Soil-stabilised and hydraulically bound mixtures used in road pavements

The level of service required from a road is a function of the importance of the route and its traffic, and, hence, the materials comprising the pavement infrastructure must be capable of coping with the performance requirements that the traffic demands, within the financial resources available. Typically, pavements that carry in excess of 50 vehicles per day require more than natural gravel in the structural layers in order to perform adequately (Figure 7.1). The improvements required to address this need include

As an alternative to the costly importation of off-site high-quality materials from afar to provide high-quality pavements, the treatment of in situ and/or off-site locally available materials with some form of mechanical or chemical stabilisation can often provide an economical solution to the need to provide for greater traffic loads. Such stabilisation treatments are commonly applied to subgrades, capping and sub-base layers; in many countries also – but rarely in the UK – these treatments are also applied to base courses. The selection of the type of treatment depends on the engineering properties desired from the various layers of the pavement structure, and on the prevailing environmental conditions. In practice, however, it must also be acknowledged that differences in philosophy exist between developed and developing countries regarding the use of soil stabilisation techniques to treat subgrades and to enhance the structural layers of pavements.