A holistic approach and frame work to optimized fly ash cement brick production integrating technical, life cycle cost and environmental life cycle assessment

The utilization of fly ash, a by-product of coal combustion, has gained significant attention in recent years due to its potential as a sustainable alternative to traditional cement in the construction industry. This study proposes a comprehensive and novel framework for the development of fly ash cement bricks (FACB), integrating technical performance optimization, environmental assessment, and economic viability analysis. A parametric investigation was conducted using the Taguchi orthogonal array design with three factors and levels, fly ash (50-70 %), cement (7.5-12.5 %), and water-to-binder ratio (20-24 %). A comprehensive environmental Life Cycle Assessment (LCA) with and without mass allocation to fly ash and Life Cycle Cost Analysis (LCCA) were conducted in accordance with ISO 14040/44 and ISO 15686 standards. Multi-parameter optimization was performed to achieve a target compressive strength of 10 MPa while minimizing water absorption, shrinkage, efflorescence, and Global Warming Potential (GWP). The optimal mix proportions were identified as 60 % fly ash, 10 % cement, and a 22 % (0.22) water-to-binder ratio and experimentally validated with a 95 % confidence interval, confirming the accuracy of the predicted response properties. The improved compressive strength and reduced water absorption were attributed to enhanced matrix densification from cement hydration, while lower shrinkage and efflorescence resulted from the filler effect and pozzolanic activity of fly ash. The LCA results with zero mass allocation of fly ash indicated that the GWP per brick ranged from 0.58 to 0.77 kg CO2 eq, with cement content and transportation being the primary contributors to emissions. The LCCA assessment demonstrated a competitive production cost of Indian Rupee5.44 (0.06$) per brick, making it financially viable for large-scale industrial manufacturing. This research provides a comprehensive framework for industries and Micro, Small, and Medium Enterprises (MSMEs) to enhance production efficiency, reduce costs, and promote sustainable manufacturing practices.