امکانات تولید بتن سبک با قدرت بالا از جنس خاکستر هوابرد متراکم شده Possibilities of lightweight high strength concrete production from sintered fly ash aggregate

1. Introduction Electricity produced via the burning of solid fuels is currently still one of the main sources of energy. However, this energy is not the only product created in power plants. During the process of electricity production, secondary energy products are created which are often of high quality and can be considered to be alternative resources. With regard to the large quantities of such materials that are produced, efforts have been made to search for potential ways of using them. At present, they are mostly utilised in the form of building materials. One of the suitable ways of exploiting their potential is their direct use in the form of an admixture or artificial aggregate for the production of concrete. [1, 2, 3] In the Czech Republic in the 1980s, an artificial aggregate (Agloporit) was manufactured via self-firing at a highcapacity plant in Dětmarovice near Ostrava with the help of Corson technology. Production was stopped not only due to technical and economic considerations, but also for general organisational and conceptual reasons. The ash produced at the Dětmarovice power plant had very suitable qualitative features for use in the production of autoclaved aerated concrete and at large concrete plants as a partial replacement of cement. Within the framework of research conducted with the purpose of renewing the production of sintered artificial aggregate in the Czech Republic, concrete test specimens made with artificial aggregate based on high-temperature ash from Dětmarovice power plant (black coal), Otrokovice heating plant (brown coal) and additionally brown-coal fly ash from Hodonín power station were produced in 2007. As in previous work by J. Adámek, [4, 5], the mixture was designed with a focus on very high quality connective mortar. In practice, this means the use of a higher proportion of natural 0-4 mm aggregate and the use of 4-8 mm and 8-16 mm fractions of artificial aggregate. With quality aggregate based on ash from Dětmarovice power plant (the resistance to crushing of the 8-16 mm fraction = 4.5 N∙mm-2), a concrete cube strength of up to 54.7 N∙mm-2 was achieved. The submitted part of the experimental work is aimed at evaluating types of domestic high-temperature browncoal ash with regard to their prospective use as long-term and stable sources for the production of sintered aggregate. Another goal is to verify the ability of concrete made with such types of ash to attain the parameters of LC 50/55 lightweight high-strength concrete.