A review on the stability of mineral foam in the fresh state: influencing factors

Abstract

Minerals foam with a low density has excellent thermal and acoustic insulation properties due to its highly porous structure. However, the reduction of density, can be achieved by reducing the solid phase fraction (cement paste) versus the air phase in the foam, leads to instability and collapse of foam at its fresh state. To improve the mineral foam stability during the fresh state, it is very important to better understand the mechanisms and the major factors influencing bubble stability. The progress in foamed concrete production techniques and foam destabilization phenomena (drainage, coarsening and coalescence) in the fresh state are investigated. The influence of major factors such as density, surfactants, cement paste rheology, additives (superplasticizer and accelerator), the type of cement, pozzolanic additions and the production temperature on foam stability is analysed. In general, the current approaches to provide an optimal foam stability are based on optimizing the binder mixtures, adjusting the preformed foam method to produce the material, controlling the binder rheology and curing conditions, and modifying the gas-liquid interface with selected surfactants and incorporating nanomaterials.