Super slump type polycarboxylate water reducing agent for bored pile concrete and preparation method thereof

Abstract

The invention provides a super slump type polycarboxylate water reducing agent for bored pile concrete. The water reducing agent is in a liquid state and comprises the following ingredients: sodium oleate, water reducing type polycarboxylate plasticizer, slump type polycarboxylate plasticizer, hydroxyethylidene diphosphonic acid, 2-acrylamide-2-methylpropanesulfonic acid/itaconic acid/acrylic acid terpolymer, hydroxypropyl methyl cellulose or hydroxyethyl methyl cellulose, air entraining agent and triisopropanolamine. The super slump type polycarboxylate water reducing agent for bored pile concrete provided by the invention has the following beneficial effects that by using the super slump type polycarboxylate water reducing agent, the bored pile concrete is good in homogeneity, the static bleeding rate of the bored pile concrete can be generally less than 1%, stable working performance can be maintained within a long time span, meeting the working property of concrete after 0.5-5.0h can be met by adjusting the formulation and dosage and improving the compressive strength ratio of the concrete, and the 28 d strength can be more than 130% of that of benchmark concrete. The invention further provides a preparation method of the super slump type polycarboxylate water reducing agent for bored pile concrete.

Description

technical field [0001] The invention relates to the field of concrete production, in particular to a super-slump-proof polycarboxylate water reducer for cast-in-place pile concrete and a preparation method thereof. Background technique [0002] Cast-in-situ pile projects have high requirements on the homogeneity of concrete. The pile structure of some projects is as long as 50 meters, or even as long as 100 meters. After the concrete bleeds, it may cause major problems to the project. First of all, after the concrete bleeds, a certain amount of free water will accumulate at the pile head, which will increase the water-binder ratio of the pile head concrete, resulting in a decrease in concrete strength, or even loss of strength; moreover, some pile foundation projects need to insert steel pipe column components , After the concrete bleeds, the stones sink, and it is difficult or even impossible to insert the steel pipe column. Therefore, reasonable measures must be taken to ...

AI Technical Summary

Problems solved by technology

[0006] 1. Due to the high water-reducing characteristics of polycarboxylate water-reducing agent, the prepared cast-in-place concrete has high sensitivity to water consumption, which can easily cause serious segregation and bleeding of concrete;

[0007] 2. Due to the possibility of uncertain pouring time, when the polycarboxylate plasticizer-slump-retaining component is added to meet the long-term workability requirements, the reliable dosage cannot be reasonably determined. When the transportation is smooth, the concrete is relatively stable. Perfusion in a short period of time is prone to the problem of fluidity hysteresis "returning to large"

[0009] In order to improve the homogeneity of concrete, people try to greatly increase the cementitious material or add silica fume, but this method is costly, and it is easy to increase the loss of concrete fluidity, and it cannot ensure the homogeneity and ultra-slump retention requirements of concrete

In recent years, there have been experimental reports on the application of silicon nanomaterials to cement-based concrete. It is said that the homogeneity and strength of concrete can be greatly improved, but this material will greatly accelerate the loss of concrete fluidity, so it is difficult to meet the requirements In addition, the cost of silicon nanomaterials is high and not easy to obtain

[0010] In terms of slump retention, traditional sodium gluconate, citric acid, white sugar, and commonly used phosphates are difficult to reliably meet the requirements of concrete flow performance and high homogeneity of concrete for more than 3 hours

For example: commonly used hydroxycarboxylates, such as gluconate, tartrate and other retarding and slump-retaining agents, are likely to cause concrete bleeding, and the super-slump-retaining effect is not good, and generally cannot reach 3 when the homogeneous state is satisfied. The slump-preserving effect of more than one hour; the common sugar retarder and the polycarboxylate superplasticizer are poorly compatible with concrete, resulting in sticky concrete and poor fluidity, and most of the slump-preserving effects cannot be guaranteed

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