Feasibility of using plasticisers for producing heat insulation foam concrete

Abstract

Based on the audit findings of raw materials used in concrete manufacture, this study aimed to optimise the composition of non-autoclaved heat insulation foam concrete (grade D300). When planning an experiment, a strength characteristic of foam concrete was taken as a parameter, while the cement water factor (W/C) of the cement mortar (matrix) and the concentration of a foam solution were taken as determinant factors. The research area was chosen based on the foam concrete’s ability to form the structure and ensure its stability. The "W/C" factor was considered within the following values: 0.60 ÷ 0.84 for foam concrete without a plasticiser, 0.54 ÷ 0.78 with a plasticiser. The concentration of the work foam solution was varied across the range from 1 to 9%. Samples of heat insulation foam concrete with dimensions of 100x100x100 mm were moulded using a foam concrete mixture prepared according to the conventional technology. The compressive strength of the samples was determined by the destructive method. In the course of the work, the influence of W/C of cement mortar and the concentration of foam work solution on the strength of foam concrete with and without polycarboxylate-based plasticiser was determined. The optimal amount of water was defined and substantiated to obtain the porous structure of foam concrete with an average density of 300 kg/m³ using a synthetic foaming agent, ensuring the maximum strength. It was concluded that using a superplastici ser for the production of low-density foam concrete is impractical. The compressive strength of heat insulation foam concrete increases with increasing W/C. The following correlation was observed between the investigated factors: the change in strength in the function of W/C is less prominent at a low concentration of the foam solution. To manufacture heat insulation foam co ncrete with a density of D300 based on synthetic foaming agent and general Portland cement, the optimal W/C (including water in the foam) should amount to 0.8.