Strength and deformation characteristics of ash and slag mixture

Building Materials

Burning of coal and brown coals at thermal power plants (TPP) is the main method of generating electric and heat energy in the Russian Federation. Inasmuch as a result of coal combustion a considerable amount of waste is produced (up to 50% of the whole mass of base coal) the quantity of the gained ash slag in a landfill is measured with hundreds of millions of tons. Insufficient level of knowledge about strength and deformation properties of these artificially-produced soils for building motor roads’ roadbeds and embankments substantially limits the scope of using the ASM in the Russian Federation. In this connection, the purpose of the research is to study a complex of the ASM’s engineering properties for evaluating its use as a soil material for building embankments of motor roads’ roadbeds and leveling operations. In the frames of the research, there have been tested the ASM samples, obtained from burning Ekibastuz coal in boilers with dry ash removal. Samples were made with different density and humidity. For each density value, there were determined the modulus of deformation and the elastic modulus. The authors have determined the values of the angle of internal friction and specific cohesion of the ASM depending on the moisture and normal pressure. Consolidated and drained tests in triaxial compression devices have allowed to determine the values of the secant elastic modulusand the Poisson's ratio of the ASM’s with different density. As a result, it was found that an increase in the ASM’s density significantly increases the elastic and deformation modulus, the angle of internal friction, and the cohesion of this artificially-produced soil. However, after a certain degree of compaction, the cohesion value begins to decrease. Increasing the moisture content of the ASM samples decreases the modulus of elasticity and general deformation, but it has an ambiguous effect on the angle of internal friction and cohesion.