Suitability of Ceramic Dust Waste and Plastic Waste Fiber Mix to Improve the Strength of Subgrade Soil

Abstract

Expansive soils mostly cause significant damage to structures such as buildings, pavements and bridges. Therefore, the objective of this study was to quantify the improvements achieved on the weak subgrade soil strength due to mix of plastic waste fiber and ceramic dust waste on expansive clay soils of Jimma town. Demolished and waste ceramics were collected from Jimma town of different construction sites and crushed and powdered manually by means of hand and sieved through 75µm sieve size. Plastic wastes used for this study are Polyethylene Terephthalate (PET) plastic type are collected from JiT campus disposal holes, cleared and cut down to strips to having approximate thickness of 2-4mm and length 7-10 mm. The percent proportion of ceramic dust waste utilized was 5 to 30% and percentage of plastic fibers 0.5 to 2.5% by dry weight of soil. Firstly, the optimum percentage of ceramic dust waste was determined from laboratory test by mixing varying percentage of ceramic dust waste with clay soil. Then the optimum percentage of ceramic dust waste was used as constant and mixed with the varying amount of plastic fiber and expansive soil. Finally the optimum percentage of plastic waste fiber added was determined. Moisture content, particle size analysis, Atterberg limits, linear shrinkage, free swell, specific gravity, compaction, CBR and UCS tests were conducted. The CBR value of soil increased from 1.03% to optimum value of 5.80%, UCS value also increased from 83.15 kpa to 421.14 kpa (for immediate test) and 464.45 kpa (cured for seven days taste) by increase of ceramic dust waste from 0 to 30%. Laboratory tests revealed that the ideal level of ceramic dust waste as 20%. Clayey soil with 20% (optimum) of ceramic dust waste indicated just minor increment in the quality of soil, repressing its utilization for ground changes. To additionally build the quality of the soil the optimum percentage of ceramic dust waste mixed with various level of plastic fiber. Endeavors have been made with 20% (constant) ceramic dust waste and different rates of plastic fibers. The CBR value increased from 5.80 to 8.30%, UCS value also increased from 421.14 kpa to 744.61 kpa for immediate test and 464.44 kpa to 871.75 kpa for seven days cured test by increase of plastic fiber from 0.5 to 2.5% with optimum value of ceramic dust waste (20%) by weight of dry soil. Laboratory tests revealed that the ideal level of ceramic dust waste as 20% and plastic waste fiber as 1.5% by weight of dry soil. Ceramic dust waste treatment in clay soil enhances strength but to decrease brittleness in soil specimen, increase ductility behavior and to improve more, expansive soils reinforced with plastic fiber. An optimum content of ceramic dust (20%) with 1.5% (optimum) of plastic fiber by weight of dry soil is recommended for strengthening weak subgrade soil