Working with expansive soil as pavement subgrade is not technically easy due its poor workability and insufficient capacity to support the imposed cyclic traffic loading. For satisfactory performance of the pavement structure constructed in such foundation hence the properties of the weak subgrade have to be modified. One of the ideal solutions to these problems might be looking towards naturally abundant and industrial waste materials that are produced in large quantities as stabilizing agent for clay subgrades so that the instability concerns can be alleviated. This study hence primarily aimed at experimentally scrutinizing the stabilizing potential of waste ceramic dust and natural lime in modifying geotechnical properties of the highly plastic subgrade material. Both the separate and combined effects of the two stabilizing agents were investigated with respect to mitigating the key parameters required for stable road construction. The degree of improvement for various mix ratios were compared with the design and requirements of Ethiopian roads authority specifications for road construction. Accordingly, the optimum dosage for natural lime was 6% whereas that of the waste ceramic is 20% for safe road subgrades. It was also indicated that natural lime is more powerful than the waste ceramic dust from effectiveness point of view. The conducted experimental test revealed that the response of soil parameters to variation in amount of stabilizers in the separate application method is more sensitive for natural lime than the waste ceramic dust. The improvement rate in magnitude of the required geotechnical parameters in the combined case is by far greater than the separate application of the additives.
Keywords: Expansive subgrade; Limestone; Stabilization; Waste ceramic dust.
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