SMALL-PIECE SEMI-DRY-COMPACTED CONCRETE PRODUCTS BASED ON WASTE FROM ENERGY GENERATING ENTERPRISES

Abstract

The article investigates the fly ash from Burshtyn TPP for its use as a component of binding raw material compositions for the production of small-piece concrete products. Based on the integrated characteristics of chemical and phase composition, it was found that the ash is ultra-acidic, is an amorphous substance and is characterized by low hydraulic activity. Calcium-containing additives (slag cement and/or hydrated lime) and an alkaline aggregate (soda solution) were used to activate the ash glass. The charges compositions using ash at the level of 75–90 wt. %, in which the type and amount of activator and the type of aggregate (alkaline solution or water) were subject to variation in order to optimize the technological parameters of the materials. For materials formed at a pressing pressure of 25 kgf/cm2 and hardened under steaming conditions, a positive effect of cement, alkaline aggregate and combined hardening activator on the properties of materials, their appearance and geometric dimensions was established. Such materials have a low level of mechanical properties; only certain charge compositions allow for a mechanical strength grade of M50 to M75. In order to improve the final mechanical strength of materials, the influence of pressing pressure, moulding moisture and hydrothermal treatment methods (steaming or parboiling) on the properties of materials of individual compositions was investigated. It has been determined that increasing the pressure up to 300 kgf/cm2 and autoclave treatment of semi-finished products can significantly improve the level of mechanical properties. The rational compositions of binder compositions with a high degree of fly ash use (75 and 77 wt. %) were determined, on the basis of which water-resistant samples of asphalt concrete grades M 125 and M200 in terms of mechanical strength and grade F25 in terms of frost resistance were obtained by semi-dry pressing. The materials are recommended for the manufacture of products for the construction of sidewalk elements, as well as wall small-piece concrete products.