CONCRETE

UDC 691.32

Alitinform №2 (71) 2023 г. 38-45 p.

Abstract

The results of studies aimed at identifying possible causes of premature failure of reinforced concrete structures and products are presented. It has been found that one of the main reasons for the destruction of concrete is chemical corrosion, due to the presence of reactive aggregates and a binder in its composition. The effect of silica content in coarse and fine aggregates and chlorine-containing components in the binder on the change in the relative strain of concrete samples is shown.
The petrographic and microscopic studies of thin sections of the test concrete samples have been carried out, which revealed the presence of alkaline corrosion, provided that the materials of the concrete components correspond to the requirements of the current GOSTs. The content of impurities in coarse and fine aggregates, even within the values allowed by regulatory documents, leads to the development of relative strain that exceed the regulatory values. Recommendations are proposed to reduce the maximum allowable total content of impurities in aggregates, under which chemical corrosion of concrete does not occur. It has been also shown that the strength of concrete at the age of 28 days and its frost resistance, determined by standard methods, are not able to reveal resistance to alkaline corrosion.

Key words:

concrete, chemical corrosion, aggregates, alkali–aggregate reaction, relative strain