Method for preparing ultra-high performance concrete admixture by using concrete waste slurry

Abstract

The invention discloses a method for preparing an ultra-high performance concrete admixture by using concrete waste slurry. The method comprises the following steps: firstly, adding a surfactant into the concrete waste slurry, and dropwise adding a mixed solution of nitric acid and ferric chloride to obtain an impurity I and a solution A; adding the impurity I into a nitric acid solution, injecting a hydrofluoric acid solution, reacting for a period of time, adding a sodium hydroxide solution, and filtering out particles to obtain a solution B; dissolving a methacrylic acid copolymer in water, and dropwise adding sodium hydroxide to adjust the solution to obtain a solution C; and slowly pumping the solution A and the solution B into the solution C at the same time to obtain an admixture mixed solution D, and performing spray drying to obtain the concrete powder admixture. After the concrete waste cement paste is modified by the method, the problem that the concrete performance is reduced due to the fact that the concrete waste cement paste serves as a high-performance concrete admixture is solved, it is ensured that the early strength of the ultra-high-performance concrete is improved, and resource utilization and fine high-end utilization of the concrete waste cement paste are achieved.

Description

technical field [0001] The invention belongs to the technical field of concrete material preparation, and particularly relates to a method for preparing an ultra-high performance concrete admixture by using concrete waste slurry. Background technique [0002] In the production process of commercial concrete, a large amount of waste cement slurry will be produced, which mainly includes a large amount of waste slurry water generated after washing mixers and transport vehicles during production. The slurry contains cement, aggregates, additives, etc., which is a kind of concrete waste. At present, due to differences in technology and lack of management, as well as the lack of environmental protection awareness of production enterprises, waste cement slurry is randomly discharged and disposed of, and it takes up a lot of land for stacking and burying. Moreover, waste slurry is a strong alkaline substance, which is extremely damaging to soil. , which not only destroys the environ...

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Problems solved by technology

[0003] However, for concrete, it is mainly applied to concrete with medium and low strength grades. The method is to mix concrete waste slurry as an admixture into concrete mixing. At present, this method has been used in concrete production to a certain extent. Under the premise that the waste slurry is better treated, not only will it not affect the performance of medium and low strength concrete, but it can even improve the mechanical properties of concrete to a certain extent, but it will cause the expansion and slump of the concrete mixture to change. Small

It is studied to apply concrete waste slurry as a mineral admixture to high-strength high-performance concrete after treatment, but the main problem is that the waste slurry has a certain retarding effect, and the early strength of concrete will be reduced after mixing. Decreases the overall strength of concrete

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