A practical sustainability index for comparing cementitious materials

Sustainability in cementitious materials is often assessed primarily through reductions in embodied carbon, with limited consideration of mechanical performance, durability, and economic feasibility. While lowering cement content can reduce initial environmental impact, materials that compromise structural capacity, service life, or cost efficiency cannot be considered sustainable in practical engineering applications. A more comprehensive and quantitative definition is therefore required. This paper proposes a practical framework for defining sustainable cementitious materials based on four governing parameters: strength, durability, embodied carbon, and cost. These parameters are expressed in normalized form relative to a reference system and combined into a dimensionless sustainability index that represents the ratio of material benefit to environmental and economic burden. This framework allows direct comparison of cementitious systems with different compositions and performance characteristics. This proposed approach also provides a quantitative basis for defining and comparing sustainable cementitious materials and supports performance-based assessment in both research and practice.