Lightweight Concrete Strength Reduction Factor

Since the coarse aggregate is generally the weakest component of lightweight concrete, lightweight concrete generally fails through the crushing of the coarse aggregate.

Firstmix caters for the weakening effect of the coarse lightweight aggregate by using strength reduction factors, which represent the ratio of the strength of concrete made with a particular lightweight coarse aggregate to the strength of concrete made with normal weight aggregate.

The FIP Manual of Lightweight Aggregate Concrete, References 25, provides data in Figure 3.7 for relating the values of these strength reduction factors for different residual absolute volume/cement ratios to the Critical Strength of Ligthweight Concrete.

Firstmix allows the user to define the strength characteristics of a lightweight coarse aggregate by specifying the strength reduction factor of concrete made with the aggregate for a given residual absolute volume/cement ratio on the Laboratory Measurements Dialog.

Range: 5 - 90 MPa or 7250 - 13050 psi.