Potential application of all-solid waste belite-ye'elimite cement in high early-strength pavement concrete: Strength formation, characterization, and benefit evaluation

To mitigate the issues of the negative environmental effects and high costs when traditional high early strength concrete is used for rapid pavement repair, this study prepared all-solid waste belite ye'elimite cement (BYC) based on bulk industrial solid waste (coal gangue, carbide slag, and desulfurized gypsum). Its application potential in high early strength pavement concrete was analysed. Mechanical property tests of BYC concrete (BYCC) showed that its initial strength increased rapidly, and the 6 h flexural strength (5.5 MPa) could meet the traffic demand of heavy load pavement. At 24 h, the flexural strength, compressive strength, and impact resistance of BYCC were better than those of traditional Portland cement concrete, with a curing age of 28 days. Through X-ray diffraction, Fourier infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and nuclear magnetic resonance analysis, the mechanism of the rapid increase of BYCC strength was determined: the early high-activity tetracalcium sulphoaluminate hydration led to the formation of needle-rod ettringite and flocculent aluminium gel and constructed high strength cement hardening slurry, which gave BYCC high mechanical properties in the early curing period. The life cycle assessment results showed that, in comparison to Portland cement, BYC can reduce the carbon emission and energy consumption of pavement over the entire construction cycle by 37 % and 7 % respectively, saving about 5 % in costs.