Definition of Specifications for Use in Pavement Course of Lithostabilized and Cement-Treated Fine Lateritic Soil in the South of Benin

Abstract

Road construction is expensive for governments, especially if road materials are dwindling in the project area, as is the case in southern Benin. The solution of lithostabilizing the soil with lagoon sand cannot be implemented without specifications for monitoring its execution. This study aims to define a set of specifications for the use of litho-stabilized bar soil and cement-improved litho-stabilized clay soil in roadway pavement layers. To achieve this objective, a statistical analysis of data from previous formulations is first conducted to identify specifications of the composites suitable for use in the base course. Secondly, two additional formulations are produced for which the range of compaction water content based on Proctor points around W OPM , is researched. These analyses revealed that the fine lateritic soil materials suitable for litho-stabilization are classified as I2 according to the GTR 2023 classification, with an average plasticity index ranging from 22 to 27 and a percentage of fines particles between 30% and 45%. For use in sub-base courses, the composite obtained should generally have a plasticity index of at least 20, a fines particles percentage of at least 30%, and a grading curve range is found in the present study. The litho-stabilized soil composite is suited for T1, T2, and T3 traffic categories (CEBTP classification). For its application, the compaction water range should be in the interval [0.90 OMC ; 1.20 OMC]. As a base course, the material should be improved with a cement content of 3.5% to 4%. It is intended for traffic categories below T5 (according to NF P98-086). These results confirm the relevance of litho-stabilization on bar soil and the use of the composites derived from it for low and moderate traffic in pavement base courses.