Fly ash of thermal power plant - micro fill for hydro technical concrete

Abstract

The article presents the option of using ash - fly ash of the New-Angren Thermal Power Plant (NATPP) as micro filler of a raw mix of hydraulic concrete, as the most appropriate solution to the economic and environmental problems of the Tashkent region, Republic of Uzbekistan. The total amount of utilized ash and slag waste for the 9th month of 2019 is 45,630 tons, ash disposal 2554 tons in the NATPP. These figures show that, annually, only 12-13% of ash and slag waste is used by consumers for various purposes, the remaining 87-88% of ash and slag waste accumulate in ash and slag dumps and pollute the environment of the region. The chemical composition of fly ash as a part of the raw mix of hydraulic concrete was studied, in comparison with the chemical composition of Akhangaran cement grade M400, its physical and mechanical properties were determined. We have carried out several laboratory experiments, we obtained a quantitative dependence of the effect of the ash-cement ratio on cement consumption to obtain hydraulic concrete of the required strength. According to the test results, it was found that the heat of hydration released during the setting process decreases in proportion to the ash content. This property is of great interest when concreting massive hydraulic structures in the hot season. Experiments show that when replacing part of the cement with fly ash on the first day, the set of strength slows down, and after 7 days it accelerates by 12-15%. With the use of fly ash in an amount of 40% by weight of Portland cement of grade 400, heat dissipation during hydration is reduced by almost 30-35%, which is very important for hydraulic concrete, which increases crack resistance and resistance in an aggressive environment. Summarizing the above, it can be concluded that the use of large-tonnage fly ash of the NATPP in concrete technology is a big state task, solving the priorities of the further development of the national economy and one of the strategic ways to solve the environmental problem in the NATPP zone.