Various Additives Used as Alternative to Conventional Road Construction

The Western Cape Provincial Administration in South Africa initiated an experimental study to investigate the use of various additives as an alternative to conventional regraveling construction of a gravel road. The in situ material was reworked and stabilized with nontraditional stabilizers. A control section, together with a section stabilized with a traditional stabilizer, was used to compare the performance of the various sections over time. Three sections were also sealed with a bituminous surface and monitored over time. Monitoring of the sections was done either up to the point at which the road surface broke up or for 2½ years. The performance of the different monitoring sections, representing different types of additives and varying-quality (marginal) in situ material—but under the same conditions of climate, traffic volume, and construction technique—were monitored and compared over time. Four main areas of performance were monitored: during construction, in the laboratory, over time, and in economic terms. This paper provides background on the different additives used, a summary of the experimental design, and a brief discussion of the various products. It emphasizes construction and performance monitoring over time and analysis of the results. Apart from interesting observations, conclusions are made by looking not only at performance but also by taking vehicle operating and life-cycle costs into consideration.