Research on the Axial Compressive Properties of CFRP - Coal Gangue Sand Concrete Composite Materials

To investigate the axial compressive behavior of the carbon fiber reinforced polymer (CFRP)-coal gangue sand concrete (GSC) composite material, the monotonic axial compression test was conducted on 24 cylindrical CFRP-GSC specimens. The effects of the replacement ratio of the gangue sand (r_GS) and the number of CFRP layers (p) on the failure mode, ultimate bearing capacity, peak displacement, load-strain relationship, and hoop strain distribution of the CFRP-GSC were analyzed. The results show that r_GS has a minor influence on the failure mode of the CFRP-GSC, which consistently exhibits explosive failure. As r_GS increases, the ultimate bearing capacity and peak displacement of the CFRP-GSC specimens decrease. When r_GS is 100%, the ultimate bearing capacity and peak displacement decrease by 8.4% and 8.9%, respectively. For the CFRP-GSC specimens with r_GS=100%, both the ultimate bearing capacity and peak displacement increase with the increase of p. As r_GS increases, the longitudinal peak strain of the CFRP-GSC specimens slightly increases. A greater number of CFRP layers provides better hoop confinement for the CFRP-GSC specimens. The utilization ratio of the CFRP is not proportional to p, and the highest utilization ratio occurs when p = 1. Finally, a prediction formula for the ultimate bearing capacity of the CFRP-GSC is proposed, and an axial compressive stress-strain constitutive model for the CFRP-GSC is established, which provided a theoretical basis for the application of this type of material in construction engineering.