چكيده به لاتين
These days the use of recycled asphalt due to the proper impact on the performance of asphalt mixtures is expanding.
Preventing the formation and growth of cracks at low and medium temperatures is one of the important issues in recycled asphalt mixtures.
Mostly fracture mechanics principles are used to analyze cracking in the recycled asphalt mixtures in tensile modes. However, the recycled asphalt mixtures are placed during their operation life in different loading modes such as tensile mode, in-plane shear mode, out-plane shear mode, and also tensile-shear modes inside and outside the plane.
Given that, yet no research has been done on the loading modes of out-plane shear and tensile-shear modes on the fracture mechanisms of recycled asphalt mixtures. The purpose of this work is to study the fracture mechanisms of recycled asphalt mixtures under the mentioned modes at low temperatures. For this, the fracture resistance of recycled asphalt mixtures in monotonic loading conditions using a cracked edge sample with a circular cross-section under the bending has been evaluated.
To this purpose, usual asphalt mixtures with bitumen adhesives PG 64-22, PG 58-22 and PG 52-28 and asphalt mixtures containing 25, 40, and 55 percent of recycled asphalt particle with bitumen adhesives PG 58-22 and PG 52-28 is made. After determining the critical fracture load using the equations of fracture mechanics, the fracture toughness values in different loading modes for usual and recycled asphalt mixtures were calculated and the results were compared with each other. The critical fracture mode was also determined for each of the asphalt mixtures.
Based on the results of this study, fracture resistance is a function of the characteristics of asphalt mixtures and the effect of each of the mentioned variables on the fracture life of asphalt mixtures can vary depending on the load mode.
