Ceramsite dual-doped shotcrete for high-temperature tunnel rock surfaces

Abstract

The invention discloses ceramsite dual-doped shotcrete for high-temperature tunnel rock surfaces. The concrete comprises, by cubic meter, 485-500kg of cementing materials, 450-465kg of ceramsite and 0.9kg of polypropylene fibers, wherein the cementing materials include 65-75% of cement, 15-20% of coal ash and 10-15% of slag powder. Accelerator is added by 3-5% of the weight of the cementing materials in concrete preparation, and the ratio of the water to the cementing materials is not larger than 0.5. The shotcrete has the thermal conductivity lower than that of normal shotcrete by 65-70% under the synergistic effect of the materials of a certain proportion, and the modulus of elasticity of the shotcrete is 32-40% lower than that of normal shotcrete with similar compressive strength to the shotcrete. In addition, the polypropylene fibers of a certain quality are doped in the ceramsite concrete to form a three-dimensional network structure, lightweight aggregate is prevented from floating upward while strength and toughness are enhanced, viscosity of the ceramsite concrete is increased, layering segregation of the concrete is reduced, concrete materials can be distributed more uniformly, stability of the ceramsite concrete is further improved, and the ceramsite dual-doped shotcrete is especially suitable for construction of heat-damaged tunnels.

Description

Technical field [0001] The technology of the invention belongs to the field of concrete, and in particular relates to ceramsite double-mixed fiber sprayed concrete applied to high-temperature rock surfaces of tunnels. Background technique [0002] Ordinary shotcrete is mainly composed of cement, ordinary sandstone and quick-setting agent. In heat-damaged tunnels, the rock surface temperature can reach above 50°C. Structural variation, internal factors of raw materials, etc. may cause the physical and mechanical properties of concrete itself and the bonding performance with rock to decline: [0003] 1. Due to the large amount of cement used in ordinary shotcrete, under the condition of accelerated dehydration at high temperature, the hydration of cement is insufficient, the bonding strength between concrete and rock surface is reduced, and the consolidation effect of shotcrete and rock surface is poor; [0004] 2. Since the hydration of cement itself is an exothermic reactio...

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Problems solved by technology

[0003] 1. Due to the large amount of cement used in ordinary shotcrete, under the condition of accelerated dehydration at high temperature, the hydration of cement is insufficient, the bonding strength between concrete and rock surface is reduced, and the consolidation effect of shotcrete and rock surface is poor;

[0004] 2. Since the hydration of cement itself is an exothermic reaction, heat loss is hindered in a hot environment, and the internal temperature of the concrete may rise to a higher range, forming a high-temperature early curing effect. The surface of the cement particles quickly forms a dense hydration product shell, and the early concrete The compressive strength is improved, but the shell prevents moisture from entering the cement core, so that the degree of hydration in the later stage is reduced and the strength is reduced;

[0005] 3. Due to the different thermal properties of cement and other cementing materials and coarse and fine aggregates in the composition of ordinary shotcrete, the original defects of the interface will produce local micro-stress concentration when deformed at uneven temperature, resulting in the expansion of defects and the decrease of strength;

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