Study on the Construction Waste Composition and Strength Mechanism of Recycled Mixture

Abstract

Recycling of construction waste has been a hot issue in road engineering research, and microscopic characteristics and composition of construction waste-recycled aggregate (RA) significantly influence their macroscopic service characteristics. In this paper, the composition, microstructure, and strength formation mechanism of natural aggregate (NA), recycled concrete aggregate (RCA), and recycled brick (RCB) were systematically studied by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), fractal dimension and porosity determination, unconfined compressive strength test, and indirect tensile test. The results showed that RA’s microscopic morphological characteristics and chemical components were analyzed by combining XRD and SEM electron microscopy techniques. RA has prominent fractal features, and the smaller bulk density and more extensive crushing value index of RA correspond to its larger porosity as well as fractal dimension. The attributes of RA lead to the peak of 7 d unconfined compressive strength and 7 d splitting strength of the mix. The reasonable control of RA admixture benefits the improvement of mix strength. This study relies on engineering to carry out theoretical and experimental research, which provides essential support and guarantee for the application of construction waste in the field of highway transportation in Hebei Province.

Optimization and mechanism analysis of a compound additive for unfired bricks made of construction and demolition wastes

“…Discarding these fine particles reduces the waste utilization rate and may cause severe secondary air and water pollution (Jannat et al, 2020;Limami et al, 2020;Limami et al, 2021). Unfired bricks are not picky about raw materials, and CDW fine particles contain a lot of active substances (Borrachero et al, 2022;Sanqiang et al, 2022). With the activation of additives (Villaquirán-Caicedo and Mejía de Gutiérrez, 2021), they can promote the strength of unfired bricks and save costs.…”