Sustainable Light Weight Concrete Using Crushed Light Weight Expanded Clay and Ground Granulated Blast Furnace

Conventional concrete consists of cement, fine and coarse aggregates, and has high density, which increases dead load and may endanger occupants during seismic events. Meanwhile, depletion of natural resources increases the demand and cost of fine aggregate. This study develops lightweight concrete by replacing fine aggregate with crushed lightweight expanded clay aggregate (LECA), with and without Ground Granulated Blast Furnace Slag (GGBS), to improve strength and durability while reducing reliance on natural aggregate. Fine aggregate was replaced with crushed LECA at 20%, 40%, 60%, 80%, and 100%, while GGBS was incorporated at constant replacement levels of 20%, 40%, and 60% in the respective mixes. Two mix series were prepared: crushed LECA with GGBS and crushed LECA without GGBS. Strength and durability tests were conducted for all specimens. Concrete containing crushed LECA with GGBS exhibited improved performance compared with LECA concrete without GGBS. This enhancement is attributed to the pozzolanic activity of GGBS, which reacts with calcium hydroxide to form additional calcium silicate hydrate (C–S–H) gel, producing a denser microstructure. The finer GGBS particles also improve particle packing and reduce voids. GGBS further refines the pore structure, improves the interfacial transition zone (ITZ), and enhances strength and durability.