Preparation of High-Ductility Cement-Calcined Coal-Gangue-Powder-Composite-Based Rapid Repair Material.

Coal gangue is a kind of solid waste. A high-ductility cement-calcined coal-gangue-powder-composite-based rapid repair material (HD-RRM) was prepared by partially replacing cement with calcined coal gangue powder (CCGP) for achieving high ductility and rapid hardening and conforming to the strength requirements of pavement layers. First, the physical and chemical properties and the reactivity of the CCGP were investigated. Second, HD-RRM material was prepared, and its tensile performance characteristic parameters were investigated. Lastly, the hydration products and microstructure of HD-RRM were characterized through tests (e.g., non-evaporable water content, scanning electron microscopy (SEM), X-ray diffraction (XRD), and comprehensive thermogravimetric analysis and differential scanning calorimetry (TG-DSC)). As indicated by the experimental results, the CCGP with a particle size of 1250 mesh exhibited the maximum potential reactivity. The optimal mixing ratio for HD-RRM in the experiments comprised a water-cement ratio of 0.27, a sand-cement ratio of 0.3, a fiber volume fraction of 2%, a cement content of 70%, a CCGP content of 20%, a fly ash (FA) content of 10%, and a superplasticizer content of 0.1%. Using the abovementioned mix design, the prepared HD-RRM was endowed with a 6 h ultimate elongation of 2.75%, an ultimate tensile strength of 7.58 MPa, a compressive strength of 45.4 MPa, and an average crack width of 125.53 μm, which meets the requirements of repair materials and provides a design method for CCGP resource utilization and asphalt concrete road and bridge deck repair.