Macroporosity-based prediction models for mechanical properties of foamed concrete

Foamed concrete is a versatile lightweight material that has attracted considerable research attention during the last few years. Various researchers have proposed strength prediction models based on the porosity of the material. However, these models give significantly different values of strength for the same foam porosity. Although the Balshin-type power functions have been found to adequately fit the experimental data, the power exponents reported by various researchers have had wide variations, ranging from 2.7 to 4.9. A fairly similar situation prevails with regards to models for predicting the elastic modulus of foamed concrete. In this research, through an experimental study and also re-examination of previous works, a general expression is derived for quantifying the effect of foam content on the strength of foamed concrete. Using the concept of paste fraction porosity, the discrepancy between power exponents reported by various researchers was resolved. It was found that a Balshin-type function with a power exponent of 3 can be used for the prediction of the strength of foamed concretes, provided the porosity is considered as the paste fraction porosity P_f′. With regards to elastic modulus, by providing new experimental data, more insight is provided on the effect of foam porosity on this parameter.