Dynamic Cone Penetrometer Testing on Airport Subgrade Soils

Dynamic Cone Penetrometer Testing on Airport Subgrade Soils Researcher: Michael Watts REU Sponsor: Dr. Mike Mooney

What is a Dynamic Cone Penetrometer (DCP)? 8 kg. hammer drops 575 mm Hammer hits an anvil sending the cone-tipped rod into the soil

Dynamic Penetration Index (DPI) l l l A ruler is used to measure the distance rod sinks into the soil. DCP measurements are recorded as a Dynamic Penetration Index (DPI) DPI = depth / # of blows for cone-tipped rod to reach that depth

Uses of the DCP l l Quick test for characterizing subgrade soils Correlations have been developed between DPI and a soil strength value called the California Bearing Ratio (CBR) CBR values are used in pavement design Recent efforts have focused on developing correlations between DPI and Resilient Modulus (Mr), rather than correlations for empirical tests such as the CBR test

Purpose of Research l l Test effectiveness of DCP as an airport subgrade soil profiling tool To compare Mr calculations based on DCP to Mr calculations from a non-destructive test, Spectral Analysis of Surface Waves (SASW)

Test Methods l Goldsby and Seminole Airports – Holes drilled in asphalt using gas core-driller – DCP tests were performed either in the core-hole or in a offset hole – Soil was removed for lab tests using a hand auger l Shawnee Airport – Same procedures as Goldsby and Seminole, except SASW tests were performed prior to coredrilling at test sites

Results of DCP Testing

If only REU lasted until December. . . l Further study could have focused on: – Exploring further the relationship between DPI and soil material/water content – Comparing Mr calculations based on DPI to Mr values derived from lab tests on the same soil – Exploring the differences in Mr values based on DCP testing from Mr values based on SASW testing