Extended Finite Element Method (XFEM) models are prepared to observe the progression of an existing crack in the AC pavements under thermal fatigue load only. 2-D XFEM models are developed using the commercial software ABAQUS. The XFEM model consists of four layers, and it includes 263 mm Asphalt Concrete (AC), 150 mm base, 200 mm subbase, and subgrade layers. Creep tests were performed on the AC samples at -15 °C, 0 °C, and 18 °C and the temperature-dependent viscoelastic material properties regarding Prony series were determined and used in the XFEM. The Coefficient of Thermal Expansion (CTE) and Contraction (CTC) of AC were also identified in the laboratory and the field. The pavement temperature data was collected using the temperature probes installed in the 1-40 pavement section, and one-day temperature variation in the pavement is recorded, and that data is repeated as a thermal fatigue load in the XFEM model. Three XFEM models are developed considering one 50 mm existing crack but with three different cracks spacing such as two cracks are spaced within 1220 mm, 12200 mm, and 61000 mm. The results show that the existing crack propagation stops at approximately 5 thermal cycles for the cracks that have 1220 mm crack spacing, 6 thermal cycles for 12200 mm crack spacing and 8 thermal cycles for 61000 mm crack spacing. The crack length propagated from the existing 50 mm length to 81% for 1200 mm crack spacing, 106% for 12200 mm crack spacing and 118% for 61000 mm crack spacing.
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