The field compaction of lateritic pavement layers in a tropical environment

Abstract

Even though laterites and lateritic soils are known to be weak as aggregates, in the tropics they are extensively used as economic base and subbase material. At the same time, there is a tendency among Contractors to select high-capacity compaction plant in order to achieve good levels of compaction during earthworks and in pavement construction. The effects of high capacity compactive effort on relatively weak lateritic soils, have been a challenge for practitioners in the tropics. In order to gain a better understanding of the implications of this practice, a study of compaction of laterites and lateritic soils in a pavement layer was undertaken across Ghana. This paper presents part of the results of that study. The results of field compaction on lateritic soils that were being used as pavement layers on five road construction sites in different climatic zones of the country are presented. The field tests were complemented with a set of laboratory tests. The results are analyzed in terms of the effect of compactive effort on the levels of compaction and also in terms of the degree of saturation. The influence of particle breakage occurring under both field and laboratory compaction on the results are also discussed. The results show that the compactive efforts on site appear excessive and are leading to large particle breakage. When analyzed in terms of degree of saturation the low levels of compaction achieved on some sites despite the high compactive efforts are explained.