When deciding whether or not to use lightweight concrete, a buyer needs to understand that this type of material isn’t all created equal. While it may seem straightforward that concrete mixes that contain lower density aggregates will weigh less than traditional concrete, the details of how a concrete mixture is produced can affect its strength and even its durability properties.

There are a few different types of concrete that fall into this category: Structural lightweight concrete, foamed concrete, and autoclaved aerated concrete (AAC). Structural lightweight concrete has an oven-dry weight below 800 kg/m3 and replaces dense natural aggregates with a combination of lightweight aggregates and air.

The most common aggregates for this type of concrete are pumice, tuff, scoria, and cinders. Pumice is spongy volcanic lava that has a pore structure and contains isolated voids; scoria is volcanic cinder that has tube-like, interconnected void pores. Tuff and cinders are volcanic rock byproducts that have low specific gravity.

These materials are often heat treated to enhance their ability to bind to the cement in a lightweight concrete mix and improve its strength. Adding crushed waste glass can also improve the mechanical properties of lightweight concrete.

Lightweight concrete solutions like SmartRock can make a significant difference in the time and cost of construction by reducing the amount of reinforcing steel required for floor slabs, especially in high-rise buildings. However, no matter which lightweight concrete mix a contractor chooses to use, it’s important that the concrete is tested for its strength in order to ensure it meets project specifications.