CO2 emissions and uptake in rendering mortars: sustainable approach

Abstract

This study aimed to estimate CO2 emission and uptake due to the mixed rendering mortars carbonation process, replacing natural aggregate (NA) with recycled aggregate (RA) and lime contents to produce less emissive final material. Mortars were subjected to natural carbonation in three environments. Carbonation depth was evaluated until 119 days of CO2 environmental exposure, and thermogravimetric analysis determined absorbed carbon content. The scenario evaluation considered different depths for the potential CO2 uptake. It was found that the higher the lime content, the higher the carbon emissions and capture. However, the CO2 captured amount (25.41 KgCO2/m³) does not balance its emission from raw materials production. Replacing NA for RA, the mortars reduced emissions associated with production by approximately 8.15%. The scenario simulation proved that constructive control is essential for rendering mortar depths less than 20 mm, the maximum carbon fixation is reached before rendering. Mortars with recycled aggregate are less emissive, which is essential in selecting more sustainable building materials.