503Prestressed Concrete and Precast Members

503.01.01 General. This work consists of furnishing and installing prestressing and post -tensioning systems

and other items necessary for the particular prestressing system used, including but not limited to ducts, anchorage assemblies , and local zone reinforcement in precast concrete members or cast -in-place concrete members. This work also consists of furnishing and placing either precast reinforced concrete members or precast prestressed concrete members as indicated on the plans. Where reference is made herein to the “pretensioning method,” the prestressing steel strands or bars are assumed to be tensioned in a casting bed prior to placing concrete in the forms. Where referenc e is made herein to the “post -tensioning method,” the prestressing steel strands or bars are assumed to be tensioned in ducts after the concrete has been placed and has obtained the specified strength. Furnish all components of a post -tensioning system fr om a single supplier. Prestressing steel can be obtained from any supplier as long as all prestressing steel in a tendon is from one supplier. Furnish and place complete precast prestressed concrete and precast concrete members including all concrete, pre stressing steel and items appurtenant to the pretensioning method used, reinforcing steel , and incidental materials in connection therewith. Install prestressing steel, which may be strands or bars, in the concrete. Stress to a predetermined load. Where post-tensioning is used, grout ducts to fill all voids and install protection at end anchorages.

503.01.02 P recast Plant Certification. Produce all precast prestressed concrete members in a fabrication

plant certified by the Precast/Prestressed Concrete Institute ( PCI), unless otherwise approved in writing. The fabrication plant shall have a B3 or B4 Certification as required for the members being produced, unless otherwise approved in writing. Portable pretensioning beds will not be allowed. Submit a co py of the fabrication plant’s PCI Certification and most recent PCI plant audit report before or along with the first submittal of shop drawings.

503.01.03 Personnel Certification s. Provide project personnel meeting the requirements of this Subsection.

For p recast concrete plant f acility Quality Control (QC) , provide an on -site production manager, an on -site Facility Manager for QC, a plant engineer, and on -site QC inspectors/technicians to provide complete QC inspections and testing. Ensure the Facility Manager for QC has at least five years of related experience and a current Precast/Prestressed Institute (PCI) QC personnel Level III certification. Ensure that the QC inspector/technician has current PCI QC Technician/Inspector Level II certification. Submit copies of personnel certifications and qualifications for approval with the precast member shop drawings. Perform all post -tensioning field operations under the direct supervision of a technician certified as a Level 2 Bonded PT Field Specialist thro ugh the Post -Tensioning Institute (PTI). Provide the name of the technician and furnish proof of certification with the prestressing working drawings. Provide an individual certified as either a Certified Grouting Technician through the American Segmental Bridge Institute (ASBI) or a PTI Level 2 Bonded PT Field Specialist to supervise, inspect, and document the entire grouting operation. Provide close observation and control of all grouting operations by the certified technician. Have the certified technic ian on -site at any time when grouting is taking place. Provide the name of the grouting technician and furnish proof of certification with the Grouting Operations Plan. MATERIALS

