Issue 43

M. Fakhri et alii, Frattura ed Integrità Strutturale, 43 (2018) 113-132; DOI: 10.3221/IGF-ESIS.43.09 126 Figure 16 : The effect of aggregate type on fracture energy at 25°C under mixed mode I/II loading condition. The effect of air void content on fracture energy under mixed mode I/II loading condition The trend of fracture energy change by increasing air void content under four loading rates at 5°C is presented in Fig. 17. Fracture energy reaches its maximum value under loading rate of 10 mm/min for all three asphalt mixtures with different air void content (3, 5 and 7%). Comparing test results under different loading mode conditions, we have realized that fracture energy of AC is higher under mixed mode I/II loading condition comparing to pure modes I and II in all specimens with different air void contents at the same temperature. Furthermore, the average value of fracture energy of AC specimens with air void of 5% for different loading rates is the highest comparing to other air void contents (3 and 7%). Similar to two other studied modes (pure mode I and pure mode II), the trend of mixed mode fracture energy change of AC specimens with different void contents, is incremental for increasing loading rates at intermediate temperature as shown in Fig. 18. For mild climate conditions (i.e. 25°C), the most appropriate condition for AC to resist fracture is high loading rates (i.e. 50mm/min) applying to asphalt mixtures with air void content of 5%. Figure 17 : The effect of air void content on fracture energy at 5°C under mixed mode I/II loading condition.