Abstract
Cold in-place recycling (CIR) of asphalt pavements is a process that has successfully been used for many years. The use of CIR for rehabilitation offers many advantages over traditional overlays due to its excellent resistance to reflective cracking and its environmentally friendly impacts. Despite the good performance and positive sustainability aspects of CIR, the structural contribution of the CIR base layer has not been well defined. In this research, CIR mixtures were designed with different asphalt emulsions. The mixtures were then subjected to dynamic modulus, repeated load triaxial, and flexural beam fatigue testing over a range of temperature and loading conditions. The performance test data generated were then used to develop CIR rutting and fatigue performance models used in the mechanistic analysis of flexible pavements. The technique used to develop the performance models leveraged the fact that the rutting and fatigue models for individual CIR mixtures were all within the 95 percent confidence interval of each other. A mechanistic analysis was conducted using the 3D-Move Mechanistic Analysis model. With the laboratory-developed performance models, the structural layer coefficient for the CIR base layer were developed for use in the 1993 AASHTO Guide for the Design of Pavement Structures. This analysis led to the determination of an average structural coefficient of the CIR base layer of 0.25.
Highlights
Santos, José Neves and MohammadCold in-place recycling (CIR) of asphalt pavements is a process that has successfully been used for many years [1]
The objective of this study was to evaluate the structural contribution of the CIR layer within typical Nevada flexible pavements
Flexural beam fatigue, and repeated load triaxial tests were successfully used to assess the behavior of CIR mixtures in a mechanistic analysis based on models developed from the test results
Summary
Cold in-place recycling (CIR) of asphalt pavements is a process that has successfully been used for many years [1]. CIR is a major pavement rehabilitation treatment, consisting of milling the top 50–75 mm of the asphalt concrete (AC) layer followed by in-place cold mixing with asphalt emulsion and stabilizing agents (i.e., Portland cement or hydrated lime), and compacted using traditional methods [2]. Traditional rehabilitation techniques for flexible pavements include overlays and mill/overlay Both of these techniques suffer from the reflection of cracks that exist in the old pavement which limit their service life. CIR is a relatively quick rehabilitation process with machine production rates increasing. It is a long-term cost-effective treatment with reduced maintenance costs. When excess Portland cement has been used, CIR has exhibited shrinkage cracking resulting in reflective cracking
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