Lightweight concrete is designed to reduce the weight or dead load of a concrete structure. Lightweight concrete weights 20% – 40% less than normal-weight concrete. Mixes are proportioned using special aggregate such as expanded shale, clay or slate that is treated by being fired in a rotary kiln to develop a porous structure. Lightweight concrete allows flexibility in structural design of load bearing elements such as footings and columns. In buildings, lightweight provides a higher fire-rating and benefits from energy conservation as it provides higher R-values.
Lightweight Concrete is most commonly used for slabs on metal decks, bridge decks, parking structures and tilt-up walls.