The influence of foams, having different expansion ratios, on the structurization of thermal insulation foam concrete

Abstract

Introduction. The article addresses the influence of foams, having different origins and expansion ratios, on the structurization of thermal insulation foam concrete. The study is focused on solving the problem of the binder hydration conditions in the interpore space of the foam concrete mixture and maintaining its stability. The goal is to design an economically effective composition. Materials and methods. To analyze the structurization process, foam concrete samples, featuring average density grades D300 and D500, were made using ordinary Portland cement. The nature of the surfactant substance of the foam, its expansion ratio and the water-cement ratio of the solution are the variable factors determining parameters of the material structure. The strength of the foam concrete was used to evaluate the cement hydration conditions. The strength was identified according to GOST 10180. Parameters of the macrostructure were measured using the Levenhuk optical microscope and the LevenhukLite software. Results. It is found that hydration in the interpore space of the mixture is implemented to the fullest extent when a protein foaming agent, featuring a low foam expansion ratio, is used. The foam concrete, thus made, has closed pores, whose diameter varies in a small range of values, while the partition thickness exceeds the maximum size of the cement grain. An increase in the foam expansion ratio and a low value of the water-cement ratio of the solution lead to the uneven distribution of air in the mixture and reduce the thickness of the interpore partition. In this case, the structure of the foam concrete is “friable”; it represents conglomerates of interconnected pores. Conclusions. Since the geometry of the macrostructure of the material has a significant influence on the heat transfer process and strength, the protein foaming agent, featuring a low foam expansion ratio, is preferable for the production of thermal insulation foam concrete using standard Portland cement without re-grinding. Otherwise, a higher foam expansion ratio foam requires an increase in the specific surface area of the binder.