Experimental study on fracture performance of coal gangue coarse aggregate concrete reinforced by multi-factor synergy

The resource utilization of coal gangue is in line with the concept of green development in China, but the practical engineering application of coal gangue concrete is limited due to the low strength and high water absorption of coal gangue aggregate. In order to study the effects of different aggregate strengthening methods on the damage and fracture characteristics of coal gangue concrete, four strengthening treatment methods were used to strengthen coal gangue aggregates by four strengthening methods: cement slurry wrapping method (GC), water glass immersion method (SC), cement slurry-carbonization synergistic strengthening method (GT) and cement slurry-water glass synergistic strengthening method (GS). The fracture properties of the strengthened gangue concrete were studied by using crushed stone concrete (NC) and non-reinforced coal gangue concrete (MC) as the control group, combined with digital image correlation (DIC) technology. The results show that the four strengthening methods can delay the occurrence and development of cracks and improve the fracture resistance of gangue concrete, among which the synergistic strengthening effect is the most obvious, compared with the MC group, the cracking toughness of the specimen in the GS and GT groups are increased by 9.09% and 13.64%, and the instability toughness are increased by 25.0% and 36.21%. The fracture energies increase by 12.63% and 17.94%, respectively. The GT group has the largest improvement in fracture performance, which is comparable to that of the NC group. This provides a theoretical basis for the practical engineering application of coal gangue concrete.