Sulfate-erosion-resistant preservative for underground concrete structure

Abstract

The invention provides a sulfate-erosion-resistant preservative for an underground concrete structure. The preservative is prepared from, by mass, 40-60% of compacting components, 5-15% of reduction components, 20-30% of barium salt, 0.5-2.5% of ettringite inhibitors and 10-20% of thaumasite inhibitors, wherein the compacting components are one or more of silica fume, metakaolin and fly ash, the reduction components are composed of polydimethylsiloxane and 2-methyl-2,4-pentanediol, and the mass ratio of polydimethylsiloxane to 2-methyl-2,4-pentanediol is 1:1-3. The preservative is resistant to erosion of ettringite and thaumasite and is also easy to manufacture and low in cost.

Description

【Technical field】 [0001] The invention belongs to the technical field of concrete admixture materials, and in particular relates to a corrosion-resistant sulfate corrosion-resistant agent for underground concrete structures. 【Background technique】 [0002] When concrete is located in soil and groundwater where sulfates are dissolved, it will be attacked by sulfates. The sulfate attack of concrete is a very complex process, generally there are four types: ettringite type, gypsum type, salt crystal type and molarite type, usually several types of erosion will coexist. For projects such as subways, tunnels, and underground pile foundations of buildings, the concrete structures are located under the surface. A large number of engineering examples show that the erosion damage types of such concrete structures are mainly ettringite type and sulphurite type. [0003] The ettringite is a kind of expansive substance. In the early stage of sulfate attack, the strength of the concrete...

AI Technical Summary

Problems solved by technology

[0003] The ettringite is a kind of expansive substance. In the early stage of sulfate attack, the strength of the concrete is enhanced because the ettringite fills the voids of the concrete structure, but with the continuous increase of the ettringite, the internal cracking and damage of the concrete are caused. , the strength of concrete decreases

Different from ettringite-type sulfate attack, molarite-type sulfate attack mainly targets the cementitious substance C-S-H gel in cement-based materials and transforms it into a non-gelling sludge-like substance, aggregate Gradually fall off from the surface to the inside, resulting in serious performance degradation

[0004] In order to inhibit sulfate erosion, practitioners in the field have developed various inhibitors or preservatives, such as: the invention patent CN102351456A published on February 15, 2012 "a kind of molarite-type sulfate erosion inhibitor and its preparation "Methods and Applications" discloses a TSA inhibitor, the main components of which are barium salt, cement clinker, admixture, zeolite and powdery water reducing agent, which has multi-stage long-term slow-release characteristics of barium ions, and can improve cement quality for a long time. The corrosion resistance of carbon-sulfur-silicate-calcium-based materials can improve the workability, strength and durability of cement-based materials, but the main function of this inhibitor is to improve the resistance of cement-based materials to carbon-sulfur-silicon-calcium-type sulfate erosion. The destructive performance is not ideal for the erosion of ettringite; the invention patent CN103641355A "selective crystallization inhibitor for sulfate corrosion resistance of concrete and its preparation method" published on March 19, 2014 discloses a selective crystallization inhibitor The molecular structure of the inhibitor has carboxylic acid groups, methyl group groups, and sulfonic acid groups at the same time, and contains iron-aluminum double-salt phases, which can significantly improve the sulfate corrosion resistance of cement concrete and reduce the sulfate corrosion resistance of concrete. There are risks of surface cracking, spalling, and strength decline in the environment, but the inhibitor is mainly to eliminate the expansion and damage of ettringite and salt crystal expansion after sulfate corrosion, and has no preventive effect on the erosion damage of carbon-sulfur-wollastonite type

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