Generation and Numerical Analysis of Random Aggregate Structures in Recycled Concrete Aggregate Systems

A computational modeling procedure for generating a random aggregate structure (RAS) for recycled concrete aggregate (RCA) materials is proposed in this paper. The two-dimensional aggregate generation was based on a convex hull algorithm to randomize arbitrary planar shapes of RCA particles. During the generation of RAS, randomizations of the maximum aggregate size and spatial distribution of RCA particles were considered. Finite-element models for RCA systems were generated based on an extensive image analysis procedure. Numerical analyses were performed for 12 different RCA systems including crushed-shape and rounded-shape aggregates by varying the morphological parameters of the RCA particles. The mechanical performance of RCA systems with different particle shapes, maximum aggregate sizes, adhered mortar content levels, and aggregate ratios were used as factors to evaluate the mechanical performance of RCA systems under simulated compressive loading. Numerical results were compared with experimental studies from a large statistical database. The numerical simulation results for the mechanical properties of RCA systems showed represented experimental behavior such as the simulated elastic moduli and compressive strengths were within one and two standard deviations, respectively, of experimental results from a robust data set obtained through a detailed literature investigation. The proposed aggregate generation approach and numerical simulation procedure can be used by researchers to better understand how aggregate morphological properties influence the mechanical behavior of concrete made with recycled aggregates.