Predictive modelling of sustainable lightweight foamed concrete using machine learning novel approach

Abstract

Foamed concrete is a versatile material that can be used in different construction applications and with proper mix designing, it can also be used as a structural member. The production of sustainable lightweight foamed concrete (LWFC) requires a proper mix design relation to achieve the desired physical and mechanical properties. There are a few standards such as ACI 211.2 that give mix design procedures, but the provided methods cannot be applied for all forms of lightweight concrete, particularly for LWFC. This study aimed to develop a relationship between the mix design parameters, density, and compressive strength using gene expression programming. For the development of models, an extensive database of 191 data points was collected from the published literature that comprised of cement content, sand content, water to cement ratio, foam volume as input parameters, and the dry density and 28 days compressive strength as an output parameter. The developed models were evaluated by using a regression tool i.e. coefficient of determination (R2) along with the root mean square error, mean absolute error, root square error, objective function and performance index. A strong correlation of R2 0.95, was obtained for both the density and strength models along with the least statistical errors. From the results, it has been observed that 95% of the predicted results have error values less than 2% for the density model and 91% of the predicted results have error values less than 5 MPa for the strength model. The validity of the models was further verified by conducting an experimental investigation where a satisfactory relation of R2 0.79 and 0.94 was observed for density and compressive strength models, respectively. In addition, the sensitivity and parametric analysis were also performed to analyze the influence of individual input parameters in relation to the output. The developed GEP models are expressed in the form of empirical relations that can be used for the practical application of foamed concrete in different construction applications.