A special water reducing agent for steel pipe jacking self-compacting concrete and preparation method thereof

Abstract

The invention discloses a water reducing agent special for steel pipe jacking self-compacting concrete. The water reducing agent is prepared from the following components in parts by weight: 150-300 parts of polyester type polycarboxylic acid mother solution, 100-200 parts of polyether type polycarboxylic acid mother solution, 0.2-1 part of a defoaming agent, 1-10 parts of an air entraining agent, 20-50 parts of a viscosity increaser, 100-200 parts of sodium nitrite, 50-80 parts of sodium gluconate and 160-580 parts of water, wherein the defoaming agent is a high-alcohol defoaming agent; the air entraining agent is of alkyl or alkyl aromatic sulfonic acid type; the viscosity increaser is a water-soluble polyacrylate viscosity increaser. By adopting the technical scheme of the invention, the generated beneficial effects are as follows: the 5-hour fluidity of the steel pipe concrete surely does not have loss, and before and after concrete pouring, the time for ensuring that the expansion degree reaches 500mm is within 6S; the expansion degree is more than or equal to 700mm; the time for the concrete to pass through a V-shaped funnel is within 18S; the gas content of the concrete before and after jacking is kept to be 3-5% without pumping loss; the water reducing agent has a shrinkage-reducing property to the steel pipe jacking concrete, so that the shrinkage of concrete is effectively replenished.

Description

technical field [0001] The invention relates to the technical field of concrete admixtures, in particular to a preparation method of a special polycarboxylate water reducer for steel pipe jacking self-compacting concrete. Background technique [0002] Ordinary concrete is poured from top to bottom, while jacked concrete is poured from bottom to top by reverse push extrusion jacking construction. During the jacking process of concrete in the steel pipe, due to the high pressure, the concrete is easy to Segregation bleeding occurs, concrete diverges, and the air content increases, which affects the strength. Because of the special construction of this kind of jacking concrete, there are special requirements for various raw materials of steel pipe jacking concrete. [0003] In the process of concrete pumping and jacking, external vibration is not allowed, so the pump pressure is relatively large during the pumping process. When the pump pressure in the steel pipe is high, the ...

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Problems solved by technology

[0002] Ordinary concrete is poured from top to bottom, while jacked concrete is poured from bottom to top by reverse push extrusion jacking construction. During the jacking process of concrete in the steel pipe, due to the high pressure, the concrete is easy to Segregated bleeding, concrete divergence, and increased air content affect the strength

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