ABSTRACT
Roads in under-developed regions require adequate in-situ material for their construction, but the normal test methods to indicate their suitability can be expensive and difficult to carry out. Attempts to reduce testing costs by using mathematical or graphical prediction models have been shown to be of limited reliability. Previous research on synthetic soils indicated that certain parameters could potentially be predicted using a modified Atterberg liquid limit value and the quantity of the ‘clay’ fraction present. However, these models could not be applied to natural soils, apparently due to the presence of non-clay (‘inert’) particles in the ‘clay’ fractions. A preliminary study was therefore undertaken to investigate the clay-sized fractions of some natural soils using X-ray diffraction analysis. The study indicated that a significant amount of non-clay mineral particles were present in many of the clay-sized fractions of the soils.
