And application of concrete expansion agent for compensating concrete dry shrinkage

Abstract

The invention relates to a concrete expansion agent and the application thereof for compensating concrete dry shrinkage. The concrete expansion agent has low wet curing requirement after slurry is formed, has proper expansion in an early period, continuous micro expansion in a later period and stable hydration products after expansion and has a better compensation function for the concrete dry shrinkage. The concrete expansion agent is light-burned MgO with a hydrated activity value of 40-90s. The concrete expansion agent has the MgO content which is larger than or equal to 85 percent and burn loss which is less than or equal to 5 percent, a concrete analysis sieve of 80 micron is used for detecting, and the residue on sieve of the concrete expansion agent is ranged from 3 percent to 10 percent. Compared with the prior product, the hydration product has low water requirement, low wet curing requirement after the slurry is formed, higher hydrated activity, quicker expansion in the early period and continuous micro expansion in the later period, and the expanded hydration product has stable performance, can not generate a retraction phenomenon and has a better compensation function for the dry shrinkage of the concrete slurry.

Description

technical field [0001] The invention relates to a concrete expansion agent, in particular to an expansion agent which has a better compensating effect on concrete drying shrinkage. Background technique [0002] There are many patents and varieties of concrete expansive agents at home and abroad. According to the main mineral components they contain, they mainly include sulfoaluminate type, aluminate type, lime type, and alunite type. The widely circulated concrete expansion agent on the market in my country is the ettringite-based sulphoaluminate expansion agent, which has many advantages in application, but also has fast hydration rate, large early expansion, and shrinkage after expansion. Unfavorable factors such as large drop, delayed ettringite reaction, large water demand, and the need to strengthen wet curing. The early expansion of the ettringite type expansion agent is too fast, which determines that this type of concrete expansion agent can only play a role under re...

AI Technical Summary

Problems solved by technology

This kind of MgO expansion agent used in hydraulic dams can only play a role in the later stage due to the high calcination temperature and low hydration activity (the hydration activity value is generally about 240s), and has a negative effect on the temperature drop and shrinkage of mass concrete. Good compensation effect, but little compensation for concrete drying shrinkage commonly found in civil buildings

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