Research on the foaming mechanism of microbial foaming agent and its application in foam concrete

This paper firstly investigates the effect of stirring and foaming of culture medium solution and microbial solution under the same incubation conditions as well as the factors affecting microbial foaming through settling distance, water secretion rate, foaming times, functional groups, and surface tension, to clarify the foaming mechanism and optimal proportion of microbial foaming agent; then the mechanical properties of foam concrete prepared by different preparation processes (direct mixing method and prefabricated foam method) are investigated using the microbial foaming agent. The results show that the foaming nature of microbial foaming agents is the result of the synergistic effect of microorganisms, nutrients in the culture medium solution, and microbial metabolites. Excellent performance foams were produced when the microbial inoculum was 10%, the incubation time was 48 h, the pH was 7, the stirring time was 30 min and the gelatin admixture was 0.4%. At the same time, the performance of the foam concrete prepared by the prefabricated foam method is better than that of the direct mixing method, with a dry density of 967 kg/m3 and a 28th-day compressive strength of 4.7 MPa, which meets the requirements of the industry standard A10 density class and has a uniform pore size distribution.