Rapid curing prospects of geopolymer cementitious composite using frontal polymerization of methyl methacrylate monomer

Abstract

This paper investigates the prospects of thermal frontal polymerization (FP) technique for rapid curing of fly ash-based geopolymer composite (GPC). In this research, FP is used as an on-demand heat source alternative to conventional external heat application method. This method involves the mixing of an organic monomer (methyl methacrylate - MMA), crosslinker (trimethylolpropane triacrylate – TMPTA), and organic soluble initiator (Aliquat® persulfate - AQPS) with the GPC mortar (fly ash, sodium silicate, sodium hydroxide, and sand) for geopolymerization. An instantaneous application of spot heat initiates the exothermic polymerization of the organic monomer (MMA), forming a reaction front that provides heat needed for the geopolymerization activity, which ultimately produces a solid finished product by propagating through the GPC matrix. This solid finished product is termed in this article as frontally polymerized GPC (FPGPC). The polymerization of the above-mentioned organic monomer (MMA) in the FPGPC matrix was established by FTIR and Raman Spectroscopy. In addition, SEM analysis revealed a hybrid composite consisting of an interpenetrating network (IPN) of inorganic and organic components. This initial study showed that FPGPC achieved impressive compressive strength at early age (within an hour) as compared to both GPC and Ordinary Portland Cement (OPC) companion specimens. However, the strength at latter days and porosity of FPGPC did not match with that of GPC and OPC, which could be improved by optimizing the FPGPC mix and controlling the temperature rise during MMA polymerization. Hence, significant potential of FPGPC as construction material is apparent with limitations to be resolved through further research.