Compaction Verification of Lateritic Soil Using Electrical Resistivity: A Laboratory Study

Constructing road pavement and highways in tropical countries usually requires using lateritic soils as pavement material. The degree of compaction during the placement of these lateritic soil materials needs to be verified for compaction quality control. The conventional geotechnical methods usually used in compaction verification are invasive, laborious, and time-consuming. Increasingly, rapid methods are needed for such compaction verification in the field. Theoretical relationships suggest that the degree of compaction of compacted soils can be evaluated using electrical resistivity measurements. A laboratory investigation was therefore conducted on in-mould compacted lateritic soil specimens to explore the possibility of using electrical resistivity measurements for rapid compaction verification. The results show that the electrical resistivity of compacted lateritic soil is sensitive to slight variations in water content. A new relationship was established to estimate the lateritic soil's relative compaction and degree of saturation using the measured electrical resistivity with a prediction accuracy greater than 93%. Two correlation parameters, & alpha; (related to the relative compaction at zero air voids) and & beta; (related to the effect of moisture content on resistivity), can be easily obtained from laboratory calibration. The result from this study shows that the electrical resistivity measurement can be a very useful rapid compaction verification tool for lateritic soils in the field after careful laboratory calibrations.