A joint research project between the Ministry of Transport and
Communications, Kenya and the Transport and Road Research Laboratory. UK is a study of soil compaction at low moisture contents in arid areas. This paper describes part of the study in which an investigation has been carried out on a well-graded clayey gravel designated as a road base material for a road project in NW Kenya. The investigation comprised laboratory testing, pilot and full-scale trials to examine the density and strength characteristics of the material at low moisture contents. The results were compared with those obtained when compaction was carried out under normal requirements
at optimum moisture content.
It was shown that high densities were achieved at low moisture contents both in laboratory tests and in the field trials and that vibrating compaction methods were preferred. Conventional construction plant and operating techniques were successfully applied and specifications for compaction in Kenya were readily exceeded. Field CBR measurements for the base constructed at low moisture contents were lower than those obtained in the laboratory. Analysis of pavement strength parameters including deflection, radius of curvature and structural number showed that the trial sections
were different but indicate that the designs were adequate for a life of 0.5 million equivalent standard axles. The road trials constructed with bases at different initial moisture contents have performed equally well for two years but further information on the longer term performance can be made on the use of dry compaction is required before final recommendations can be made on the use of dry compaction.
Editors: J. O. Akinmusuru et al., Ninth Regional Conference for Africa, Lagos. Soil Mechanics and Foundation Engineering, Volume 1, September 1987, pp. 211-226. A. A. Balkema - Rotterdam. pp. 18