Retarding superplasticizer composition for roller compacted concrete

Abstract

The invention relates to a retarding superplasticizer composition for roller compacted concrete, which is prepared from 40-80 percent of barium-containing naphthalene based superplasticizer, 10-30 percent of modified lignosulfonate, 3-7 percent of plastic retaining agent, 5-15 percent of composite retarder, 1-7 percent of layer silicate mineral material, 0.1-0.5 percent of polysiloxane and 0.1-0.2 percent of air entraining agent. The retarding superplasticizer composition does not contain alkali harmful to alkali-aggregate reaction, has a better inhibition effect to the alkali-aggregate reaction, and has the advantages of high water reducing rate, strong VC value retaining capacity, good water retaining property, small bleeding rate, remarkable retarding effect and the like, so that the prepared roller compacted concrete mixture has the characteristics of good workability, small VC value loss, small bleeding rate, long setting time, greatly reduced early hydration heat and delayed occurrence time of a hydration heat peak, so as to have better construction property, mechanical property and durability.

Description

technical field [0001] The invention relates to the field of engineering materials, in particular to a retarding high-efficiency water reducer composition used for dam roller compacted concrete with the function of inhibiting alkali-aggregate reaction. Background technique [0002] my country is the country with the most dams in the world. As an advanced dam-building technology, RCC technology has developed rapidly in our country. Roller compacted concrete is ultra-dry hard concrete compacted by vibrating rollers. It is significantly different from ordinary concrete and has the following main technical features: ① The technical requirements of the cement used in terms of mineral composition, specific surface area, heat of hydration, etc. and ordinary silicic acid Salt cement is significantly different; ②The amount of low cementitious materials, a large amount of admixtures are used, and the amount of fly ash is generally more than 50%, and the early strength of concrete is...

AI Technical Summary

Problems solved by technology

The electric power industry standard DL / T 5100-1999 "Technical Regulations for Hydraulic Concrete Admixtures" stipulates the technical indicators of retarded high-efficiency superplasticizers used in hydraulic concrete, and the setting time difference between initial setting and final setting is specified as + 120 min~+240min, the setting time difference is small, it is difficult to meet the setting time requirements of roller compacted concrete construction in high temperature seasons in actual construction, so other measures must be taken to solve the problem

At present, most of the ordinary retarded high-efficiency superplasticizers are still used in the construction process of roller compacted concrete, and ordinary retarded high-efficiency superplasticizers have the following technical deficiencies: ① There is no function of inhibiting the alkali-aggregate reaction, and ordinary Naphthalene-based high-efficiency water reducer is the main component, and the alkali content is high, generally 15% to 20%. If the dam uses potential alkali-active aggregates, there will be a risk of intensifying the alkali-aggregate reaction; ②The prepared roller compacted concrete Poor workability, poor rollability, poor water retention, and bleeding during rolling construction; ③The retarding effect is not ideal, and the setting time is short, especially in high temperature seasons. This technical problem is more prominent, which cannot meet the requirements of construction. Requirements, for example: when using diabase aggregate in the RCC dam of Baise Water Conservancy Project, when the content of ordinary retarding high-efficiency superplasticizer is 0.8%, the setting time is seriously short at a temperature of 25°C; ④The raw materials are suitable for The VC value of the prepared concrete loses quickly; ⑤The ability to inhibit the early hydration of cement is poor, the early hydration heat is high, and the hydration heat peak appears early

[0005] Patent document CN1887775A discloses a "retarding high-efficiency superplasticizer for concrete", and the naphthalenesulfonate high-efficiency superplasticizer, sodium gluconate, and sodium tripolyphosphate in the raw materials used in it all contain relatively high alkali content. It is unfavorable to prevent alkali-aggregate reaction. The invention patent also uses sulfamate high-efficiency water reducer, which will easily lead to poor concrete workability and increased bleeding rate. The retarded high-efficiency water reducer disclosed in the patent literature of this invention The agent has no technical characteristics specifically for roller compacted concrete, and cannot guarantee that the roller compacted concrete has the necessary VC value retention ability, significant retarding effect and excellent water retention capacity, so it is not suitable for roller compacted concrete