Synergistic effect of surfactants in porous geopolymer: Tailoring pore size and pore connectivity

With the growing interest in foamed geopolymer manufacture, there is an increasing demand for tailoring these composites’ pore structure. The binary system of two surfactants offers a possibility for enhancing foam formation efficiency and stability in geopolymer paste, however, their effects are not well understood. The influence of binary system blends on pore formation, size, and distribution in fly ash-based geopolymer matrix is investigated and their synergistic effects are evaluated. The results show that combining a nonionic surfactant with anionic Sodium Dodecyl Sulfate (SDS) increases open porosity, whereas cationic Cetyltrimethylammonium Bromide (CTAB) promotes the development of closed pores, improving thermal insulating, hygrothermal and mechanical performance. Moreover, this paper proposes a mechanism to describe the creation of pores in the presence of mixed micelles, as well as the benefit of employing mixed surfactant systems in customizing porous composites.