Mechanical Properties and Thermal Conductivity of Fly Ash-Based Geopolymer Foams with Polypropylene Fibers

This paper focuses on the effect of polypropylene (PP) fibers on the mechanical properties and thermal conductivity of fly ash-based geopolymer foams. Class C Fly ash (FA) was used as a binder material. A mixture of sodium silicate (SS) and sodium hydroxide (SH) was used as an alkaline activator of the geopolymer binder. The foams were prepared mechanically by mixing the foaming agent with distilled water at high pressure. The foams were added to the geopolymer admixture with volumes of 40% and 60%. A small dosage of PP was varied from 0%, 0.25%, and 0.50% by weight of fly ash (FA). The result showed that the strength of foamed geopolymer rises as the PP fiber content increases. The PP fiber was proven to increase the tensile strength of foamed geopolymer due to the ability of PP fiber to connect the crack and improve the tensile strength. The PP fiber amount in this study significantly affects the thermal conductivity of foamed geopolymer. However, the thermal conductivity in this study has the same properties as lightweight concrete and a little higher than gypsum board.