Assessment of resistance to crack propagation of asphalt mixtures using two parts digital image correlation

Abstract

The use of recycled aggregates in the manufacturing of asphalt concrete is becoming increasingly widespread. This requires special attention to characterize their performance in terms of durability to reduce major maintenance and rehabilitation expenditures. To achieve this, it is necessary to use effective and easy-to-implement test procedures to observe and estimate the various damage and cracking processes that often lead to the structural failure of materials. Many studies have shown that the estimation of cracking energy depends on the extent of damage and cracking processes. In this context, the method of estimating the crack propagation path and the accompanying damage strongly influence the calculated value of the fracture energy. This can lead to an overestimation or underestimation of the material’s performance. Based on these considerations, our aim is to introduce a new approach for improving the estimation of cracking processes to assess resistance to crack propagation. A three-point bending test was conducted on recycled bituminous concrete samples with a single notch at two distinct temperatures, −5 °C and 10 °C. The extent of the cracking process and damage was estimated using 2PDIC, a two-part digital image correlation method. The parametric analysis of the measurements obtained by 2PDIC reveals that defining the pseudo-strain threshold enables the observation of different amplitudes and levels of strain associated with the various processes that accompany the cracking test. The results obtained for the two temperatures considered demonstrate a significant change in cracking energy, which is often overestimated and depends on the crack propagation path and the granular arrangement of the material through which the crack passes. The measurements obtained using 2PDIC also demonstrate the greater tortuosity of the crack propagation path at higher temperatures, which results in a reduction of the estimated cracking energy derived from more simplistic approaches.