Article 1 — Description
Furnish, store, and handle post -tensioning materials , and perform post -tensioning of cast -in-place and precast structural units .
Article 2 — Materials
Furnish materials that meet requirements of the following unless specified otherwise. PTI Guide Specification for Grouted Post -Tensioning (PTI/ASBI M50) PTI Specification for Grouting of Post -Tensioned Structures (PTI M55).
2.1 Prestressing Steel . Furnish prestressing steel strand conforming to one of the following types:
seven- wire steel strand meeting DMS -4500 , “Steel Strand, Uncoated Seven- Wire Low -Relaxation for Prestressed Concrete,” or Grade 150, high- strength, coarse thread bars meeting ASTM A722.
2.2 Post -Tensioning System . Furnish a pos t-tensioning system following the minimum requirements for
Protection Level 2 (PL -2), or higher protection level when shown on the plans, in accordance with PTI/ASBI M50. Prequalify post -tensioning systems using tests on complete tendons for compliance with the requirements of PTI/ASBI M50. The following exceptions apply . The embedded parts of the anchorage are not required to be galvanized or epoxy coated, unless otherwise shown on the plans . Provide pre- packaged grouts in accordance with DMS -4670 , “Grouts for Post -Tensioning.” Do not use grouts that exceed the manufacturers’ recommended shelf life or 6 mo. after date of manufacture, whichever is less. Provide unbonded single- strand tendons in accordance with PTI M10.2-00, Specification for Unbonded Single Strand Tendons .
Article 3 — Equipment
3.1 Stressing Equipment . Provide hydraulic jacks, pressure gauges, and other stressing equipment that meets
PTI/ASBI M50.
3.2 Grouting Equipment . Provide grout mixing, testing, and pumping equipment that meets PTI M55.
Article 4 — Construction
Item 420, “Concrete Substructures ,” and Item 422, “Concrete Superstructures, ” will govern for cast -in-place construction. Item 424, “Precast Concrete Structural Members (Fabrication),” will govern for precast concrete units or members.
4.1 Qualifications of Personnel . Perform all work for post -tensioning, including duct and hardware installation,
strand insertion, and tendon or bar stressing, under the direct supervision of an individual certified as a PTI 586 Level 2 Bonded PT Field Specialist. Perform all grouting operations under the direct supervision of an individual who has received a Grouting Technician Certification from ASBI.
4.2 Require d Submittals . Submit information in accordance with this Section for post -tensioned elements, in
addition to forming and falsework plans required by Item 420 and Item 424. Include all necessary construction information in these submittals for cast -in-place and precast construction including, but not limited to the information required in this Section.
4.2.1 Design Calculations. Provide design procedures, coefficients, allowable stresses, tendon spacing, and
clearances in accordance with the AASHTO LRFD Bridge Des ign Specifications and PTI/ASBI M50 unless otherwise shown on the plans. Submit enough calculations to support the proposed system and method of post-tensioning, including friction loss diagrams. When the required jacking force for a particular type of tendon, duct, and configuration is shown on the plans, design calculations are not required except to adjust for conditions different from those shown on the plans.
4.2.2 Post -Tensioning Details . Provide drawings with details that meet the requirements of PTI/ASBI M50 and
this Item.
4.2.3 Grouting Plan. Submit for approval written grouting procedures at least 4 weeks before the start of the
element’s construction. Include items required by PTI M55. At minimum include: type, quantity, and brand of material used, and their corresponding material properties; type of equipment needed, including backup equipment; type and location of all inlets, outlets, and intermediate vents; types and sizes of grout hoses and connections; grouting operations procedures, including duct cleani ng, mixing, pumping, direction of grouting, and sequence of the use of inlets and outlets; mitigation plan if blockages occur; and the names of the persons in charge and all field personnel who will be performing the grouting operations and their pertinent experience. Include the names of people responsible for post -tensioning installation and grouting operations, with the foreman of each grouting crew certified as a PTI Level 2 Bonded PT Field Specialist and ASBI Certified Grouting Technician.
