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Type of Steel Length of Tendon Type of Duct µ <br /> Tendon L(m) <br /> Wire or Strand 0 to less than 183 Rigid or semi- 0.15 <br /> rigid <br /> galvanized- <br /> sheet <br /> alvanizedsheet metal <br /> 183 to less than 275 0.20 <br /> 275 to less than 366 0.25 <br /> Greater than or 0.25* <br /> equal to 366 <br /> Wire or Strand All Plastic 0.23 <br /> All Rigid Steel 0.25* <br /> Pi es <br /> High Strength All Rigid or semi- 0.30 <br /> Bar rigid <br /> galvanized <br /> sheet metal <br /> *With the use of lubrication <br /> The thirteenth and fourteenth paragraphs in Section 50-1.08, "Prestressing," of the Standard Specifications are amended <br /> to read: <br /> • Prestressing steel in pretensioned members shall not be cut or released until the concrete in the member has attained <br /> a compressive strength of not less than the value shown on the plans or 28 MPa, whichever is greater. In addition to these <br /> concrete strength requirements,when epoxy-coated prestressing steel strand is used,the steel shall not be cut or released until <br /> the temperature of the concrete surrounding the strand is less than 65°C,and falling. <br /> • When ordered by the Engineer,prestressing steel strands in pretensioned members, if tensioned individually, shall <br /> be checked by the Contractor for loss of prestress not more than 48 hours prior to placing concrete for the members. The <br /> method and equipment for checking the loss of prestress shall be subject to approval by the Engineer. Strands which show a <br /> loss of prestress in excess of 3 percent shall be retensioned to the original computed jacking stress. <br /> Item 2 of the eleventh paragraph in Section 50-1.08,"Prestressing,"of the Standard Specifications is amended to read: <br /> 2. When the concrete is designated by class or cementitious material content,either the concrete compressive strength <br /> shall have reached the strength shown on the plans at the time of stressing or at least 28 days shall have elapsed <br /> since the last concrete to be prestressed has been placed,whichever occurs first. <br /> The second and third paragraphs in Section 50-1.09, 'Bonding and Grouting," of the Standard Specifications are <br /> amended to read: <br /> • Grout shall consist of cement and water and may contain an admixture if approved by the Engineer. <br /> • Cement shall conform to the provisions in Section 90-2.01A,"Cement." <br /> ^ The fifth paragraph in Section 50-1.10,"Samples for Testing,"of the Standard Specifications is amended to read: <br /> • The following samples of materials and tendons, selected by the Engineer from the prestressing steel at the plant or <br /> jobsite,shall be furnished by the Contractor to the Engineer well in advance of anticipated use: <br /> A. For wire or bars, one 2-m long sample and for strand, one 1.5-m long sample, of each size shall be furnished for <br /> each heat or reel. <br /> B. For epoxy-coated strand,one 1.5-m long sample of uncoated strand of each size shall be furnished for each reel. <br /> C. If the prestressing tendon is a bar,one 2-m long sample shall be furnished and in addition,if couplers are to be used <br /> with the bar, two 1.25-m long samples of bar, equipped with one coupler and fabricated to fit the coupler, shall be <br /> furnished. <br /> The first paragraph in Section 50-1.11,"Payment,"of the Standard Specifications is amended to read: <br /> Contract No. 10-OM7104 <br /> 28 <br />