Unraveling the expansion mechanism in lightweight aggregates: Demonstrating that bloating barely requires gas

Lightweight aggregate bloating process has been studied by a simple experiment using an archetypal clay to know the actual amount of gas involved in expansion. Considering the relationship between gas loss (LOI) and volumetric changes over time, three main stages are identified: 1) a preheating stage of massive gas loss (close to 80% of the total) with hardly any volumetric change; 2) a very brief transition stage, in which sintering (shrinkage) and closed (micro)porosity formation begin, accompanied by a sudden gas loss (close to 100% of the total); 3) the bloating stage itself, in which an appropriate viscosity is reached, allowing the available residual gas (