4.2.4 Stressing Safety Plan . Provide a plan to protect the public, workers, and Department personnel in and
around the vicinity where post -tensioning operations are occurring. Submit for approval a detailed safety plan that identifies potential risk associated with post-tensioning operations, including but not limited to: tendon alignment, temporary shoring, ram operations, and strand anchorage.
4.3 Packaging, Storing, and Handling of Post -Tensioning Components . Package, store, and handle
post-tensioning steel, grout, duct, and other accessories in accordance with PTI/ASBI M50 and PTI M55 unless otherwise specified. Acceptance and rejection criteria for strand will follow PTI/ASBI M50 and PTI M55. The following exceptions apply. Grout storage onsite will be limited to 30 days unless approved by the Engineer in advance of material delivery. 587 Install grout caps and ensure vents are always closed so that water and other contaminants cannot enter the duct before strand installation. Do not flush ducts at any time.
4.4 Duct and Pre stressing Steel Installation for Post- Tensioning. Follow PTI/ASBI M50 for duct and
prestressing steel installation procedures and requirements unless otherwise specified. Verify that concrete strength requirements shown on the plans are met for stressing and staged loading of post -tensioned structural elements . Before stressing, furnish certified copies of load calibration curves on all jacks and gauge systems to be used in the work. Stress the tendons within 7 days of installing the strand in the ducts unless otherwise approved in advance. Follow the tensioning procedure noted in the approved post -tensioning details. The Contractor is to provide documentation of elongation measurements after tendons have been stressed but before cutting strands. After the elongations have been approved, immediately cut off the tendon strand tails.
4.5 Grouting. Grout in accordance with PTI M55.
Provide grout mock -ups as shown on the plans. Grout within 14 days of tendon stressing unless otherwise specified or approved. Obtain approval to extend the grouting time before stressing tendons. Do not allow the grout temperature to exceed 85°F during mixing and pumping. Do not grout when the ambient temperature is below 35°F. Field- test the grout in accordance with Table 1 during grout installation. Perform field- testing by trained personnel at the Contractor’s expense while witnessed by the Engineer. Pump at the lowest pressure possible that will maintain a continuous flow of grout . Table 1 Requirements for Field -Testing of Grout Test Requirement Frequency Schupak pressure bleed test (ASTM C1741) , % Max 0 at 100 psi 1 per day Fluidity test ( Tex-437-A, Method 2)
a.Immediately after mixing, sec.
b.30 min. after mixing with 30 -sec. remix, sec. Min 5, Max 20 Max 20 2 every 2 hr. 2 Min per day Compressive strength test (3 ” × 6” cylinders) 3,000 at 7 days 5,000 at 28 days 1 per day Mud balance test ( Tex-130-E, Part II)1,2 Per PTI M55 2 per day 1. Take one sample from the mixer and one sample from the farthest duct outlet. 2. Verify wet density is within the range established by the manufacturer.
Article 5 — Measurement
This Item will be measured by each post -tensioning element or member. An element or member is defined by one of the following individual components: post-tensioned cap, post-tensioned column, post-tensioned bent, or other elements shown on the plans. The post -tensioning may extend into other elements subsidiary to the main element being post -tensioned. 588 6. PAYMENT The work performed and materials furnished in accordance with this Item and measured as provided under “Measurement” will be paid for at the unit price bid for “PT” for the member type shown on the plans. This price is full compensation for submittals, mock -ups, prestressing steel, post -tensioning, ducts, grout fitti ngs, grout, end anchorages, bearing plates, equipment, labor, materials, tools, and incidentals. Materials furnished for testing will not be paid for directly. Post-tensioning of precast members, tensioned at a fabrication plant, will not be paid for direc tly, but will be subsidiary to pertinent Items.
Source: Texas Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges, 2024 Edition. Pages 595–598 of 1,034.