Natural hazards cause billions of dollars of damage to transportation facilities each year -- only flooding causes more damage than expansive soils. Nearly all types of transportation facilities have been affected by expansive soil behaviour and, as a result, many have failed or are no longer serviceable. It is imperative that the damage caused by expansive soils be controlled, and proper application of soil stabilisation methods can significantly reduce the damage that results from these problem soils. The purpose of this presentation is to discuss the phenomena associated with stabilising these soils, their behavioural patterns that affect stabilisation, and the initial and remedial stabilisation methods that can be applied to them. The factors considered include conditions requiring and allowing stabilisation, changes of properties with time, the effects of stress history and desiccation, the influence of climate, and the effects of physicochemical environments. Effects that can be improved by stabilisation are pinpointed. stabilisation methods are described that improve selected properties of expansive soils by mechanical and chemical means. Well-established methods are discussed along with those that are very promising. Examples of remedial treatments are discussed. It is concluded that there is a need for analyses of all alternatives and for stabilisation during construction rather than costly remedial projects. Research needs are outlined that can improve our understanding of the stabilisation requirements of these problem soils.
Samenvatting