Mortars with recycled aggregate of construction and demolition waste: Mechanical properties and carbon uptake

Abstract

Over the past few years, the use of recycled aggregate (RA) from construction and demolition waste (CDW) has proved to be a promising alternative for increasing the concept of a circular economy within the construction industry. RA contributes to an adequate destination for these wastes besides minimizing the use of natural aggregates (NA). Carbonation also has proved to be a promising alternative to carbon capture, use, and storage. This work aims to evaluate the substitution influence of NA for RA in replacement levels of 0, 25, 50, 75, and 100% with three different particle size distributions to evaluate the particle size influence. Compressive and tensile strength in bending, porosity, absorption, and bulk density were performed to evaluate physical–mechanical properties. The accelerated carbonation test and thermogravimetric analysis were carried out to evaluate the carbon uptake. X-ray microtomography test was carried out in addition to XRD analysis to assess the influence on microstructural properties. The particle size distribution interferes with the results, where washing the aggregate does not significantly improve the investigated properties. The mortar with the optimized properties contained particles between 2.4 mm and 0.15 mm (G2.4). The less emissive mortar was G2.4_100, which reabsorbs 63% of all the carbon dioxide released in production. The mortars with 100% replacement have a less emissive balance, and the replacement level increases the amount of CO2 captured. Cement-based mortars produced with RA can be an alternative for carbon capture due to mineralization from carbonation, promoting the circular economy using RA from CDW.