Workability keeping agent for ballastless track self-compacting concrete and preparation method of workability keeping agent

Abstract

The invention belongs to the technical field of concrete admixtures, and particularly relates to a workability keeping agent for ballastless track self-compacting concrete and a preparation method ofthe workability keeping agent. The workability keeping agent is formed by performing mixing under stirring on the following materials, in parts by mass: 17-28 parts of a polycarboxylic acid super plasticizer, 0.02-0.5 part of an HLB value regulating agent, 0.01-0.05 part of a dispersion keeping auxiliary agent, 0.5-2.5 parts of a retarder, 0.02-0.5 part of an antifoaming agent and 68.9-82.45 partsof deionized water; and the preparation method of the workability keeping agent is a normal-temperature normal-pressure polymerization reaction. The workability keeping agent for the ballastless track self-compacting concrete provided by the invention can realize the purpose that the concrete has no slump loss within 3 h in a high-temperature environment of 35 DEG C and does not affect the finalsetting time of the concrete; and in addition, the preparation method is simple, has a pollution-free preparation process, low raw material costs, and wide adaptability to concrete raw materials.

Description

technical field [0001] The invention belongs to the technical field of concrete admixtures, in particular to a ballastless track self-compacting concrete workability retainer and a preparation method thereof. Background technique [0002] In recent years, my country's CRTSⅢ slab ballastless track structure with independent intellectual property rights has been widely used in high-speed railways. As its key structure, the adjustment layer under the track slab is mainly composed of self-compacting concrete. In addition to strict requirements on mechanical properties and durability, self-compacting concrete materials have very high requirements on the working performance of the mixture, which requires that the self-compacting concrete mixture must have high fluidity and high slurry bone stability It is also required to have good fluidity retention ability, generally requires no loss or little loss of self-compacting concrete fluidity within 2h to 3h, and meets the requirements ...

AI Technical Summary

Problems solved by technology

However, in actual engineering, the problem of maintaining the workability of self-compacting concrete is a difficult problem that often plagues construction, especially in high-temperature seasons, it often occurs that the workability of self-compacting concrete is maintained for less than 1 hour, which cannot meet the requirements of on-site construction at all.

Chinese patent documents CN 103641959 A, CN 105859980 A, etc. all propose to use unsaturated polyether macromonomer, acrylic acid or methacrylic acid and unsaturated esters as monomers for preparing polycarboxylic acid superplasticizers. Under the action of transfer agent, etc., a kind of problem that can effectively alleviate the loss of concrete slump is prepared, and has no negative impact on other properties of concrete, but the molecular weight range of the prepared polycarboxylate superplasticizer is not proposed; Chinese patent literature CN103011674 A proposes to prepare macromonomer mother liquor by dehydration reaction of polyetheramine, unsaturated monocarboxylic acid and its derivative monomer at 160±5°C, and then mix with methallyl polyoxyethylene ether at 60°C , unsaturated monocarboxylic acid and its derivative monomers are copolymerized and then neutralized with alkali

However, the preparation process of this product is cumbersome, the reaction temperature is high, and the production cost is high. In addition, adding it to concrete can only ensure no loss of slump in 1 hour, which cannot meet the requirement of self-compacting concrete without loss of slump in 3 hours.

Chinese patent document CN 105271893 A uses unsaturated polyether, unsaturated phosphoric acid and unsaturated carboxylate as monomers to prepare a slump-retaining water reducer with a weight-average molecular weight of 10,000 to 200,000. Molecular weight range, but too large for applicability

If the molecular weight of the superplasticizer is too large or too small, it will seriously affect the adsorption-dispersion effect of the superplasticizer on fresh cement particles, resulting in a decrease in its dispersion and dispersion retention performance.

Chinese patent document CN 102515618 A introduces a cross-linking monomer to prepare a water reducer with a network structure, but its preparation cost is high, the molecular structure is complicated and difficult to control, and it is difficult to realize industrialization. Conventional unsaturated ester monomers are used. achieve the same level of performance

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