Terminal evaluation of lateritic soils studies

Final evaluation covers the period 6/67-2/75 and is based on interviews with persons in the United States familiar with lateritic soils and a survey of knowledgeable firms and organizations throughout the world. The laterite studies developed satisfactory criteria and procedures for identifying, classifying, and testing lateritic soils and tropical black clays. Use of the design methods, specifications, and construction control procedures recommended by the studies has permitted locally available soils to be used successfully in an increasing number of tropical highway projects, with maintenance costs comparable to those for other materials. Construction cost benefits have been realized on one out of four projects, for an estimated total of $1 million on 14 projects in Southeast Asia and Africa. The overall reliability of the laterite reports is good to excellent. The reports have received significant world-wide distribution. Recommended test methods, design procedures, and specifications are used by a third of the survey respondents. Use is greatest in Africa. While the laterite reports are princupally used in the design, construction, and maintenance of highways, there is some interest in using laterite soils for home building and dam construction. It is recommended that performance studies on construction with lateritic soils and black clays be conducted after several years of service and that the use of laterite in constructing housing and dams be studied. Future practical engineering studies on road surface treatment, soils of arid areas, and expansive clays are recommended.