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  • Wang, Han  (4)
  • Mobility and traffic research  (4)
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  • Mobility and traffic research  (4)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 462-473
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 462-473
    Abstract: Real-time stiffness monitoring of unbound aggregate layers using embedded field sensors is crucial for advanced airport pavement design and management. This paper describes research findings on monitoring base layer stiffness characteristics for airport pavements using an embedded bender element (BE) field sensor, inductive coil sensors, and pressure cells. A full-scale pavement test section was constructed at the Federal Aviation Administration (FAA)’s National Airport Pavement Test Facility (NAPTF). A BE field sensor, inductive coil sensor pairs, and pressure cells were installed in the unbound aggregate base to evaluate the layer stiffness, applied load stress, and deformation characteristics. A triple dual tandem gear loading module applied 58,000 lb per wheel to the tested section with a wander pattern consisting of 66 passes arranged in nine lateral wander positions. Dynamic responses of coil sensors and pressure cells were collected during the traffic test, whereas BE signals were collected after completing each wander pattern. Laboratory repeated load triaxial tests with BE instrumentation were also conducted to establish a correlation for converting BE field sensor readings to layer modulus properties. The in situ modulus characteristics of the aggregate base layer were evaluated during full-scale testing using two methods: shear wave velocities from a BE field sensor, and strain and stress measurements from coil sensors and pressure cells. The moduli estimated using both approaches fell into typical ranges of crushed aggregate bases and were highly comparable. The moduli from the dynamic sensor measurements clearly showed the effect of vehicle wander on aggregate base layer measured responses.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 10 ( 2023-10), p. 339-350
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 10 ( 2023-10), p. 339-350
    Abstract: Geogrids are commonly used in paved and unpaved roadways to stabilize base and subbase layers by laterally restraining movements of unbound aggregates under applied wheel loading, often referred to as interlocking. The geogrid-aggregate interlock is a function of the match between the geogrid aperture size and geometry and the grain size and shape characteristics of the stabilized aggregates. Open-graded coarse aggregates (OGA) are commonly used as an alternative to dense-graded materials in permeable base/subbase applications as well as in railway ballast to facilitate drainage. This paper describes an experimental study recently conducted to investigate the repeated load-deformation behavior of a geogrid-stabilized OGA material in large-scale triaxial testing. Two multi-axial geogrids with the same aperture patterns but different aperture sizes were tested. The aperture patterns include different sizes of hexagonal, trapezoidal, and triangular openings. The multi-axial geogrid with the larger apertures better matched the OGA material properties to provide a reduction in permanent deformation in the test specimen. The improved interlocking and the related local stiffness enhancement were successfully quantified using embedded shear wave transducers termed bender elements. To stabilize aggregates with relatively uniform grain sizes, for example, AASHTO No. 57 stone studied here and railroad ballast, the ratio between the aperture size and a representative particle size (i.e., D 90 ) served as a good indicator of the effectiveness of the geogrid. The findings of this experimental study therefore provided valuable information on the governing properties and mechanisms that play a role in geogrid-aggregate interaction with multi-axial geogrids.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 2022
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2676, No. 8 ( 2022-08), p. 386-397
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2676, No. 8 ( 2022-08), p. 386-397
    Abstract: This paper presents a case study for constructing aggregate subgrade improvement (ASI) layers using quarry by-product aggregates (QBA)—a quarry mix of large primary crushed rocks (PCR) and sand-sized quarry fines. The construction took place at Larry Power Road in Bourbonnais Township in Kankakee County, Illinois, where the Illinois Department of Transportation (IDOT) placed two QBA mixes for performance evaluation. The first mix (QBA_M1) consisted of 45% quarry by-products (QB) and 55% railroad ballast-sized PCR. The second mix (QBA_M2) consisted of 31% QB and 69% PCR. Two conventional ASI sections with only PCR were also constructed. All sections consisted of a 229 mm (9 in.) QBA/PCR layer topped with a 76 mm (3 in.) thick dense-graded capping layer. Laboratory studies preceded the construction to recommend optimum QB percentages for the QBA materials and construction practice. The quality and uniformity of the construction was ensured through field testing using dynamic cone penetrometer (DCP), lightweight deflectometer (LWD), and falling weight deflectometer (FWD). The segregation potential of the QBA mixes was monitored by visual inspection, aggregate stockpile sampling, and image analysis techniques. Short-term field evaluation of the constructed QBA layers, particularly QBA_M2 with 31% QB, showed no evidence of major segregation. The QBA ASI layers had slightly lower but comparable strength and stiffness profiles to the conventional ASI sections. The use of QBA materials in ASI was therefore field validated in this case study as a sustainable construction practice to provide stable pavement foundation layers.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2403378-9
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 428-438
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 428-438
    Abstract: The progressive degradation of railway ballast over time increases the degree of ballast fouling and poses significant drainability concerns leading to frequent maintenance activities. To avoid such issues, an effective and continuous characterization of the physical properties of the ballast layer is deemed necessary. This paper introduces the combined use of a bender element (BE) piezoelectric field sensor and a PANDA ® dynamic cone penetrometer for periodic evaluations of ballast condition over the traffic use. To simulate various levels of ballast degradation, box tests were conducted using a dolomitic ballast material compacted in a laboratory-sized testbed with fouling indices ranging from zero to 39%. BE sensor pairs were embedded in the ballast layer to calculate the small strain modulus behavior of the ballast assessed through shear wave velocity measurements under different confinement conditions. Strength profiles of the ballast at different fouling levels were also measured using the PANDA ® penetrometer. Experimental findings from both test methods indicate the existence of a dense state of ballast linked to a certain fouling index that maximized stiffness and strength characteristics of the tested ballast in dry condition. Accordingly, the potential use of BE field sensors embedded within in-service ballasted track coupled with periodic penetration testing can be a viable approach to evaluate ballast layer degradation. Various void packing conditions associated with ballast fouling levels can be linked to important ballast layer modulus and strength behavior. Further, such smart sensing of ballasted track behavior can provide long-term performance monitoring solutions for ballast cleaning and maintenance scheduling.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
    Location Call Number Limitation Availability
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