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Austin, TX, United States

Hong F.,Materials and Pavements Section | Chen D.-H.,Materials and Pavements Section | Mikhail M.M.,Materials and Pavements Section
Transportation Research Record | Year: 2010

Recycled asphalt pavement (RAP) has been increasingly used in flexible pavement construction and rehabilitation. Laboratory and in-place evaluation of the performance of RAP and hot-mix asphalt (HMA) produced with RAP is necessary to the successful use of RAP. Extensive research work has been reported with a focus on laboratory tests of RAP materials. But comprehensive evaluation of the long-term in-service pavement performance with RAP is still at its early stage. In this study, the Texas Specific Pavement Studies Category 5 experimental sections from the Long-Term Pavement Performance program provide an opportunity to investigate the in situ performance of HMA with RAP based on about 16 years of data. In the underlying flexible pavement rehabilitation project, the factorial design includes surface preparation, material, and thickness factors. In particular, a relatively high percentage of RAP, with a content of 35% by weight, was adopted in the asphalt overlay. An in-depth investigation of the pavement performance involving two typical distresses, ride quality and transverse cracking and rutting, is conducted. Compared with sections without RAP (HMA with virgin materials), sections with RAP demonstrated higher cracking amount, less rut depth, and similar roughness change over time. The overall evaluation revealed that a well-designed mix with 35% RAP could perform as satisfactorily as that produced with virgin materials to meet the in-service performance requirement.

Huang Y.,Materials and Pavements Section | Copenhaver T.,Materials and Pavements Section | Hempel P.,Materials and Pavements Section | Mikhail M.,Materials and Pavements Section
Transportation Research Record | Year: 2013

Pavement texture is an important indicator of road serviceability. Pavement texture is directly linked to pavement and tire skid resistance and to traffic safety for the public. Therefore, most transportation agencies require texture data for their pavement management information systems. Current methods for measuring pavement texture that use high-speed distance sensors or three-dimensional line scan devices have shown limitations for data stability. Problems caused by vehicle vibration, bad data from optical sensors, and, most important, speed dependency related to the sensor sampling time or exposure time either make the texture results unreliable or reveal noticeable errors. The influence of speed on network-level texture data collection was studied, and a high-speed, high-precision three-dimensional texture system was developed. The experiment confirmed that improper selection of a sensor with large exposure time would result in speed dependency on measured texture data. Because the system developed in the study adopted a very small exposure time for each sampling, it could produce accurate texture data that are largely independent of vehicle speed.

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