Issue 43

M. Fakhri et alii, Frattura ed Integrità Strutturale, 43 (2018) 113-132; DOI: 10.3221/IGF-ESIS.43.09 120 Figure 5 : Effect of aggregate type on fracture energy at 5°C under pure mode I loading condition. Figure 6 : Effect of aggregate type on fracture energy at 25°C under pure mode I loading condition. The effect of air void content on fracture energy under pure mode I loading condition In Fig. 7 and Fig. 8 the fracture test results obtained for mode I have been shown to investigate the effect of air void on the fracture energy of tested HMA mixtures under different loading rates and at two temperature levels of 5°C and 25°C. At 5°C, the highest fracture energy of investigated asphalt mixtures containing different air void percentages was achieved under loading rate of 5 mm/min. Besides, in high loading rates, air void content alteration had negligible effect on fracture energy of AC. At 25°C, fracture energy enhances by increasing the loading rate for mixtures with different air voids. The difference between the values of fracture energy at 25°C is less for asphalt mixtures with low percentage of air void (i.e. 3%), since the matrix tends to behave more homogenously and the loading rate effect on the fracture behavior of AC is less, than the mixture containing greater air void percentages (i.e. 5 and 7%).