Lightweight aggregate (LWA) has a long track record of quality and performance in construction industry. Since its development in the early nineteen hundreds, LWA produced by the rotary kiln process has been used extensively in asphalt road surfaces, concrete bridge decks, high-rise buildings, concrete precast and pre stressed elements, concrete masonry and geotechnical applications. Naturally available raw materials suitable for manufacturing lightweight mineral granules are pumice, perlite, vermiculite, expandable clay and slate. The quality of LWA results from a carefully controlled manufacturing process. In a rotary kiln, selectively mined shale, clay or slate is combusted (firing) in excess of 2000°F. The LWA material is then processed to precise gradations. The result is a high quality, lightweight aggregate that is inert, durable, tough, stable, highly insulated, and free draining. Moreover, the expanded clay production process allows nondangerous waste materials to be reclaimed and thereby avoids the necessity to dispose of them in a landfill or dump—this benefits the environment and also offers economic advantages. LWA gives designers greater flexibility in creating solutions to meet the challenges of dead load, terrain, seismic conditions, construction schedules and budgets in today’s market place.

Expanded clay shale (ECS) and light weigh expanded clay aggregate (LECA) are among the common lightweight materials that have been applied successfully in geotechnical application.

Typical properties of LECA manufactured from natural and waste materials