Myth Versus Reality

Lightweight concrete has been a staple of the built environment for centuries, predating the Roman Empire. While some early lightweight concrete structures still stand, their materials bear little resemblance to today’s offerings. Industry professionals now recognize structural lightweight concrete as a strong, low-density mixture of Portland cement, water, and various combinations of normal weight aggregates and lightweight aggregates. In such concrete, lightweight aggregate produced from shale, clay, or slate is heated to approximately 2000 degrees F in a rotary kiln process. During this process, it softens and bubbles form that remain as unconnected pores when it cools.