Nauka ta progres transportu (Apr 2017)
THE STUDY OF DEFORMATION CHARACTERISTICS OF SOIL MATERIALS WITH THE USAGE OF WASTES
Abstract
Purpose. More often the qualified building materials are replaced by the industrial wastes for environmental improvement. This refers to both metallurgical slags and biological solids of water treatment plants. In order to understand the possibilities of their usage it needs studying deformation properties of composite soil materials with industrial wastes addition. Methodology. The soil of real buildings and structures foundation is in the complicated conditions and the stress-strained state. While studying this state the total deformation modulus Е0 is used as the deformation characteristic. This one is determined according to the results of sample soil testing in the compression instrument (odometer). This instrument prevents the possibility of lateral expansion of sample soil under the vertical load. Findings. As a result of the testing the compression curves are plotted as the dependence of the porosity coefficient on pressure. These data allow determining the compressibility coefficient and the strain modulus. It is found that a biological solids addition increases the compressibility coefficient four times compared to the clay. The two types of samples are compared. The first type contains 50% of biological solids. The second type contains 50% of biological solids and 50% of slag. The comparison shows that the second type is compressed twelve times less. An addition into the clay of biological solids increases the strain modulus from 7.8 to 20.3 MPa. The slag increases the strain modulus to 52.7 MPa. Originality. While making the composition based clay materials the functional groups of biological solids interact with hydroxyl groups which are placed on the surface of clay particles and form a spatial structure. Besides an addition of biological solids contributes to peptization, soil aggregates destroy themselves, and form contacts between separate particles. It causes the decrease of soil compressibility due to the total porosity decrease. An addition of slag results in formation of optimal structure where particles of less sizes are placed in layers between bigger particles. Practical value. An application of biological solids and slag provides the increased load-carrying capacity of soil, extending of raw material sources while improving the environmental situation in the cities. Also it provides the recycling of reinforced soil.
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