Evaluation of freeze-thaw resistance of geopolymer concrete incorporating GFRP waste powder

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This study investigates the use of glass fiber reinforced polymer (GFRP) waste powder as a partial replacement for cementitious materials in the synthesis of geopolymer concretes (GPCs), focusing on their durability under freeze-thaw (F-T) conditions. Two types of binary GPCs were synthesized: GFRP powder/ground granulated blast furnace slag (GGBS)-based GPC and GFRP powder/fly ash (FA)-based GPC, with a GFRP powder weight content of 30 %. Single GFRP powder-based, GGBS-based and FA-based GPCs were prepared as reference materials. The F-T resistance was evaluated through mass loss and residual compressive strength (RCS), as well as examining the microstructure using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). Results demonstrated that the mass loss of all GPC samples remained below the critical value of 5 % after 300 cycles. The incorporation of 30 wt% GFRP powder into GGBS-based GPC resulted in improved resistance to F-T damage, increasing the number of cycles endured from 200 to 300. Similarly, adding 30 wt% GFRP powder to FA-based GPC demonstrated enhanced resistance to F-T deterioration, with the number of cycles increasing from 150 to 175. The pore distributions of GFRP powder/FA-based GPC remained relatively unchanged before 200 F-T cycles, indicating it effective resistance against F-T conditions. GFRP powder/GGBS-based GPC exhibited a more uniform and denser microstructure with a reduced presence of pores, even after enduring 300 F-T cycles, making it better equipped to withstand F-T cycles. Furthermore, prediction models were developed to estimate RCS and damage evolution due to F-T conditions, producing accurate results compared to test data. This study presents an effective method for the utilization of GFRP waste as a building material in cold environments.