Multi-objective optimization of influential factors on production process of foamed concrete using Box-Behnken approach

Foamed concrete is a type of lightweight concrete produced from cement, water, foam and sand; however, no sand is required for making low density foamed concrete. Foam is generated from mixing of water and foaming agent under high pressured air. The two most important outputs of foamed concrete production process are dry density and compressive strength in 28 days after the time of mixing which are considered as the physical-mechanical properties. Furthermore, the cost of materials is a very critical issue. The aim of this paper is to optimize the ratio of three effective factors for foamed concrete production including cement mass, water and foam volume in order to achieve minimum density and maximum compressive strength along with minimum cost. To this end, the Box-Behnken design of response surface methodology has been used for optimization purposes. 15 experimental samples were prepared and MINITAB statistical software was employed to analyze and determine the mix-design of materials in different ranges of densities based on their applications. The result reveals that Box-Behnken design leads to optimized values of foamed concrete production outputs. Finally, the optimum values of each input factors for some critical densities and their corresponding compressive strengths were obtained.