503.02.01 General. Material shall conform to the following Sections and Sub section:

Portland Cement Concrete ................................ ................................ ................................ ................................ ..................... Section 501 Concrete Structures ................................ ................................ ................................ ................................ ............................... Section 502 Reinforcing Steel ................................ ................................ ................................ ................................ ................................ .... Section 505 Prestressing Steel ................................ ................................ ................................ ................................ ................... Subsection 713.03.0 3 503 PRESTRESSED CONCRETE AND PRECAST MEMBERS 248 503.02.02 Tendon Grout. Provide a commercial, prepackaged, tendon grout for grouting post-tensioning ducts. Deliver grout in moisture proof plastic lined or coated bags. Provide bags with manufacturer’s labels showing brand name, intended application, date of manufacture, expiration date, lot number, and mixing and pumping instructions. Use grout within six months of the manufacture date. Tendon grout shall conform to the requirements for a Class C grout, as defined by the Post -Tensioning Institute (PTI) Specification for Grouting of Post -Tensioned Structures and shall meet the vertical rise requirements for the project tendons. Tendon grout shall not contain aluminum powder, gas generating components that produce hydrogen gas, carbon dioxide, or oxygen, expansive admixtures, or admixtures containing chloride. Submit certified mill test reports for the tendon grout upon request. Tendon grouts will be approved based on prequalification testing. Perform testing by an independent certified testing facility. Test tendon grout at normal laboratory temperatures of 18 to 25 °C (65 to 78 °F) unl ess otherwise specified by the referenced test method. Re-qualify tendon grout for any changes made to either the source or type of all ingredients of the tendon grout. Testing conducted for other state transportation agencies may be accepted as prequalif ication testing provided the test requirements herein are satisfied. For findings and evaluations of other state Departments of Transportation see the AASHTO Prod uct Evaluation Listing Service. Submit evidence that the grout manufacturer has an on -going q uality control program for the tendon grout it produces. Evidence may include, but is not limited to, quality control data sheets, or recent test results for the proposed tendon grout. Test results shall be dated within one year of the intended grouting of the tendons. Tendon grout shall conform to the following: TEST TEST METHOD REQUIREMENT Strength ASTM C942 21 MPa (3,000 psi) minimum @ 7 days 35 MPa (5,000 psi) minimum @ 28 days Initial Set ASTM C953 3 hr minimum , 12 hr m aximum Permeability ASTM C1202 as m odified by Section 4.4.3 of PTI* Less than 2,500 coulombs after 6 hours using 30 volts on 28 day grout Volume Change ASTM C1090 Vertical height change between 0.0% and + 0.1% @ 24 hours Vertical height change of + 0.2% maximum @ 28 days Fluidity For thixotropic grouts, ASTM C939 as modified by Section 4.4.5.2 of PTI* For non -thixotropic grouts, ASTM C939 After either test above, let sample stand for 30 minutes without further agitation , remix for 30 seconds , then test immediately Efflux time between 5 and 30 seconds for a 1 liter discharge immediately after mixing Efflux time between 11 and 30 seconds immediately after mixing For thixotropic grout, e fflux time of 30 seconds maximum for a 1 liter discharge For non -thixotropic grout, e fflux time of 30 seconds maximum Wick Bleed Wick Induced Bleed ASTM C940 as modified by Section C4.4.6.1 of PTI* 0.0% maximum at 3 hours @ 20 °C (70 °F) Pressure Bleed Schupack Pressure Bleed (Gelman Pressure) in accordance with Appendix C of PTI* 4% max at 20 psi with vertical rise between 0 to 0.6 m (0 to 2 ft) 2% max at 30 psi with vertical rise between 0.6 to 1.8 m (2 to 6 ft) 0% max at 50 psi with vertical rise between 1.8 to 30.5 m (6 to 100 ft) Chloride Ions ASTM C1152 Less than 0.08% by mass of cementitious material Fine Aggregate ASTM C136 99% passing the 300 µm (No. 50) sieve * PTI Specifications for Grouting of Post -Tensioned Structures. * Use ASTM C117 procedure modified to use a No. 50 sieve. Determine the percent passing the No. 50 sieve after washing the sieve. Water for mixing grout shall have less than 500 ppm of chloride ions and no organic materials. Water with a pH less than 4.5 or greater than 8.5 and a resistivity less than 500 ohm•cm will be tested according to AASHTO T26. Any indication of unsoundness, marked change in time of setting, or a reduction of more than 10% in strength from results obtained with grout mixtures containing the water of satisfactory quality shall be sufficient cause for rejection of the water under tests.

