Composite liquid for increasing early strength of concrete mixed with polycarboxylate additive

Abstract

The invention relates to a compound liquid for improving the early strength of the concrete mixed with polycarboxylate additive and a preparation method thereof. The compound liquid is prepared with the following components in weight proportion: 25-40percent of water soluble sulphate, 3-6 percent of organic alkoxyl amine and the rest is water. The preparation method is: 1) water is put into a reaction vessel and heated to 40DEG C- 60DEG C, and organic alkoxyl amine is added and well stirred; 2) water soluble sulphate is added and stirred to form a homogenous solution. The preparing process of the invention is simple and easy to apply; the invention does not corrode steel, and does not affect the condensation of concrete and reduce the later strength of concrete. The addition of the compound liquid is 0.5-1.5 percent of cementing material content and can improve the compressive strength of the concrete by 30-60 percent in 16h, by 25-40percent in 1d and by 15-25 percent in 3d, and the compressive strength of the concrete does not fall in 28d, which greatly shortens maintenance period, expedites construction progress, advances turnover rate of template, shortens construction period and lowers cost.

Description

technical field [0001] The invention relates to a method for improving the strength of concrete, in particular to a method for improving the early strength of concrete mixed with polycarboxylate admixture, and belongs to the technical field of concrete admixture. Background technique [0002] Compared with traditional polycondensation-type admixtures such as naphthalene and melamine, polycarboxylate admixtures have become a worldwide research hotspot and development focus due to their low dosage, good dispersion, and large degree of freedom in molecular structure. It is called the third generation superplasticizer. According to reports, polycarboxylate admixtures in Japan have accounted for more than 80% of the total number of high-performance admixture products. Due to the rise of large-scale infrastructure such as nuclear power, water conservancy, bridges, and tunnels in China, especially the planning of the national railway passenger dedicated line network project Implem...

AI Technical Summary

Problems solved by technology

Chloride accelerators are the earliest inorganic salt accelerators, which can improve the early strength of concrete, but seriously affect the later strength of concrete, and because they contain Cl - , it is easy to cause depassivation and corrosion of steel bars, and its application is restricted

Sulfate early strength agents are likely to lead to poor performance in the later stage, and "hoarfrost" is easy to precipitate on the surface of the concrete, which affects the appearance, and increases the alkali content in the concrete, which will accelerate the alkali-aggregate reaction

Although alcohol amine accelerators have little effect on the later performance of concrete and have no chloride ions, their addition is difficult to control, which can easily cause serious retardation of concrete and decrease in concrete strength, and its high price has affected its popularity in the concrete industry. Applications

In addition U.S. Patent No. 4444593 has announced the composite type accelerator of sodium carbonate and ferric sulfate or the composition of the sodium carbonate and aluminum sulfate that Japanese patent JP6005050 announces, and its common feature is: after they are mixed into concrete, improve early strength (1 days) at the same time, that is, the strength of 28 days is reduced, so that the impermeability decreases, which is not conducive to the improvement of durability

European patent EP1547986A1 discloses an early-strength polycarboxylate admixture, but the preparation process is complicated, and it cannot solve the problem that the early strength of the commercially available polycarboxylate superplasticizers on the market is slow to develop at low temperatures

[0004] In summary, it is unsatisfactory to use traditional inorganic salt or organic alcohol amine accelerators to improve the early strength of concrete, and the high dosage will reduce the later strength of concrete.

However, the early strength effect of polycarboxylate admixtures currently on the market is not completely satisfactory, especially the strength development in low temperature environments is slow

Moreover, when traditional inorganic salts or organic early strength agents are used to compound with polycarboxylate admixtures on the market, not only is it easy to delaminate, the storage stability will deteriorate, and the dispersion performance of polycarboxylate admixtures will be reduced.

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