Construction on Expansive Soils in Semi Arid Zone

The detrimental consequences of expansive soils are more pronounced in areas having hot climate with low rainfall; most part of Pakistan falls in semi-arid zone. A study was under taken to find a cheap and simple method of treating expansive soils, mostly found in southern part of Pakistanl. Hydrated lime is the cheapest options because it is available in abundance in Pakistan. The study evaluated the effects of hydrated lime on compacted high plastic clay having high salt contents with focus on establishing a suitable range against high potentials for volume change, low strength, poor permeability and dispersivity. It was found that the lime is a good stabilizer. 6–10% of the lime by weight is recommended; CBR (soaked) strength increases to 34%, OMC increases by 3% with slight decrease in maximum dry density. and swell potential of compacted soil was reduced to < 5% whereas with addition of 10% limes the shrinkage was reduced to 4%. Addition of 10% lime increases permeability by six folds and treated soil behaved as non-dispersive. However, the use of the lime, in excess of 10% has adverse effects on strength of the soil.