First Look at Full Depth Reclamation Technique with Cement Stabilization for Expedient Airfield Pavement Reconstruction

Abstract: Cold in-place recycling, such as the full-depth reclamation (FDR) technique, could significantly impact the US Department of Defense's ability to restore severely deteriorated asphalt pavements in logistically challenging locations. The present study discusses the laboratory performance of FDR mixtures with cement (FDR-C) and provides a regression model that considers basic mixture characteristics and lab performance to determine the minimum stabilizer content during expedient asphalt pavement reconstruction. Fifteen FDR mixtures were sampled from representative asphalt pavements and subjected to the unconfined compressive strength (UCS) and indirect tensile strength (ITS) tests at different cement contents. Basic geotechnical data were also collected, such as particle size distributions, fines content, Atterberg limits, and density curves. The laboratory test data were analyzed to determine the minimum cement content required to achieve UCS thresholds of 250, 500, and 750 psi. The UCS and ITS data were plotted against each other to examine a correlation among these performance indicators. Preliminary thresholds were determined for the ITS parameter corresponding to the existing UCS thresholds. Lastly, correlation and regression analyses were conducted to investigate the feasibility of predicting minimum cement content requirements for representative FDR mixtures. From this study, the existing UCS threshold of 750 psi could only be achieved with considerably high cement contents, which exceed the maximum cement content commonly required for cement-stabilized granular layers for airfield pavements. Good-quality FDR mixtures required less than 2.5% cement to achieve a UCS of 500 psi, while marginal-quality FDR mixtures met the UCS threshold of 500 psi with cement contents between 4.5% and 6%. The UCS and ITS tests yielded a good correlation. The ITS test exhibited a better ability to delineate the performance of FDR mixtures with and without cement. A simple relationship consisting of basic geotechnical properties was developed to aid in the selection of minimum cement content for expedient airfield pavement reconstruction projects via FDR.