Special multi-phosphono-containing admixture for medium/low-slump concrete and preparation method thereof

Abstract

The invention discloses a special admixture for medium / low-slump concrete. The special admixture for medium / low-slump concrete is a multi-branched-chain three-dimensional-structure low-molecular-weight compound, wherein the molecule central core is provided with 3-8 alkoxy groups, and each alkoxy group is connected with an adsorption functional group through a molecule connecting arm; the molecule connecting arms and adsorption functional groups are branched chains; each molecule connecting arm is in a polyoxyalkylene ether structure; the number of the branched chains is 3-8; and each adsorption functional group is a multiphosphate or multi-phosphorous acid. The raw materials of the special admixture for medium / low-slump concrete are easy to purchase, and the technique is simple and feasible; and thus, the special admixture for medium / low-slump concrete smoothly satisfies the demand of long slump retaining time (6 hours or above) for concrete under harsh conditions (such as high temperature, super-long-distance super-long-time transportation and the like), has low sensitivity to cement, sandstone aggregate and water consumption, has high sulfate and clay interference resistance, effectively enhances the early strength of the concrete, can implement long slump retaining time of medium / low-slump concrete, and improves the workability.

Description

technical field [0001] The invention relates to the technical field of concrete admixtures in building materials, in particular to a special polyphosphate-based admixture for medium and low slump concrete and a preparation method thereof. Background technique [0002] Today's infrastructure construction in my country has entered a stage of rapid development. The construction of high-speed railways, highways, hydropower, nuclear power, large bridges and other projects has brought new opportunities for the development of high-performance concrete. The development of the construction industry and the rise of labor costs have made ready-mixed concrete account for an increasing proportion of concrete construction. However, the increasing shortage of high-quality sand and gravel aggregates, the use of a large amount of mud-containing aggregates, and the use of a large number of mineral admixtures make the cement composition more complex, resulting in excessive loss of concrete flu...

AI Technical Summary

Problems solved by technology

These slump protection methods can only partially meet the short-term slump requirements of ordinary concrete, and it is difficult to meet the long-term slump protection requirements of high temperature and long-distance transportation of some special engineering concrete

[0011] The traditional water reducer has good initial dispersibility, but poor dispersion retention ability, while the new slump retaining agent has poor initial dispersibility, and the later growth rate is large, showing a trend of "increase first and then decrease", which is easy to cause concrete segregation Bleeding, and the slump retention time is not long enough, even if it is used in combination, it is difficult to meet the long-term slump retention requirements of high-temperature and long-distance transportation concrete, thus giving some special projects such as the Hong Kong-Zhuhai-Macao Bridge and the concrete in high-temperature areas such as Xinjiang Difficulty with application

[0012] To sum up, the method of changing the concrete mixing process to improve the fluidity of concrete is not only costly, but also unsatisfactory; the traditional compound retarder technology has a certain effect, but the effect of continuing to increase the coagulant retarder is general , It will also affect the early strength of concrete; the granulation method of water reducing agent will increase the cost, and the technical difficulty is relatively large; and although the new type of slump-preserving admixture can meet the needs of ordinary concrete, it is difficult to meet the requirements of high temperature and long distance conditions. The demand for long-term slump protection (more than 4h) of concrete

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