Mechanical and environmental performance of structural concrete with coal gangue fine aggregate

Using coal gangue sand as fine aggregate is a feasible solution for the sustainable development of construction engineering. The mechanical and environmental properties of the gangue fine aggregate concrete-filled steel tube (GFACFST) and reinforced gangue fine aggregate concrete (RGFAC) with different gangue fine aggregate replacement ratios (rGFA) were investigated experimentally and numerically. The results showed that the GFACFST and RGFAC with various rGFA showed similar failure modes. The stiffness of the stubs decreases with the increase in rGFA. The ultimate strength of the GFACFST and RGFAC decreases by 3.8 % and 12.4 % respectively when rGFA is 100 %. The ductility of GFACFST shows an ascending tendency with the increase in rGFA, resulting from the increase in the confining effect of the steel tube on the core concrete. The stress-strain constitutive model of gangue fine aggregate concrete is proposed for numerical modeling. A design method for the bearing capacity of GFACFST and RGFAC is proposed by considering various gangue fine aggregate replacement ratios of which results differ from the tested and simulated values in the range of +/- 5 % and +/- 11 %. The life cycle assessment analysis shows that the environmental impact of GFACFST is less than that of RGFAC at the same axial compressive strength. The improvement of the mechanical-environmental performance efficiency by increasing cross-section diameter is more significant than that by increasing steel ratio.