Effects of Recycled Materials on Long-Term Performance of Cold In-Place Recycled Asphalt Roads

With a limited maintenance budget and unprecedented construction cost increases, many owner/agencies in the United States are beginning to rehabilitate existing distressed pavements. Cold in-place recycling (CIR) provides an economical rehabilitation method and has been widely used in the past 20 years. However, recycled roads have experienced inconsistent performance and that has hindered the application of CIR. The objective of this paper is to study the cause and effect relationships between factors, such as traffic loading, support condition, and aged engineering properties of the CIR materials, and pavement performance. Twenty-four roads in Iowa were examined through field and lab tests. Statistical analyzes show that, within the range of data in this study, better performance was observed on CIR roads with lower CIR modulus value and/or higher air voids.     

Thermal Probe Technology for Buildings: Transition from Laboratory to Field Measurements

This paper reports the results of an investigation into the transfer of thermal probe measurement technology from laboratory use to actual buildings in order to undertake the in situ determination of thermal material properties. The imperative reasons for using in situ measurements are (1) the impact of moisture content on thermal properties; (2) the possible wide range of variation of properties across most materials used in construction; and (3) the lack of data for new and innovative materials. Thermal probe technology offers the prospect of taking building specific data, addressing these issues. Based on commercially available thermal probes a portable measurement kit and accompanying measurement procedure have been developed. Three case study buildings, each having different materials, have been studied to ascertain whether or not the technique can be transferred to relatively uncontrolled environments and remain capable of achieving a precision that is similar to an ASTM standard that can be related to thermal conductivity measurements of building materials. The results show that this is indeed the case, and that the use of thermal probe technology may yield thermal properties that vary significantly from the laboratory values currently used in building thermal engineering calculations.