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Page 64
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2021. Repair and Maintenance of Post-Tensioned Concrete Bridges. Washington, DC: The National Academies Press. doi: 10.17226/26172.
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Page 64
Page 65
Suggested Citation:"Glossary." National Academies of Sciences, Engineering, and Medicine. 2021. Repair and Maintenance of Post-Tensioned Concrete Bridges. Washington, DC: The National Academies Press. doi: 10.17226/26172.
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Page 65

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64 Admixture: A material (usually a liquid or powder) that is a component of cementitious grout and is added immediately before or during mixing. Aggregate: Granular material, such as sand, gravel, crushed stone, iron blast-furnace slag, or recycled aggregates including crushed hydraulic cement concrete, used with a cementing medium to form concrete or mortar. Anchor: A steel element either cast into concrete or post-installed into a hardened concrete member and used to transmit applied loads to the concrete. Also called an anchorage. Anchorage zone: In post-tensioned members, the region of the member through which the concentrated prestressing force is transferred to concrete and distributed more uniformly across the section; its extent is equal to the largest dimension of the cross-section. For anchorage devices located away from the end of a member, the anchorage zone includes the disturbed regions ahead of and behind the anchorage device. Bleed: The autogenous flow of mixing water within, or its emergence from, freshly placed grout; caused by the settlement of the solid materials within the mass and filtering action of strands, wires, and bars. Bridge: Any structure spanning not less than 20 ft that forms part of a roadway. In this docu- ment, generally part of a highway. Cementitious materials: Materials having cementing value if used in grout, mortar, or concrete, including portland cement, blended hydraulic cements, expansive cement, fly ash, raw or calcined natural pozzolan, slag cement, and silica fume, but excluding alternative cements. Connection: Region of a structure that joins two or more members; a connection also refers to a region that joins members, of which one or more is precast. Duct: Material forming a conduit to accommodate the prestressing steel installation and to provide an annular space for the filler material (i.e., grout or flexible filler), which protects the prestressing steel. Durability: Ability of a structure or member to resist deterioration that impairs performance or limits service life in the environment for which it was designed. Flexible filler: Non-cementitious filler material. Its use results in an unbonded tendon, lacking stress-strain compatibility with the primary concrete member. Flexible fillers may include petroleum-derived microcrystalline waxes, greases, or polymer gels. Grout: A mixture of cementitious materials and water, with or without mineral additives, admixtures, or fine aggregate. In PT applications, it is proportioned to produce a pumpable consistency without segregation of the constituents and injected into the duct after post- tensioning to fill the space around the tendon. Glossary

Glossary 65   Inlet: Tubing or duct used for injection of grout into the duct. Joint: Portion of a structure common to intersecting members. Outlet: Tubing or duct used to allow the escape of air, water, grout, and bleed water from the duct. Post-tensioning: A method of prestressing in which the tendons are tensioned after the concrete has reached a specified strength. Prestressing element: The tension element of a post-tensioning tendon, which is elongated and anchored to provide the necessary permanent prestressing force. Prestressing steel: The steel element of a post-tensioning tendon, which is elongated and anchored to provide the necessary permanent prestressing force. Quality assurance: Actions taken to ensure that what is being done and what is being provided are in accordance with the specifications and applicable standards. Quality control: Actions taken by the contractor to provide control over what is being done and what is being provided to ensure that the specifications and applicable standards of good practice for the work are being followed. Sheathing: General term for the duct material surrounding the prestressing element to provide corrosion protection or conduit for installation. Span: Distance between supports. Strand, seven-wire: Strand (most commonly conforming to ASTM A416 in PT applications) consisting of seven wires having a center wire enclosed tightly by six helically placed outer wires with a uniform pitch of not less than 12 and not more than 16 times the nominal diameter of the strand. Stress corrosion cracking: Brittle cracking process caused by the conjoint action of tensile stress and a corrodent. Tendon: A single or group of prestressing elements and their anchorage assemblies that impart the prestress force to a structural member or the ground. Also included are ducts, grouting attachments, and grout. Tendon, bonded: Tendon in which prestressed reinforcement is continuously bonded to the concrete through grouting of ducts embedded within the concrete cross-section. Tendon, external: A tendon totally or partially external to the member concrete cross-section, or inside a box section, and attached at the anchor device and deviation points. Tendon, internal: A tendon totally internal to the member concrete cross-section. When filled with cementitious filler material, such as grout, stress-strain compatibility is maintained, and the material of the cross-section is considered entirely homogeneous. Tendon, unbonded: Tendon in which prestressed reinforcement is prevented from bonding to the concrete. The prestressing force is permanently transferred to the concrete at the tendon ends by the anchorages only.

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Repair and Maintenance of Post-Tensioned Concrete Bridges Get This Book
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The use of post-tensioning in concrete structures has allowed for the construction of economical long-span bridges. However, very limited information is available to guide bridge owners on how to maintain existing structures or, more specifically, to repair degraded post-tensioned structures.

The TRB National Cooperative Highway Research Program's NCHRP Synthesis 562: Repair and Maintenance of Post-Tensioned Concrete Bridges gathers information on the practices used by bridge owners to repair and maintain post-tensioned bridges and facilitates knowledge transfer across state departments of transportation (DOTs), aiding bridge owners in the identification of repair practices that are working and that will extend the useful life of the bridges.

Supplemental materials to the report include appendices containing the survey and the survey responses.

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