At the request of the lignosulphonate manufacturers in South Africa, a reassessment of the use of lignosulphonate in unsealed roads was initiated. A detailed study of the literature was conducted and a state-of-the-art review prepared. This was followed by a comprehensive laboratory testing programme. Based on the laboratory results, a number of controlled experiments were constructed which are currently being monitored. To date, the investigation has found that the guidelines developed for the United States are generally inappropriate for the improved product, especially under local conditions. Interim guidelines for the use of the product have been compiled and monitoring and experimentation will continue in order to develop appropriate material, climatic, construction and rejuvenation guidelines for various material, climatic and traffic conditions. The interim guidelines are based on the performance-related material specification used for southern African unsealed roads, and include maximum size, grading, plasticity, strength and hardness parameters. Conservative interim performance prediction factors have been developed to enable economic analysis. Construction, maintenance and rejuvenation guidelines have been prepared for various application techniques. (a)
Samenvatting