Life Cycle Assessment of Sugarcane and Energy Cane Ashes as Supplementary Cementitious Materials in Portland Cement Mortars

The cement industry accounts for approximately 8–9% of global greenhouse gas emissions, mainly due to clinker production. Replacing Portland cement with supplementary cementitious materials (SCMs) is a promising strategy to reduce these environmental impacts. This study evaluates the mechanical performance and environmental profile of sugarcane ash (SCA) and energy cane ash (ECA) as SCMs in Portland cement mortars. To the best of the authors’ knowledge, this is the first study to integrate the mechanical performance and life cycle environmental assessment of energy cane ash as a supplementary cementitious material in Portland cement mortars. Mortars incorporating 5–20% ash were tested for compressive strength and accelerated carbonation. An attributional life cycle assessment (LCA), following ISO 14040/44 and using the ReCiPe 2016 method, was conducted with a cradle-to-gate approach. At 28 days under wet curing, 10% ECA replacement achieved slightly higher compressive strength than the reference mortar (102%), while 10% SCA replacement also achieved compressive strength similar to the reference mortar, although slightly lower than that of ECA. Both ashes significantly reduced carbonation depth, indicating improved durability. From a life cycle assessment perspective, replacing cement with 10–20% ECA reduced environmental impacts in nine of the ten impact categories evaluated, including climate change (up to 18.6%), fossil depletion, and metal depletion. SCA also improved most categories, although to a lesser extent. The superior performance of ECA is associated with its higher biomass yield and environmental credits from potassium recovery during ash washing. These results demonstrate that agro-industrial ashes, particularly energy cane ash, can enhance mortar performance while reducing environmental burdens, mitigating industrial waste accumulation, and supporting circular economy strategies and climate change mitigation, thereby offering a viable pathway toward more sustainable cement production.