Specimen type effect on measured low‐temperature fracture toughness of asphalt concrete

Abstract

Mode I fracture resistance of two asphalt mixtures (control and modified with low‐density polyethylene [LDPE] as binder additive) was studied experimentally and theoretically. The fracture toughness experiments were conducted on edge notch disc bend, edge notch disc compression and semi‐circular bend configurations under two loading rates and two low temperatures. The fracture resistance was increased by increasing the loading rate, reducing the test temperature and adding the LDPE additive. A discrepancy due to the influence of specimen geometry and its loading type was also observed on the measured critical stress intensity factors, demonstrating the effect of specimen type on mode I fracture behaviour. By considering the maximum normal strain value as constant material property and taking into account the effect of T‐stress, the fracture toughness value for any of the investigated mode I samples was estimated in terms of the fracture results of the other specimens.

Contribution of Interface Fracture Mechanism on Fracture Propagation Trajectory of Heterogeneous Asphalt Composites

“…Afterwards, some experimental testing methods and test samples including the edge cracked rectangular beam specimen subjected to four-point bend loading and the semi-circular bend (SCB) specimen were employed by Molennar et al [11,12] for investigating the mode I fracture of the asphalt mixtures. Other test configurations such as the modified indirect tensile disc (MITD) specimen [13], disc-shape compact-tension specimen [14], single edge notch beam (SENB) subjected to three-point bend [9,15], wedge splitting disc (WSD) [16], edge notch disc bend (ENDB) [17][18][19][20][21][22][23][24], edge notch disc diametral compression (ENDC) [25][26][27], center cracked Brazilian disc subjected to diametral compression [28], semi-circular bend (SCB) specimen [29][30][31][32][33][34], and hollow disc (or ring shape) specimen containing center crack and loaded diametrically [35] are some of the test configurations employed in the literature for investigating the fracture resistance of asphalt mixtures. Any of these test samples are suitable for simulating and conducting specific modes of fracture.…”

Heterogeneity effect on fracture parameters of a multilayer asphalt pavement structure containing a top‐down crack and subjected to moving traffic loading

“…Different test samples and testing methods such as SCB, center cracked Brazilian disc, edge notch disc bend, and four‐point bend specimens have been used in previous asphalt fracture toughness studies for conducting the mixed mode tensile‐shear fracture experiments 57–77 . On the other hand, some well‐known theories such as the maximum tangential stress or strain criteria and maximum tangential strain energy density were employed earlier for theoretical predictions of the experimental test results obtained from the asphalt mixtures at low temperature conditions 78–82 . The same fracture models can be employed for predicting the fracture load and fracture trajectory of real cracked asphalt pavement structures.…”

Pure mode I and pure mode II fracture resistance of modified hot mix asphalt at low and intermediate temperatures

“…Cracking as structural distress is one of the most important distresses in different types of pavements, especially in cold regions. By changing the service temperature in asphalt concrete layers, bitumen's viscoelastic behavior may lead to different behaviors for asphalt mixtures; particularly at higher temperatures, bitumen behaves like a viscous material, and cracking is more likely to occur at intermediate temperatures 1–4 . Asphalt pavement failures such as fatigue cracking (due to loading), thermal cracking, longitudinal cracking, and reflective cracking (due to temperature changes) are directly related to the fracture properties of asphalt materials used in the pavement layers 5–7 .…”