Enhancing sustainability and mechanical performance of lime based concrete using volcanic pumice powder ash

The incorporation of novel materials and advanced technologies in the construction sector is of paramount importance for achieving sustainable and resilient infrastructure. This research centers on the creation and assessment of lime concrete altered with volcanic pumice powder ash (VPPA) as a prospective environmentally friendly building material. The target of this study is to explore the mechanical attributes and embodied carbon of lime concrete modified with VPPA, and to evaluate its efficacy in terms of eco-strength, which is 28-day compressive strength per unit embodied carbon. The study addresses the research gap regarding the limited understanding of the impact of VPPA content on the mechanical behaviour and ecological footprint of lime concrete. Response Surface Methodology (RSM) was utilized to model and optimize the VPPA-modified mixtures, enabling precise prediction of mechanical performance and environmental efficiency across varying replacement levels. The findings demonstrate that the mechanical properties, including compressive strength (CS), flexural strength (FS), splitting tensile strength (STS), and modulus of elasticity (MOE), vary with VPPA content and attain maximum values at an optimum replacement level of 9%. At this level, CS improved by 3.17%, FS by 4.07%, STS by 3.30%, and MOE by 1.63%, highlighting the significant enhancement in structural performance. Beyond this optimum level, a gradual decline in strength was observed, indicating that excessive VPPA may dilute the cementitious matrix and reduce load-bearing capacity. Furthermore, VPPA exhibits a lower embodied carbon (0.334 kg CO2/kg) compared to lime (0.73 kg CO2/kg), and the 9% VPPA replacement resulted in a 4.87% reduction in the carbon contribution. The use of VPPA offers practical benefits, including decreased carbon footprint, reduced dependence on conventional binders, and enhanced resource efficiency. These results underscore the potential of VPPA-modified lime concrete as a sustainable and high-performance alternative for diverse construction applications, supporting low-carbon infrastructure development while maintaining mechanical integrity and durability.