Compound high-performance expanding agent for cement-based material

Abstract

The invention discloses a compound high-performance expanding agent for a cement-based material and belongs to the technical field of cement-based material additives. A plurality of materials such as panniculus adiposus lime, natural anhydrite, limestone, an azo compound and the like are selected as expanding components. The compound high-performance expanding agent provided by the invention is prepared by the following steps of: grinding panniculus adiposus lime, natural anhydrite and limestone according to a certain proportion to a certain fineness by a grinding machine, adding the azo compound and a dispersant in a certain proportion, and uniformly mixing. The expanding agent can be used to produce appropriate expansion of the cement-based material during plasticity and hardening phases, greatly raise dispersibility and fluidity of the prepared pulp and enhance rupture and compressive strength of the material. In addition, low alkali and microamount chlorine can raise endurance of the cement concrete construction.

Description

technical field [0001] The invention belongs to the technical field of admixtures for cement-based materials, and in particular relates to a high-performance composite expansion agent for cement-based materials. Background technique [0002] During the pouring and hardening process of cement-based materials, volume shrinkage will occur due to chemical shrinkage, cold shrinkage and dry shrinkage, and even lead to cracking of the material in severe cases. Concrete expansion agent is an admixture that can make cement-based materials produce a certain volume expansion after hydration reaction after mixing with cement and water, and is used to compensate for the shrinkage of cement concrete. For some special projects, especially for some special parts such as post-tensioned prestressed channel grouting, expansion agents must be used in the grouting materials to ensure that the material fills the gap between the embedded channels and prestressed tendons to protect the steel bars f...

AI Technical Summary

Problems solved by technology

However, studies have shown that the hydrogen molecules introduced by the aluminum powder expansion agent will cause "hydrogen embrittlement" in the steel bar, resulting in the formation of tiny cracks inside the steel bar, which will endanger the durability of the concrete structure. It has been banned from being used in the concrete structure.

Other commonly used calcium sulfoaluminate expansion agents, calcium oxide expansion agents, calcium sulfoaluminate-calcium oxide expansion agents, etc., are generally produced within 24h-14 days when they are added to cement or concrete. A certain amount of expansion can not avoid the plastic settlement shrinkage of concrete (or cement paste) in the plastic stage (within 4h), which cannot meet the requirements of prestressed tunnel grouting

At present, in the grouting construction of prestressed tunnels, quality problems often occur: the cement slurry in the tunnel is not filled, there are gaps; the cement paste shrinks after hardening and separates from the tunnel wall, etc.

[0004] The existing expansion agent products are generally made of natural mineral raw materials through high-temperature treatment, which has high cost and high energy consumption, and does not conform to the concept of "low-carbon economy" advocated by our country; Chlorine, the production process is relatively complicated

In addition, the amount of most expansive agents is mostly high, and the internal content is generally ≥10%, which has the disadvantage of poor adaptability to chemical admixtures, which leads to rapid and large loss of concrete slump, and cannot be well adapted to modern concrete construction. technical requirements

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