Sustainability evaluation of concrete and mortar with plastic aggregates and supplementary cementitious materials: An integrated <scp>LCA</scp> – <scp>LCCA</scp> framework

Abstract The use of plastic waste as a sustainable substitute for natural aggregates in construction is gaining attention, alongside efforts made to develop alternative cementitious materials to reduce the environmental and economic impacts of conventional cement. This study evaluates the environmental and economic performance of recycled plastic waste aggregate (RPWA) and waste plastic aggregate as partial replacements for natural aggregates in concrete using Life Cycle Assessment, with and without mass allocation, and Life Cycle Cost Analysis (LCCA). The environmental and economic impacts were assessed for both conventional and alkali‐activated concrete (AAC) incorporating alternative cementitious materials. The results show that mass allocation significantly influences impact results and can overestimate the environmental burden of plastic aggregates. AAC mixes containing bauxite and GGBS exhibited the lowest global warming potential and human toxicity, as well as the lowest carbon emissions per unit compressive strength, while RPWA concrete with epoxy resin showed the highest emissions. LCCA indicated cost savings of US$ 29.52–29.59/m 3 for alternative binders and US$ 10.82–24.56/m 3 for plastic aggregate concrete. Sensitivity and uncertainty analyses identified transport distance, cement reduction, and aggregate selection as key drivers for minimizing CO 2 emissions and improving sustainability in concrete production.