Preparation and properties of lightweight geopolymer by bio-based foaming agents

Lightweight geopolymer has the advantages of wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, which is expected to replace traditional building insulation materials. In this paper, green bio-based foaming agents with small 1h settlement distance, high average foaming multiple and low bleeding ratio were obtained by Cetyltrimethylammonium Bromide/yeast solution. When the amount of Cetyltrimethylammonium Bromide is 0.50 wt %, the foams prepared by the yeast and Cetyltrimethylammonium Bromide composite system exhibit the improved 1h settlement distances, the large average foaming multiple, the small bleeding ratio and uniform size. Subsequently, lightweight geopolymer was successfully prepared by the bio-based foaming agents, and the effects of different foam contents on the properties of geopolymer such as dry density, water absorption, thermal conductivity, compressive strength, and morphology were studied. With the increase of foam content, the dry density, thermal conductivity and compressive strength of the geopolymer gradually decrease, the water absorption increases, regardless of whether to add silica fume or fly ash. Herein, it is confirmed that the foaming agent based on yeast can be effectively used to prepare lightweight geopolymers, which can provide vast opportunities to turn into candidates for the novel inorganic thermal insulation material.