Masonry materials account for a considerable share of resource consumption and greenhouse gas emissions in the construction industry. In India, burnt clay bricks have traditionally been the preferred walling unit, but their production relies on wood-fired kilns and large-scale clay excavation, both of which carry significant environmental consequences. Autoclaved Aerated Concrete (AAC) blocks and Compressed Stabilized Fly Ash Blocks (CSFB) have been proposed as more sustainable alternatives because they incorporate industrial by-products and do not require kiln firing. However, a direct, field-data-based comparison of these three materials under Indian manufacturing conditions has been limited in the literature. This study presents a comparative Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) of burnt clay bricks, AAC blocks, and CSFB blocks, adopting a cradle-to-gate system boundary and a functional unit of 1 m³ of masonry material. Primary inventory data were collected through industrial site visits to three manufacturing units in Karnataka, India. Environmental impacts were quantified using openLCA 2.6.0 with the IPCC 2013 GWP 100a impact assessment method. Physical properties of the materials were tested in accordance with relevant Bureau of Indian Standards (BIS) specifications. The results show that burnt clay bricks carry the highest global warming potential at 355.04 kg CO₂ eq/m³, driven almost entirely by wood combustion during kiln firing. CSFB blocks recorded the lowest at 100.08 kg CO₂ eq/m³, while AAC blocks fell in between at 125.86 kg CO₂ eq/m³. On the cost side, burnt clay bricks were the most affordable at ₹5,176.50/m³, while CSFB blocks were the most expensive at ₹6,750.54/m³. AAC blocks offered the most balanced performance across both environmental and economic dimensions. The findings provide quantitative, locally grounded evidence to support better material selection decisions in sustainable construction.

This study carried out a field-data-based comparative LCA and LCC of burnt clay bricks, AAC blocks, and CSFB blocks under real manufacturing conditions in Karnataka, India. The findings lead to several clear conclusions. Burnt clay bricks carry by far the highest environmental burden of the three materials, with a GWP of 355.04 kg CO₂ eq/m³ that is almost entirely explained by wood combustion in the kiln. This single process accounts for 98 % of the total impact, which means that transitioning to cleaner fuels or adopting energy-efficient kiln technologies would produce the largest environmental benefit for this material. CSFB blocks demonstrated that commercially viable masonry production without any heat input is feasible, and the results confirm their environmental advantage. Their higher cost relative to clay bricks remains a practical barrier, but it is not permanent. Reducing cement content through supplementary binders, better local market development, or policy support for industrial waste utilization could all help close this gap over time. AAC blocks sit in a position that is often underappreciated: not the cheapest material, and not the cleanest, but reasonably competitive on both fronts. Their high transportation demand — largely a consequence of sourcing lime from Rajasthan — is the most actionable improvement opportunity. Securing regional lime supply alone would meaningfully reduce AAC’s transport-related footprint without requiring any change in the product. Across all three materials, cement emerged as the dominant environmental contributor in the two alternatives. Reducing or partially replacing clinker-based cement — through fly ash cement, slag cement, or other supplementary materials — is the most broadly applicable strategy for improving the sustainability of both AAC and CSFB blocks. The study also confirms a recurring challenge in sustainable construction: the material with the best environmental performance is not always the most affordable under current market conditions. Narrowing that gap will require a combination of technical innovation, supply chain improvement, and policy measures that more accurately reflect the environmental cost of conventional masonry production.

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