Geopolymer materials exhibit excellent resistance to CO2 corrosion and low carbon emission characteristics, which are very suitable for cementing in CCUS/CCS wells. However, it is difficult to control its thickening time, which limits its popularization and application. The substitution of NaOH with Na2C2O4 and Ca(OH)2 to activate geopolymers was tried to investigate their influence on thickening time and strength of the geopolymer. The precursors used were fly ash sinker beads and slag (the mass ratio is 8:2). Results indicate that at 75°C, the thickening time of geopolymers activated by NaOH is difficult to extend with retarders, whereas those activated by Na2C2O4+Ca(OH)2 can be effectively extended using D-Gluconic acid sodium (D-GA) or ethylene diamine tetra methylene phosphonic acid sodium (EDTMPS). Additionally, geopolymers activated by Na2C2O4+Ca(OH)2 exhibit good strength properties, with compressive strengths of 25.3MPa for 24h and 25.6MPa for 48h at 75°C. Furthermore, geopolymer curing next to water-bearing rocks showed that geopolymer can also achieve excellent solidification when surrounded by water-bearing rocks, which is favorable for its application under the well cementing construction.
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