As part of a study of aspects of normal road-building practice in tropical countries, the states of compaction achieved in road bases and earthworks were investigated at ten road construction schemes in east Africa. In addition, where possible, controlled compaction trials were carried out. The most significant conclusion from the investigation is that the states of compaction achieved in the field correspond quite closely with those obtained in full-scale compaction tests carried out at the transport and road research laboratory. The relation between compactive effort, moisture content and the dry density obtained in the field followed accepted patterns; overstressing was noted on a uniform sand soil. The optimum moisture condition for compaction in the field was close to the optimum moisture content in the b.s. compaction test 2.5 kg (5.5 lb) rammer method and simple and rapid methods of appraising the moisture conditions were effective in maintaining the moisture contents within an acceptable range. The study showed that the states of compaction commonly specified for tropical roads can be attained under normal working conditions. (Author/publisher)
Abstract