Assessment of Fracture Parameters to Predict Field Cracking Performance of Cold In-Place Recycling Mixtures

Abstract

Highway agencies are commonly faced with the challenging task of rehabilitating highly distressed asphalt concrete pavements. Cold in-place recycling (CIR) has gained popularity as a cost-effective and sustainable way of dealing with such a challenge. CIR performance success is typically defined on the basis of the CIR resistance to transverse cracking over time. CIR resistance to fracture is not a design criterion that is accounted for in the material evaluation or design phase of a CIR project. The ability of fracture parameters to predict field cracking performance of CIR mixtures was assessed on the basis of nine sites in three states consisting of past rehabilitation projects, 2 to 5 years old, that involved CIR and new asphalt concrete overlay mixtures. The evaluation of the sites was based on transverse cracking performance evaluation as longitudinal cracking was determined to be affected by construction techniques rather than materials properties. A test temperature selection process at which to perform ASTM D7313-07 and measure fracture energy–related parameters was proposed to account for the effect of project location and mixture depth. Fracture energy successfully differentiated between satisfactory and poor performance of CIR surface mixtures. The findings of this research identified a test and evaluation process that opened the door for design- and performance-related specifications on the basis of minimum fracture energy thresholds related to observed transverse cracking spacing occurrences. The fracture energy offers a tool to mixture designers interested in optimizing CIR mixtures for cracking resistance.