The Effect of Silicate Modulus on the Properties of Polypropylene Fiber-reinforced Geopolymer Composite Material

Abstract

This study investigated the effect of the silicate moduli on the properties of the geopolymer materials consisting of Class F fly ash (FA) and ground granulated blast furnace slag (GGBFS). For this purpose, geopolymer materials were prepared with alkaline solutions composed of 10 M NaOH and sodium silicate solutions (SSs) with two different silicate moduli (2Ms and 3Ms). The geopolymer mixtures were placed in molds (40 x 40 x 160 mm) and cured at 90 °C for 5 hours. After heat curing, physical, mechanical, XRD, and SEM-EDS analyses were performed on 7-day samples. According to the findings, polypropylene fiber reinforcement improved the flexural and compressive strength of the samples with high GGBFS content. Also, according to SEM-EDS analysis, it was concluded that the higher the CaO content, the lower the compressive strength, and the higher the Al₂O₃ content, the higher the compressive strength. As a result, the 2Ms SS improved the compressive strength of the samples with higher FA content, while the 3Ms SS improved the compressive strength of the samples with more GGBFS than FA. 1.5% polypropylene fiber-reinforced 3Ms SS samples with 25% FA had the highest compressive strength.