Development of a biopolymer modified geopolymer based cementitious material for enhancement of pumpable roof support

This paper investigates the utilization of biopolymer to improve the ductility of class F fly ash based geopolymer cementitious material developed for pumpable roof support. Specifically, two biopolymers, kappa-carrageenan (CAR) and gellan gum (GEL), at different dosages, were used to prepare the geopolymer cementitious material specimens and systematic tests were performed to measure the peak uniaxial compressive strength (UCS), Young’s modulus, residual UCS, and tensile strength of the hybrid geopolymer-biopolymer cementitious material (HGBCM). The results show that incorporation of biopolymer up to 0.5 wt.% slightly increases or decreases the peak UCS and Young’s modulus, but effectively increases the maximum residual UCS at 0.3 wt.% biopolymer as required. Furthermore, the included biopolymer slightly decreases the tensile strength, with the HGBCM containing CAR showing higher tensile strength than that containing GEL. Compared with the cementitious material currently used in practice, the HGBCM developed in this study shows superior performance.