Evaluation of curing criteria for cold in-place recycling of asphalt

The current practice in Iowa simply controls the maximum moisture content in the cold in-place recycling (CIR) of 1.5 percent, whereas many CIR projects, struggling with unfavorable climate, have been overlaid successfully with higher amounts of moisture. The prior research was conducted to explore technically sound and more effective ways to identify minimum in-place CIR properties necessary to permit placement of the HMA overlay. Moisture loss indices were developed based on the field measurements from one CIR-foam and one CIR-emulsion construction sites. To calibrate the moisture loss indices, six CIR construction sites that include two CIR-foam sites, two CIR-emulsion (CSS-1) sites and two CIR-emulsion (HFMS-2s) sites, were proposed to be monitored using embedded moisture and temperature sensors. However, due to the lack of available CIR-emulsion sites nearby, one CIR-HFMS-2S emulsion site and four CIR-foam sites were monitored. The potential of using the stiffness measured by geo-gauge to supplement (or possibly replace) the moisture measurement by a nuclear gauge was explored in this study. A correlation between stiffness and moisture content was developed.