Quality Control Assessment of Road Construction in Thailand Using the Dynamic Cone Penetrometer

Direct monitoring of the mechanical properties (e.g. stiffness and strength) plays a crucial role for quantitative evaluations and is also consistent with current mechanistic-empirical (M-E) pavement design procedures, which require the mechanical properties of unbound materials. In this study, a convenient dynamic cone penetrometer (DCP) was employed to assess the penetration resistance of unbound materials (e.g. crushed rock base, soil-aggregate subbase, sand embankment, natural subgrade etc.) in the laboratory and the road construction sites in Thailand in companion with the conventional compaction control tests. Penetration resistance of unbound materials in terms of DCP index divided by the deviation of compaction moisture content from the optimum moisture content (OMC) in companion with typical earthwork compaction acceptance criteria for a given material type was proposed to enhance construction quality control, to ensure proper compaction quality, to attain structural uniformity, and to facilitate quantitative evaluations of a controlled design parameter during road construction process. Ultimately, the moisture content had a significant impact on the mechanical behavior and needed to be limited after construction. On the other hand, the effect of RC on DPI of the compacted unbound materials was relatively minor compared to moisture content. The quality control assessment (QCA) parameter was also introduced in order to ensure proper compaction quality and to attain structural uniformity during road construction.