Ash content for optimum strength of foamed concrete

A study has been undertaken into the properties of foamed concrete in which large volumes of cement (up to 75 wt.%) have been replaced with both classified and unclassified fly ash. This fourth paper in the series examines the effects of increasing the levels of ash on the compressive strength of the concrete. Twenty-seven different mixtures were cast with varying ash contents and densities, and the results used to develop models that have been used to predict the compressive strength of the foamed concrete. The output from the models predicts an optimum ash content for maximum strength at a given porosity and age and shows that the optimum value increases with increasing age.