Physicists from the St. Petersburg State Institute of Technology have invented an unusual method for improving concrete. The researchers believe that the concrete structure will become more uniform, and concrete products will obtain unprecedented durability and water-resistance if, while hardening, concrete is exposed to the influence of electromagnetic field of a strictly determined frequency.
The actual process is as follows: the concrete blocks while they are still in the mould are placed in a kind of metal barrel, which serves as an antenna or resonator. Short pulses of alternating current pass through it. The processing time (a few seconds) and parameters of the electromagnetic field created by the current are strictly determined. As a result, concrete becomes heterogeneous, and with higher quality.
The common problem for cement, concrete and other similar building materials is heterogeneity of structure. The heat inevitably evolved in the course of reaction between sand and cement is carried off slowly and non-uniformly, that is why concrete also hardens non-uniformly. Besides, while concrete is hardening the educed gases form pores and cavities in the body of the products, the pores and cavities being of different size. This results in insufficient durability, sometimes even brittleness of concrete blocks. These drawbacks can be avoided if concrete is stirred up, but this is practically impossible to do. The trick the Technical University researchers play with concrete resembles stirring to some extent.
Olga Maksimenko | informnauka
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