Characterizing Lime- and Cement-Treated Soil with the PM Device at a Full-Scale Pavement Test Track

In this paper, the plastic mold compaction device (PM Device) was used successfully during full-scale construction of lime- and cement-stabilized pavement layers for which strict quality control measures were taken, such as multiple spread rate calibration, frequent moisture contents, and close attention to compaction timing and density measurements. Even with these precautions to minimize variability, there was quantifiable variation in density, unconfined compressive strength (UCS), and elastic modulus ($E$) for soil–cement and soil–lime mixtures. Over the 61-m test section, density varied by 5.2% for soil–cement and by 5.0% for soil–lime, UCS varied by 861 kPa for soil–cement and by 246 kPa for soil–lime, and $E$ varied by 2,628 MPa for soil–cement and by 1,036 MPa for soil–lime. There also were noticeable differences in PM Device density and $E$ measurements compared with nuclear gauge and falling weight deflectometer–calculated modulus. This paper also serves as the first known and documented use of the PM Device with lime-stabilized material, and is the first known and documented comparison of PM Device specimens and beams compacted with a Proctor hammer. Compared with other field projects in which the PM Device was implemented, the variability of density and UCS in this project was lower than in other typical Mississippi Department of Transportation (MDOT) projects. When using the data collected at the National Center for Asphalt Technology (NCAT) test track as a baseline for soil–cement materials, variability likely will be no less than 5% for density as a percentage of the target density and 75% for UCS as a percentage of the average UCS value when using current MDOT construction protocols.