THE USE OF DOLOMITE ADDITIVES IN AUTOCLAVED AERATED CONCRETE TECHNOLOGY
UDC 666.973.6/691.542
Key words: autoclaved aerated concrete, dolomite, portland cement, rheological properties, sand sludge, structure, calcium silicate hydrate, physical and mechanical properties.
For citation: Baranovskaya Ye. I., Miachai A., Volochko A. T., Husarau S. The use of dolomite additives in autoclaved aerated concrete technology. Proceedings of BSTU, issue 2, Chemical Engineering, Biotechnologies, Geoecology, 2022, no. 2 (259), pp. 94–99 (In Russian). DOI: https://doi.org/10.52065/2520-2669-2022-259-2-94-99.
Abstract
Screenings of dolomite rocks were used as a carbonate additive in autoclaved aerated concrete, which was added at the stage of grinding sandy sludge. The additive content was 10–30 wt.% of cement. The rheological properties of aerated concrete mixtures (spreadability according to Suttard, the time of swelling of the massif, the time to the set of plastic strength) were studied. It has been established that at a dosage of dolomite additive of 15–30 wt.% of cement, the swelling time of the massif is reduced from 11 min for the control composition to 7–9 min, the time to plastic strength is reduced from 130 min to 114–125 min. However, such a change in the parameters of the aerated concrete mixture is not significant and, accordingly, its composition is not required to be adjusted. The results of the study of the main physical and mechanical properties showed that at a dosage of dolomite additive of 15–25 wt.% of cement, the coefficient of constructive quality of concrete increases by 1.15–1.40 times compared to the control sample, which is explained by a change in the composition and structure of hydrosilicate hardening products in the presence of carbonates. It is shown that the adding of dolomite leads to a change in the morphology of hydrate compounds, and the microstructure of concrete is characterized by a high content of needle and fibrous crystals of calcium silicate hydrate, which contributes to the compaction and strengthening of the material of the interpore wall and will allow to obtain a material with the required physical and mechanical properties.
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