Foam Concrete - Effects of Different Types of Foaming Agents

Foam concrete has many serval advantages over conventional concrete such as minimization of structural dead load, less manpower, lower transport and operational cost and increase fire resistance, thermal insulation and sound absorption [1]. However, one of the drawbacks of this material is its high drying shrinkage. Therefore, the aim of this research was to compare the effects of two different types of foaming agents (protein and synthetic) on the foam stability, microstructure and compressive strength of foam concrete at varying densities.

The results of the present study showed that protein-based foaming agent exhibits superior performance than synthetic-based foaming agent in terms of foam stability and microstructure. It was also observed that the foaming ability of protein-based foaming agent is dependent on its pH value. It is suggested that the use of protein-based foaming agent with a pH value above 10 yields optimal results.

In addition, it was found that the foaming process is affected by the amount of water used in the mix. Using a higher quantity of water than necessary destroys the bubbles in the mixture. The optimum ratio of foaming agent to cement is 0.6 %.

During the curing process, it was observed that the foamed concrete shows a significant decrease in drying shrinkage with time. This is due to the fact that the presence of hydration products in the foam concrete promotes drying shrinkage. Furthermore, the pore structure of the protein-based foamed concrete is more uniform than the synthetic-based one.