Evaluation of mechanical properties and carbonation of mortars produced with construction and demolition waste

The large amounts of waste generated by the construction sector pollute the environment owing to a lack of suitable disposal sites for construction and demolition waste (CDW) and improper methods of disposal. However, these problems provide an incentive to develop recycling alternatives. In pursuit of such alternatives, this study compares the mechanical properties and carbonation depths of mortars produced with two different types of recycled aggregates (RAs): ceramic recycled aggregate (CRA) and mixed recycled aggregate (MRA). The mechanical properties (compressive, flexural, and adhesive strengths), physical properties (porosity, water absorption, and bulk density), carbonation depth over time, and CO2 uptake were evaluated for mortars made with both the types of aggregates. The mortars evaluated were mixed with different levels of RAs used to replace the natural aggregate (25%, 50%, 75%, and 100%). The results showed that as the natural aggregate was replaced with greater portions of RA materials, the compressive strengths of the mortars were reduced, and increases in the carbonation depths of the mortars were observed for all the sample ages analyzed. The results indicated that the bond strength of a mortar with CRA was higher than that of the natural aggregate reference mortar. The mortars produced with CDW exhibited higher CO2 uptake potential, being able to sequester up to 170 g.CO2/m2 of coating. Overall, this study illustrated that the use of CDW as a source of fine mortar aggregates can be considered a valid and sustainable alternative for use in construction.