Application of laboratory asphalt cracking tests to cold in-place recycled mixtures

Cold in-place recycling (CIR) is an asphalt pavement rehabilitation technology which is rapidly gaining popularity. This technique consists in milling the top 75–100 mm of an existing asphalt pavement, mixing the crushed material with a recycling agent, and reusing it to repave the roadway. Hence, there is a need to identify laboratory tests for developing CIR mixtures with improved resistance to cracking. This study investigates the applicability of semi-circular bend (SCB) and disk-shaped compact tension (DCT) tests to CIR mixtures. Tests were performed on five similar laboratory and field prepared mixtures. Since the CIR mixtures were relatively softer and more brittle than typical hot mix asphalt, minor modifications to the testing parameters and data analysis approach were found necessary. Fracture energies computed from SCB and DCT data resulted in being statistically similar and detected considerable differences among the five mixtures. Overall, both fracture tests showed good repeatability and potential applications in mix design engineering and optimisation of CIR mixtures, quality control and field validation usages.