Comparative fracture resistance assessment of rubber-modified asphalt mortar based on meso-and macro-mechanical analysis

ABSTRACTThis study investigates the effects of ground tire rubber (GTR) on the cracking resistance of asphalt mortar from different analysis scales. Furthermore, the effectiveness of different fracture test methods was compared for GTR-modified asphalt mortar, including the indirect tensile cracking test (IDEAL-CT), disk-shaped compact tension test (DCT) and Illinois flexibility index test (I-FIT). To achieve this, a mesoscopic fracture test based on the SEM-Servo Plus device was proposed firstly to obtain the micro-parameters of constitutive models in discrete-element modelling (DEM). A unified fracture modelling procedure that can avoid any interference factors was carried out for comparative fracture analysis. Results from the tests and simulations show that rubber filler plays a positive role in enhancing the fracture properties of the asphalt mortar. The fracture energy measured by IDEAL-CT is almost 5–6 times of the DC(T) test and 1.5–2 times of the I-FIT test. It is not an inherent attribute of material and can only be regarded as a relative index for fracture resistance evaluation. The FI and CTindex obtained from the I-FIT and IDEAL-CT test show a weak correlation of fracture resistance, especially when comparatively evaluating the GTR-modified asphalt mortar with minor difference in filler content.KEYWORDS: Discrete element methodground tire rubberfracture mechanismcohesive zone modellingdisk-shaped compact tension test AcknowledgementsThe results and opinions presented are those of the authors and do not necessarily reflect any of the supporting parties.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by the National Natural Science Foundation of China [grant number NO.52208427]; Natural Science Foundation of Jiangsu Province [grant number BK20220844]; Open Research Fund of Hubei Key Laboratory of Theory and Application of Advanced Material Mechanics [grant number TAM202201]; Open Research Fund of Highway Engineering Key Laboratory of Sichuan Province [grant number HEKLSP2022-02]; Shuangchuang Program of Jiangsu Province [grant number JSSCBS20220094].