The Use of Ash and Slag in Road Construction in the Position of Environmental Safety

Abstract

This paper explores the practice of using ash and slag and fly ash from thermal power plants in road construction as one of the ways to dispose of industrial waste. The purpose of the study is to determine the chemica l composition of TPP ash and slag to study the possibility of using it as a raw material for road construction. To achieve the goal, the following tasks were set: to determine the main physical and chemical properties of ash and ash and slag from thermal power plants, to give an environmental assessment of the use of these wastes in road construction. Chemical analysis of ash and slag from Zmievskaya, Krivorozhskaya, Trypilskaya, Slavyanskaya TPPs was carried out to determine the main components: SiO2, Al2O3, Fe2O3, CaO, MgO, SO3, Nа2О and К2О. The content of heavy metals was determined using the method of atomic absorption analysis. The migration ability of heavy metal compounds from the roadway using ash and slag in the construction of roads has been studied using the construction of concentration-logarithmic diagrams. To predict the migration of heavy metal compounds into the environment when they are used in road construction, a separate dependence of the concentration of the most probable ions was plotted (for example, cuprum) [Cu(OH)n 2-n] on the pH of the environment. The lack of migration of cuprum compounds in a neutral and alkaline environment has been proven, which makes their use safe. Similar calculations were made for other metals.

Geoecological Analysis of Threats of Using Phosphogypsum in Construction of Roads

“…There was possible presence of baryte, as indicated by strips measuring 0.384; 0.307; 0.208; 0.153; 0.127 nm. Taking into account the mineralogical phase composition of the initial raw material and industrial phosphogypsum, we may quite confidently assume that in the conditions of such a complex of chemical components and factors, phosphogypsum promotes the development of sulfates, phosphates, carbonates and halides with complex composition and large share of anion isomorphism (Krainiuk, 2004). Furthermore, as demonstrated by the X-ray analysis of the samples, high concentrations of sulfates and chlorides, which together with the analyzed metals form well-soluble compounds (except PbSO 4 ), and thus can migrate in soil to large distances from phosphogypsum piles or phosphogypsum-strengthened soil.…”

“…There occur dehydration and processes of consolidation, decrease in phosphogypsum moisture. Because of wind and water erosion, infiltration, heavy toxic components migrate to soil, groundwater and air around the phosphogypsum stockpiles (Krainiuk, 2004).…”

“…The suggested recommendations are for materials used in making road bases and coatings, and also roadway infrastructure. Industrial wastes could also be blast furnace slag, chemical industry wastes, ash slag, phosphogypsum, galvanic sludge, etc, which release chromium, lead, nickel, cadmium, ferrum, cobalt, cuprum, aluminium, manganese, hydrargyrum, zink, barium, arsenic, fluorine, etc compounds into the environment (Krainiuk, 2004).…”