Abstract
Recycled concrete aggregate (RCA) is a typical construction and demolition (C&D) material generated in civil engineering activities and has been widely used as the coarse-grained filler added to sand for roadbed fillings. The effect of RCA content on the mechanical behavior of sand–RCA mixtures is complicated and still not fully understood. To explore the effect of RCA content on the macroscale and microscopic behavior of the sand–RCA mixtures with various RCA contents, laboratory direct shear tests and numerical simulations using the 3D discrete element method were performed. Experimental direct shear tests on sand–RCA mixtures with different contents of RCA were first carried out. Numerical direct shear models were then established to represent the experimental results. The particle shape effect was also considered using a new realistic shape modeling method to model the RCA particles. Good agreement was observed between the DEM simulation and experimental results, verifying the ability of the numerical direct shear models to represent the direct shear behavior of sand–RCA mixtures. The macroscopic responses of both experimental and numerical tests showed that all samples presented an initial hardening followed by a post-peak strain softening. The peak-state friction angles increased with the RCA content for samples under the same vertical stress. The effect of RCA content on the microscopic behavior based on DEM simulation was also found. The microscopic properties of RCA–sand mixtures, such as coordination numbers, PDFs and contact force transformation features, were analyzed and related to the macroscopic results.
Highlights
With the rapid urbanization and the ever-increasing population worldwide in recent years, an enormous amount of construction and demolition waste has been produced due to the ongoing civil engineering activities [1,2,3,4], which is causing serious environmental problems and threatening the sustainability of the modern society [5,6,7]
It is observed that the macroscopic behavior of all specimens with various Recycled concrete aggregate (RCA) content shows an initial strain hardening and post-peak softening behavior
The mechanical behavior of RCA–sand mixtures was investigated by using the direct shear test and the 3D discrete element method
Summary
With the rapid urbanization and the ever-increasing population worldwide in recent years, an enormous amount of construction and demolition waste has been produced due to the ongoing civil engineering activities [1,2,3,4], which is causing serious environmental problems and threatening the sustainability of the modern society [5,6,7]. Many researchers have investigated the performance of RCA as coarse aggregates blended with different types of fine particles. Many researchers have paid attention to the effect of coarse aggregate on the mechanical performance of the binary mixture using triaxial tests [24,25,26], direct shear tests [27,28] and simple shear tests [29,30] Another tool to study the mechanical behavior of binary mixtures is the discrete element method. This study conducted a systematic investigation of the effect of RCA content on the shear behavior of sand–RCA mixtures using laboratory tests and 3D DEM simulation. The densities of sand and RCA particles were 2.70 and 2.50 g/cm, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
