Correlation between the Dynamic Cone Penetrometer and the California Bearing Ratio for Subgrade Soils

The assessment of soil bearing capacity is fundamental for pavement design, but the traditional California Bearing Ratio (CBR) test is time-consuming and costly. The Dynamic Cone Penetrometer (DCP) offers a rapid and cost-effective field alternative. This study develops and validates correlation models between CBR and DCP for clayey, granular, and clayey-granular soils. The analysis was based on 15 CBR tests and evaluated against four established DCP correlation models: Kleyn and Van Heerden, TRL Overseas Road Note 8, US Corps of Engineers, and MOPT Colombia 1992. Results demonstrate that a cubic regression model consistently provides the best fit for all soil types, achieving coefficients of determination (R²) as high as 0.96 for granular soils and exceeding 0.89 for clayey soils. The findings confirm that the DCP test, when paired with the validated cubic correlations, constitutes a precise and efficient tool for estimating CBR, covering efficient on-site testing and information for preliminary design in pavement subgrade.