A Comprehensive Framework for the Design and Optimisation of Limestone-Calcined Clay Cement: Integrating Mechanical, Environmental, and Financial Performance

Limestone-calcined clay (LC3) cement has emerged as a promising low-carbon alternative to ordinary Portland cement (OPC), offering significant potential to reduce carbon emissions while maintaining comparable mechanical performance. However, the absence of a prediction model for the formulation of the LC3 system presents challenges for optimisation within the evolving concrete industry. This study introduces a multi-objective optimisation (MOO) framework to design the optimal LC3 system, aiming to maximise compressive strength while minimising environmental and economic costs, simultaneously. The MOO framework integrates a regularised multivariate polynomial regression (MPR) model, achieving an R2 of 0.927 and MSE of 3.445 for mechanical performance prediction. Additionally, life cycle assessment quantifies the environmental impact, and collected market prices contribute to financial considerations of the LC3 system. Utilising a dataset of 366 LC3 mortar mixtures, the optimisation challenges the conventional 2:1 calcined clay-to-limestone ratio (CC:LS). For high strength (≥65 MPa), target a CC:LS ratio of 1:1 to 1.6:1; for lower strength (<65 MPa), increase calcined clay content, resulting in a CC:LS ratio of 1.6:1 to 2:1. The proposed framework serves as a valuable starting point to enhance the efficiency of LC3 system design and help decision-making to achieve desired mechanical, economic, and environmental objectives.