Impacts of high CDW levels on the chemical, microstructural, and mechanical behavior of cement-based mortars

Abstract

To minimize the environmental impacts of construction and demolition waste (CDW) generation, it is essential to investigate sustainable materials' chemical and microstructural aspects, such as fine recycled concrete aggregate into cement-based mortars. A comprehensive experimental program was conducted to evaluate workability, compressive strength, and microstructural characteristics, providing insight into sustainable applications in construction. In this sense, the main goal of the present work is to examine the mechanical behavior of mortars produced with CDW due to their potential for introduction into the civil construction market. The mortars were made to evaluate the mechanical behavior and characterization tests of recycled and natural aggregates, consistency index, mass density, resistance to simple compression, x-ray diffraction, and scanning electron microscopy. The results revealed that the grains' maximum characteristic dimension corresponds to 2.36 mm, equivalent to the fine sand used. However, the water absorption of the recycled aggregate was 20.1 %, which is higher than the water absorption of fine sand, which corresponds to 12.5 %. The 1:4 ratio with 30 % replacement content showed better workability and compressive strength of 44.92 MPa. However, the 1:7 ratio showed high consistency rates due to the water-cement ratio. Further, the XRD results revealed diffraction peaks associated with Quartz, Portlandite, and Ettringite phases, corroborating the technical feasibility of using CDW. Finally, high partial replacements of fine natural aggregate by fine recycled concrete aggregate have technical and sustainable. This work highlights its potential to reduce construction costs and environmental impact, contributing to the circular economy.