Polyethers ultra early and strong type concrete superplasticizer

Abstract

The invention relates to a polyether early- strength super-plasticizing agent. The preparation method comprises following steps: (1) copolymerization of water- borne free radical: 5%- 15% monomer a, 82%- 92% monomer b, 2%- 8% monomer c, and 1%- 3% monomer d copolymerizes in water- borne medium, the total amount of said monomers is 100%; (2) neutralizing reaction: adding alkoxy organic amine e showed in general formula (6) and (7) into copolymer after polymerizing reaction for neutralization, moderating the copolymer pH to be between 6.0- 7.5. The invention is characterized in that: (1) the dispersing performance and strengthening effect are outstanding at very low amount, and the strengthening effect at normal temperature or lower temperature at early stage is excellent, and the effect at middle and later stage grows stably; (2) it can reduce the concrete contract, and the contract rate is less than 90% of that of standard concrete; (3) it barely contains no chloride ion and is helpful for concrete durability increase.

Description

technical field [0001] The invention relates to a super early strength polyether concrete superplasticizer, which can significantly improve the early strength of concrete without delaying the setting time of cement, and belongs to the technical field of concrete admixtures. Background technique [0002] Compared with traditional polycondensation-type admixtures such as naphthalene and melamine, graft copolymer admixtures have become a worldwide research focus 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, Japanese graft copolymer admixtures 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 projec...

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

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 day Within) the strength at the same time, but the 28-day strength is reduced, so that the impermeability is reduced, which is not conducive to the improvement of durability

[0004] To sum up, it is unsatisfactory to use traditional inorganic salt or organic early strength agent to improve the early strength of concrete, and its dosage is high.

[0005] Reduced late strength of concrete

And the early strength effect of the new graft copolymer admixture is not completely satisfactory, especially the strength development in low temperature environment is slow

Moreover, when compounding traditional inorganic salts or organic early strength agents into high-efficiency superplasticizers, not only will stratification easily occur, storage stability will deteriorate, and the dispersion performance of superplasticizers will be reduced.

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