Impact of Curing Temperature on the Life Cycle Assessment of Sugarcane Bagasse Ash as a Partial Replacement of Cement in Mortars

Abstract

Sugarcane bagasse ash (SCBA), a biomass waste resulting from sugarcane bagasse burning for electricity production, has shown to be a viable alternative option as a partial cement replacement due to its chemical composition and physical properties. Besides, previous research indicates that higher curing temperature may improve the mechanical properties of mixes containing SCBA as cement replacement. However, the environmental assessment of those mixes is lacking in the literature. This study aims to understand how curing temperature impacts the Life Cycle Assessment (LCA) of SCBA as a partial replacement of cement in mortars. An LCA was performed from the extraction of the raw materials to the material production part of the life cycle, including transport. This study shows that the reduction of environmental impact when using SCBA highly depends on the curing temperature. When mortars were cured at 45 °C, the use of SCBA reduced the environmental impact of mortars two times with respect to the reduction at 21 °C (31% reduction when cured at 45 °C vs. 14% at 21 °C, with a 20% replacement). This difference is mainly related to the fact that the higher the curing temperature, the better SCBA mortars perform in terms of strength, thus, net savings of cement required to achieve a given performance are higher. Results indicate that the sustainability of SCBA utilization as a partial replacement of cement will be better when mortar is poured in hot regions or during days with higher ambient temperatures. Likewise, the advantages of using SCBA in terms of sustainability will decrease if the external temperature is low.