Contaminated dredged soil stabilization using cement and bottom ash for use as highway subgrade fill

Abstract

Large amount of sediments are dredged from connecting drains of River Yamuna as a part of its regular maintenance in Delhi. These dredged soils generally considered as waste due to its poor engineering properties. In this study attempt has been made to improve strength, durability and immobilize contaminants of the contaminated dredged soil collected from Najafgarh drain by mixing it with different proportion of cement–bottom ash mix so that it can suitably fulfill the requirements of highway subgrade materials. Compaction test, California bearing ratio test, wetting and drying test, toxicity characteristic leaching procedure leachate test and scanning electron microscope test were performed on the contaminated dredged soil specimens and the results indicated that cement–bottom ash mix was effective in improving the engineering properties of the contaminated dredged soils. Also, the test results of the contaminated dredged soil stabilized with cement–bottom ash mix were better in comparison to cement alone. From the study it reveals that the optimum proportion of additive to be used to improve properties of the contaminated dredged soils was 10% cement + 10% bottom ash mix for use it as a highway subgrade fill materials.