Use of Road Stabilizers in Sensitive Environments

Road infrastructure is key for any developing country to enable its expansion such as those in Africa. Natural road construction materials can become depleted and increasing traffic loads produce higher maintenance requirements, leading to research to develop additives that can be used to enhance the engineering properties of available pavement soils. Providing all weather roads for large vehicles in rural areas, such as Northern Namibia, are often based only on the available soils, involving compaction and use of stabilizers, is required to both provide a suitable load bearing road surface and maintain the road network. The region is also environmentally sensitive to any potentially adverse impacts of chemicals that may be released into the environment during construction or as breakdown products. A number of road stabilizer products are available and the choice of stabilizer must take into account both its specific properties and the sensitivity of the environment where it is to be used to any environmental impacts. The main stabilizer types are cementitious, bituminous and chemical, with the latter broken down in a range of materials including synthetic polymer binders, organic and ionic compounds, salts, enzymatic products and combinations thereof. Twenty available stabilizer products were considered in terms of their environmental properties and assessed against the published literature and the general findings reported in terms of the overall ranking of the environmental impact of stabilizer types.