Concrete reducing agent

Abstract

Shrinkage reducing agent for concrete has weight percent of 0-50% of polyvinyl alcohol, 0-60% of fatty group glycol ether, 0-50% of hydroxide alkylamine. Polyvinyl alcohol compound structural formula is -(CH2CHOH)n-,n=1700-2200, fatty group glycol ether structural formula is RO(CH2CH2O)nH, R=C1-20, n=1-10; oxidized alkyamine structural formula is R1-NH-R2OH, R1 and R2 are the alkyls of C1-20. The shrinkage reducing agent can reduce the shrinkage of cement, sand pulp and cement paste; and has the same function to dry shrinkage and self-shrinkage, can be used to Portland cement, popular cement, allblended cement and special cement. The compound is simple, and performance is stable. It can be used in many fields. It is not limited by the environment and the cost is low. It has shrinkage to different pH value, temperature and humidity.

Description

Technical field: [0001] The invention relates to a concrete additive, in particular to a concrete shrinkage reducer. Background technique: [0002] We know that the early cracking of concrete (cement + sand + gravel + water + admixture) is the most common quality accident in concrete engineering, and the reason for cracking is ultimately the shrinkage of concrete. The different mechanisms of shrinkage can be divided into drying shrinkage and autogenous shrinkage. Drying shrinkage refers to the shrinkage caused by the loss of water in the concrete to the air; autogenous shrinkage refers to the shrinkage caused by the self-drying of the interior of the concrete caused by the consumption of water in the concrete by hydration reactions. Common to the different types of shrinkage is a reduction in internal moisture content. When part or all of the shrinking deformation is restrained, the stress of drawing must be produced inside the concrete. When the instantaneous tensile str...

AI Technical Summary

Problems solved by technology

So far it has been found that several types of substances can reduce the shrinkage of concrete, such as alcohols, commonly used include diols, triols and their homologues, but these substances have a low boiling point, are volatile, and have a pungent odor and ignition point. It is very inconvenient to use in engineering practice; and alcohol polymers with larger molecular weight are convenient to use, but to achieve the required shrinkage reduction effect, a large amount of concrete needs to be mixed, which virtually increases the concrete. Cost; another class of substances that can be used as shrinkage reducing agents are ethers, such as glycol ethers, polyethylene glycol ethers, polyethylene glycol alkyl ethers, etc. These substances are better than alcohols in shrinkage reduction effects, but Most ethers are volatile and have a pungent odor, which is also very harmful to the health of operators; another shrinkage-reducing substance that has been recorded in the data is alkanolamine, such as α, β-alkanolamine, which are effective in reducing the amount of concrete mortar and cement. The shrinkage of the net paddle is very effective, but the price is very expensive, which greatly increases the cost of concrete, and it is difficult to promote in engineering