Evaluation of Sawdust Ash-Stabilized Lateritic Soil as Highway Pavement Material

Large quantities of sawdust waste are generated daily by the logging and lumbering industries, and their safe disposal is a major concern worldwide, whereas the properties of some lateritic soils make them undesirable for use in engineering construction. This paper presents the results of a laboratory evaluation of the characteristics of lateritic soil (LS) stabilized with sawdust ash (SDA), subjected to British standard light (BSL) compactive effort to determine their index, compaction, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) results. The results of the laboratory tests show that the properties of LS improved when stabilized with SDA. The particle-size distribution improved from poorly graded, sandy, gravelly material for 100% lateritic soil and silty material for 100% SDA to the gradation with 94.9-99.9% coarse aggregates of sand and gravel, described as gravelly sand and sandy gravel material for SDA-stabilized LS. The CBR results obtained from the study show that, using the Nigerian general specifications, the maximum CBRs of 19.4% (soaked for 24 h) and 24.1% (unsoaked) achieved for the mix proportion (70% LS + 30% SDA), which falls under American highway and transportation industry standards, can be used as subgrade material. This research provides results for the evaluation of SDA-stabilized LS as highway construction material, as it is based on CBR determination, a limited parameter that does not provide information concerning all important solicitations that flexible pavement materials are subjected to, even if still used in developing countries. Further work may be encouraged to assess the resilient modulus of this material under cyclic load as well as the assessment of permanent deformation of SDA-stabilized LS. (C) 2014 American Society of Civil Engineers.