Fly ash for concrete

This product is generated in hard coal-fired heat and power plant. Coal after being ground to the form of fine dust, is insufflated into the furnace and burnt at the temperature of circa 1400°C. During the process of burning, mineral parts of rocks contained in hard coal that can't be burnt, are melted completely or partly. The majority of melted mineral dust-like particles is transported by electrostatic or mechanical precipitation from the flue gases of furnaces and kept in filter as fly ash. Fly ash from hard coal is a fine powder, which is mainly composed of spherical glassy particles. It is gathered in siloses and afterwards - loaded and transported dry with tankers. Production of fly ash for concrete is a subject to continuous quality control as well as optimization of physical and chemical qualities, specially concerning loss on ignition (LOI).

Properties

Fly ash has the form of fine mineral powder. Its colour varies from light to dark gray and light brown. It consists essentially of silicon dioxide, aluminium and iron oxides. Apart from that it consists - the same as natural rocks - of different kind of trace elements and of non-burnt hard coal parts as coke particles. In consequence of thermal processing in furnace, hard coal fly ash enters, in the presence of lime in room temperature, the pozzolanic reaction. It results in rising, the same as by hydration of Portland cement, of microscopic, crystalline lime-silicious and lime-aluminous hydrates that evolve into hard rock. Taking into consideration chemical composition, fly ash resembles volcanic ashes and soils like trass as well as pumis that have been known for 2000 years. In application of fly ash the significant role also play physical properties. Glassy, mostly spherical particles have diameter between 0,5 and 200um. Average grain diameter is between 5 and 20um. The grain density of hard coal fly ash ranges from 2200 to 2500 kg/m3 and the bulk density is between 800 to 1100 kg/m3

Application

Fly ash as artificial puzzolana enables cement reduction. Thanks to its valuable properties and competitive price, it can be applied as an admixture in concrete and cement, addition in the production of concrete products (e.g. vibropressed concrete pavers), bricks and concrete blocks as well as filling and ground improving material.
Fly ash offered by Renevis meets entirely the requirements of the norm PN-EN 450 Fly ash for concrete and is marked with CE symbol according to the EC Certificate of Conformity issued by Building Research Institute. There has been also issued the National Declaration of Conformity, supported by the building marking symbol B for this product.
Moreover we obtained the sanitary certificate issued by State Sanitary Office allowing hard coal fly ash from EC Wrocław and EC Czechnica (both units are owned by ZEW Kogeneracja S.A.) to be used as admixture in concrete.