Development of Moisture Loss Index Based on Field Moisture Measurement using Portable Time Domain Reflectometer (TDR) for Cold In-place Recycled Pavements

Abstract

The practice of asphalt pavement recycling has grown rapidly over the decade, one of which is the cold in-place recycling with the foamed asphalt (CIR-foam) or the emulsified asphalt (CIR-emulsion). Particularly, in Iowa, the CIR has been widely used in rehabilitating the rural highways because it significantly increases the service life of the existing pavement. The CIR layer is typically overlaid by the hot mix asphalt (HMA) to protect it from water ingress and traffic load and obtain the required pavement structure and texture. Most public agencies have different curing requirements based on the number of curing days or the maximum moisture contents for the CIR before placing the overlay. The main objective of this study is to develop a moisture loss index that the public agency can use to monitor the moisture content of CIR layers in preparation for a timely placement of the wearing surface. First, the moisture contents were measured in the field using a portable time domain reflectometry (TDR) device. Second, the weather information in terms of rain fall, air temperature, humidity and wind speed was collected from the same location. Finally, a moisture loss index was developed as a function of initial moisture content, air temperature, humidity and wind speed. The developed moisture loss index based on the field measurements would help the public agency to determine an optimum timing of an overlay placement without continually measuring moisture conditions in the field. KEYWORDS cold in-place recycling (CIR), time domain reflectometer (TDR), moisture content, moisture loss index

Development of a Simulation-Based Approach for Cold In-Place Recycled Pavement Moisture-Content Prediction Using Ground-Penetrating Radar

“…The most common method is sampling materials from the field and drying samples in a forced-draft oven until consistent weights are obtained ( 7 , 10 ). Aside from sampling, Woods et al and Kim et al used capacitance moisture sensors (CMOS) embedded at various depths of pavement layer ( 6 ) and a time-domain reflectometer (TDR) ( 12 ) to monitor moisture content before overlay in several project sites in Iowa. However, both CMOS and TDR are mostly used to predict moisture content in soft solid materials rather than an AC mixture ( 13 , 14 ).…”

“…In addition, difficulties may occur during the installation and maintenance of these sensors. For example, during the TDR measurement, the stiff pavement layer must be drilled to create small holes for the insertion of TDR probes, especially on cool days ( 12 ). Furthermore, these methods are localized, time-consuming, and expensive to be implemented in field projects, making them unreliable options.…”