As the use of marginal-quality materials in pavement foundations and for structural layers in roads increases with the necessity to use more locally available materials in the most cost-effective manner, there is a greater requirement for improvement of these materials by stabilisation. Besides the traditional pozzolanic stabilisers such as lime and cement, there is a rapidly developing market for proprietary soil additives that make use of various chemical reactions during the soil stabilisation process. Although there is a marked increase in the use of bitumen emulsions for stabilisation, this paper concentrates on the use of chemical soil stabilisation. Recent findings with respect to the long-term durability of pozzolanic stabilisers, primarily in relation to the phenomenon of carbonation of the stabiliser and its reaction products are discussed. Numerous premature failures of roads and significant problems during construction have been attributed to carbonation. The application and use of certain non-pozzolanic chemical soil stabilisers (mostly strongly acidic, ionic, sulphonated, oil-based products) following a number of years of research and utilisation is discussed. It is concluded that when utilised correctly with appropriate soil materials, these products can be very cost-effective. (A)
Samenvatting