Engineers have developed a concrete mixture with nano-additives that can be poured in humid climates and at temperatures down to -5 °C without compromising the quality of monolithic structures.
Construction work using concrete at low temperatures connected with various problems, since in the cold the fluidity of water in the mixture is disturbed, due to which the concrete sets worse and lumps form inside the slabs. Therefore, filling at an air temperature below 5 °C requires additional measures to prevent premature curing.
A team of scientists from the Far Eastern Federal University and the Peoples’ Friendship University of Russia proposed to introduce a special nano-modified additive into concrete, which increases the strength and durability of concrete structures erected in winter without increasing the cost of the construction process.
The complex additive consists of four components: a superplasticizer based on sulfo-naphthalene-formaldehyde, amorphous nanosilica, saponified wood resin and an antifreeze inhibitor. Such a mixture sets quickly, and the concrete has a dense structure without internal lumps. In addition, the pores in it are smaller than in ordinary ones, so moisture is not able to penetrate inside..
With the correct proportions, the mixture meets civil engineering standards and can be used in the construction of structures up to 10 stories high in humid climates. The properties of such concrete remain unchanged for 50 years..
The new mixture has already been successfully tested in the construction of a five-story car park. Concrete hardened within 28 days in natural conditions with a temperature difference of 5 °C to -6 °C, and met all the required standards.
We also previously reported on the development of self-cleaning concrete.
text: Ilya Bauer, photo: electrostal
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