Can CLC Concrete Be Used for Slab Casting?

Lightweight Concrete

• Lightweight concrete is suited for application when reducing the weight of construction members is desirable. Lightweight concrete also has insulating properties. Structural lightweight concrete is a cement-based mortar mixed with lightweight aggregates to produce a concrete weighing between 90 and 115 lbs. per square foot, compared with conventional concrete weight of 140 to 150 lbs. per square foot. Lightweight concrete doesn't have the compressive strength -- resistance to forces pressing on it -- that conventional or structural concrete has.

Cellular Lightweight Concrete

• Cellular lightweight concrete (CLC) is nonstructural -- that means it can't support the weight of part of the structure it's a part of. Cellular lightweight concrete is mixed with foaming agents that distribute minute air cells evenly through the mix so that up to 80 percent of the volume of the concrete is air, where the air content of (noncellular) lightweight concrete is around 20 percent. Both structural and cellular lightweight concrete have strong resistance to fire, but CLC is virtually noncombustible. It's used for floor and roof deck fill and insulation, applications in which structural strength isn't required.

Compressive Strength

• The specified compressive strength for concrete mix for slabs is typically 2,500 lbs.per square inch (psi). The weight of CLC ranges from 15 to 90 lbs. per square foot and even as low as 12 lbs. per square foot -- so light that it has the strength only to retain its shape while it's being placed. Design mixes for cellular concrete call for compressive strength from 100 to 200 psi typically and sometimes 500 psi.

Cellular Lightweight Concrete and Slabs

• The compressive strength of CLC can be controlled by varying the amount of air in the concrete; high strengths can be achieved. But the characteristics of CLC are suited best for different, nonstructural applications where its insulating properties, fire resistance and light weight are desirable. Meanwhile, structural lightweight concrete can meet the compressive strength required for slabs while reducing the load and providing insulation value. Choose the concrete mix that meets the performance objective for the construction project.