Stabilization of expansive soils using ELECTRIC-ARC furnace slag for subgrade construction.

Abstract

Expansive soils show high volumetric changes with changes in moisture content. During the wet season, they expand and upon evaporation during the dry season, they shrink. Because of this alternate swelling and shrinkage behaviour, structures founded on them are prone to damage. In Uganda, the expansive soils are found especially in arid and semi-arid regions (northeast), eastern region along the slopes of mountain Elgon, some parts of northern Uganda and along the Albertine region. With rapid growth in the steel and iron manufacturing industry throughout the world, huge amounts of waste materials such as slag are generated. According to (Akinwumi, 2014), the current world’s annual production of slag is estimated to be 90-135 million metric tons. Uganda has a total steel market of around 585,000 tons per annum and the consumption of steel per capita currently stands at around 15kg/capita per annum (Khisa, 2018). One of Uganda’s largest producers, Roofings Group, generates approximately 1-3 tons of Electric-arc Furnace (EAF) slag per 60 tons of steel produced. This not only poses a disposal problem but also contributes to environmental contamination. Utilisation of EAF slag as an alternative to construction materials may effectively contribute to sustainability and curb its adverse effects on the environment. In this research, laboratory tests were performed on expansive soils obtained from Nakapiripirit district, Northern Uganda. The tests aimed at assessing the effect EAF slag has on the engineering properties of the soil. The tests were done at EAF slag dosages of 0%, 5%, 10%, 15%, 20% and 30%. Slag was used in incremental dosages with reducing percentages of expansive soils. Test results confirm that the engineering properties of expansive soils are improved with treatment of the soil using EAF slag.