Low-carbon high-performance tunnel shotcrete series

Abstract

The invention provides a low carbon and high performance series concrete special for tunnel spraying. The concrete is prepared by mixing different mineral admixtures of different mixing amounts and adopting a low water-binder ratio, a high efficiency water reducer and an alkali-free setting accelerator. The prepared concrete has the properties of high density, good workability and durability, and can satisfy the requirements of different surrounding rock grades for the early strength of sprayed concrete. In the invention, sprayed concrete density is determined according to an environmental comprehensive level, and then a gelling material formula is selected according to a density index. Designers and constructors can select different gelling material formulas and concrete proportions according to different environmental levels and surrounding rock levels. With the characteristics of low hydration heat, high density, good workability, etc., the concrete material also has the efficacy of reducing environmental pollution, improving work environment, reducing the rebound rate, saving engineering cost and the like. Thus, the energy can be saved, carbon emission and environmental pollution are reduced, and engineering cost is substantially saved.

Description

technical field [0001] The invention relates to building materials, in particular to a sprayed concrete material specially used in primary support structures of tunnels with different environmental comprehensive grades and surrounding rock grades. Background technique [0002] At present, the vast majority of mountain tunnel structures use composite lining, and a few tunnel structures use single-layer lining. Regardless of whether composite lining or single-layer lining is used for tunnel structures, shotcrete is used as the main support method. After the tunnel is excavated, concrete is sprayed on the surrounding rock at the "fastest" speed, the purpose of which is to restrain the relaxation or deformation of the surrounding rock in the "shortest" time. In order for shotcrete to play a supporting role, it is required to reach a certain strength in a "short time", which is the early strength of shotcrete. At the same time, the shotcrete should have good adhesion so that it ...

AI Technical Summary

Problems solved by technology

[0003] There are great differences in shotcrete formulations and construction techniques around the world. Due to the complexity of the process and when the surrounding rock is not stable, the quality of the shotcrete is difficult to guarantee, and there are major safety hazards in the tunnel structure.

The use of shotcrete in tunnel structures in my country started relatively late, so there is a big gap between shotcrete technology and concrete formulations compared with some developed countries in Japan and Europe. Most of the tunnel shotcrete construction uses dry spraying technology, with large dust and more rebound , The mix ratio is difficult to control; in most cases, alkali accelerators are used, which will cause great damage to the skin of workers, and the concrete will be severely corroded under the action of groundwater; the cementitious material adopts a single P.O52.5 Portland cement and the amount of cement Large, the amount of cement used in a single concrete exceeds 500kg, which is neither economical nor environmentally friendly

Images