且样品的整体强度也增加了。最后，发现修改后的幂律模型可以充分描述再生C＆D材料的本构行为。