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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Concrete Ties for Transit Track-An Update
Author(s): A. N. Hanna
Publication: Special Publication
Appears on pages(s): 343-360
Keywords: ballast; electrical properties; fasteners; insulation;
performance; prestressed concrete; production methods; railroad
ties; rapid transit railways; reinforced concrete; specifications;
Abstract:Today, at least ten transit properties in the United States and Canada use pretensioned monoblock or reinforced two-block concrete ties. Pretensioned monoblock concrete ties have been manufactured by the long-line method. Reinforced two-block ties have been manufactured in individual forms using the "instant demolding" method. High strength concrete and pre-stressing tendons, and reinforcing and structural steel conform-ing to current standards have been specified for the production of concrete ties. Quality control programs that address material properties, production operations, and tolerances are required to assure consistency in quality and performance. In a concrete tie rack, the fastening system maintains gage, maintains alignment, restrains longitudinal rail movement, provides resilience, and assures electrical insulation. The ballast provides supporting strength and resistance to the loads imposed on track, resil-ience, stability, and drainage capabilities. The ability of the ties and fasteners to provide their intended functions is evalu-ated by laboratory tests. The tests evaluate tie strength at rail seat and at tie center, the bond between the concrete and prestressing tendons or reinforcing steel, the ability of the fastener to provide adequate longitudinal and lateral restraint and to resist uplift forces, the serviceability of the tie and fastener components under service-simulated loads, and the ability of the tie-fastener system to provide adequate electrical resistance and impedance. A concrete tie track provides techni-cal, economical, and environmental advantages by using improved fastening systems and eliminating components with high mainten-ance requirements. A concrete tie track would generally yield a lower life-cycle cost than a wood tie track and provide better service operation and increased safety.
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