Solid waste-based super-retarded damp-shotcrete for low carbon and environmental protection

Earth-rock waste is recycled and used to prepare damp-shotcrete to realize the resource utilization of low value-added materials. In the production of manufactured sand and manufactured stone, earth-rock waste cannot enter the production process, resulting in serious resource loss. During the preparation of damp-shotcrete, the water in the earth-rock waste will lead to cement failure. This study proposes a solid waste-based super-retarded damp-shotcrete material that improves resource utilization while achieving low-carbon environmental protection, which can delay cement hydration to 72 h. Firstly, the optimal mix ratio of solid waste based shotcrete materials and super retarders was subjected to screening test, compression test, slump test and setting time test to determine. Then, the new technology of material use is introduced, and the application process in a mine is expounded. The best mix proportion of solid waste-based super-retarded damp-shotcrete is as follows: cement: fly ash: machine-made stone: machine-made sand: earth-rock waste = 1: 0.25: 1.09: 0.44: 1.33. The best mix proportion of super retarder is as follows:sodium gluconate:sodium tripolyphosphate:A polycarboxylate superplasticizer = 1:19.69:11.8. Under the best mix proportion, the compressive strength of solid waste-based super-retarded damp-shotcrete can reach 8.19 MPa after 1 day, and the slump of fresh concrete is 210 mm. The results indicate that solid waste-based ultra-retarded damp-shotcrete material has achieved the feasibility of using earth-rock waste in shotcrete. At the same time, the cost of underground support and resource loss are effectively controlled, the utilization rate of earth-rock waste is significantly improved, and carbon emissions in raw material production are reduced.