Expansive clayey soils usually exhibit great volume change with any moisture variation. The soils are also weak and have limited strength. These features cause limitations and high risks for constructing dams, highways and other engineering structures on such soils. A common technique to overcome the weaknesses of the clayey soils is to stabilize them using appropriate additives. In the present study, with an environmental approach steel industry by-products (slag) and waste fibers from carpet manufacturing (acrylic fibers) were added to two types of expansive soils to evaluate likely improvement effects. The selected expansive clays include of bentonite clay (B) and a composition of bentonite clay with 10% of local ordinary clay(C+10B) kashida; TEXT-ALIGN: justify; LINE-HEIGHT: normal; TEXT-KASHIDA: 0%; MARGIN: 0in 0in 0pt" Key words : Clay soils, expansive soil, free swell, swell pressure, modifier, slag, fiber, optimization
