Environmental and technical assessment of mortars produced with recycled aggregate from construction and demolition waste

Abstract

Circular economy technologies are entering several fields, especially engineering, without stopping. Recycled materials application, dematerialization, and carbon capture improvement can help achieve a more sustainable construction material and method. In this scenario, the present paper aims to evaluate the environmental and technical aspects of mortars produced with various replacement levels (25, 50, 75, and 100 %) of fine recycled aggregate from recycled aggregate (RA) from mixed construction and demolition waste (CDW). Physical (absorption by immersion, water absorption by capillarity, porosity, and pore size distribution) and mechanical properties tests (compressive strength, flexural tensile strength, and adhesive strength) were performed. The mortars were submitted to four carbonation environments for environmental analysis: accelerated in an open-circuit chamber with 3 % CO₂ and natural carbonation (internal, external-protected, and external unprotected). The carbon capture analysis was performed with TGA tests for carbonated and non-carbonated samples. The results were applied for mortar carbon index (MCI) calculations. The primary energy and water demand for these mortars were also analyzed. Results showed that mortars with 50 % RA had a better MCI (91.80 t.CO₂/MPa) for the externally protected environment, considering tensile adhesion strength as the main property. This happened due to better mechanical performance and higher carbon capture related to cement and limestone content in the mortar since these two are responsible for hydroxide presence. However, results showed more considerable primary energy demand and water consumption with the increase in replacement levels. With these results, the research allows the possibility to better plan the working schedule in building constructions and materials decision-making to help improve carbon capture and natural resources application in coating materials.