503.02.03 N onshrink Grout . Provide grout that is a non -metallic, non -metal oxidizing, and non -gas-liberating

flowable fluid containing natural aggregate, Portland cement and additives and requiring only the a ddition of water. Provide a minimum of 385 kg of cement per cubic meter (650 lb of cement per cubic yard) nonshrink grout. Provide premeasured and prepackaged grout by the manufacturer, that is suitable for baseplate and foundation grouting. Show no aggreg ate segregation or settlement at fluid consistency at specified times or temperatures. Grout shall pass through a flow cone with continuous flow one hour after mixing. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 249 Provide nonshrink grout conforming to the requirements of ASTM C1107, and the following additional requirements: PROPERTY TEST METHOD REQUIREMENT Shrinkage ASTM C827 0.0% Expansion ASTM C827 0.0% minimum, 4.0% maximum Fluid Consistency USACE CRD -C611/ASTM C939 20-30 seconds at 4 -38 °C (40 -100 °F) 1-day Compressive Strength ASTM C109 24.1 MPa (3500 psi) minimum 3-day Compressive Strength ASTM C109 31.0 MPa (4500 psi) minimum 28-day Compressive Strength ASTM C109 51.7 MPa (7500 psi) minimum Chloride Content ASTM C1152 0.24 kg/m3 (0.40 lb/yd3) maximum Grout shall have a minimum initial set time of 4 hours and minimum final set time of 6 hours at 21 °C (70 °F). Prior to use , store materials in suitable moisture resistant containers in a cool and dry environment. Label containers clearly with manufacturer’s recommendations, limitations and cautions. Do not use broken or open packages. Provide grout with low levels of chlorides as specified above and free from other corrosion -causing chemicals. Design nonshrink grout for an air content of 4 to 6 percent. Mix, place , and cure grout in accordance with the manufacturer’s requirements, these specifications , and as approved. Provid e mix water conforming to the requirements of Subsection 503.02.02. Use cold water in hot weather conditions to maintain the mixed grout temperature from 7 to 32 °C (45 to 90 °F). Use a quantity of water to be b lended with the dry component within the limits recommended by the manufacturer. Use the least amount of water required to produce a flowable or fluid batter as required for the application, and as approved. Submit for approval, specific printed manufactu rer’s product data including recommended preparation , placement and curing methods for each nonshrink grout applicat ion. Nonshrink properties shall not be based on gas or gypsum expansion. CONSTRUCTION

503.03.01 General. Perform prestressing by either (a) pretensioning methods, or (b) post -tensioning methods.

If the plans show details for only one particular method, the use of the alternate method will be allowed only upon approval. If use of the alternate method is appro ved, submit complete details and design calculations for the alternate and for any other necessary modifications to the member for approval . Details and design calculations for approved alternate methods shall be stamped by a n engineer who is r egistered as a Civil or Structural Engineer in the State of Nevada. Do not commence work until details and design calculations are approved in writing. Submit working drawings according to Subsection 105.02 , giving complete details and substantiating calculations o f the method, materials, and equipment proposed for use in the construction, prestressing, and/or erection operations. Outline in such details the method of prestressing, and include the arrangement of the prestressing steel and mild steel reinforcement in the member (including grillage reinforcing designated in the Standard Plans) , any additions or rearrangement of reinforcing steel, any revision in concrete dimensions from that shown on the plans, and working stresses. Submit complete, independent working drawings for each structure, working drawings shall not refer to drawings submitted for other structures. For the pretensioning method, show on the shop drawings a sequence for cutting or releasing the prestressing steel. Include details and calculations for lifting embedments and lifting locations; methods of handling, storage, and transport . Provide a sequence of casting indicating when forms will be stripped, strands cut, and beams removed from the bed. Indicate the decision process for each action in the casting sequence. Do not start fabrication of any precast prestressed concrete member until shop drawings have been approved, written notice of the start of fabrication has been provided, and a pre -fabrication meeting has been completed . For the post -tensioning method also include on the working drawings the specifications and details of anchoring devices and distribution plates or assemblies, calculated stresses in the anchorages and distribution plates, type of post-tensioning enclosures, sequence of stressing prestressing steel, pressure grouting materials and equipment, including all inlets, outlets, drains, permanent grout caps, direction of grouting and a method of detensioning the prestressing steel should it become necessary to do so before grou ting takes place. The working drawings shall 503 PRESTRESSED CONCRETE AND PRECAST MEMBERS 250 also include results of post -tensioning anchorage system prequalification testing according to Subsection 503.03.04 and a grouting operations plan according to Subsection 503.03.07 . Do not use or install prestr essing steel in the work until the prestressing steel has been sampled, tested and approved for use. When requested, s ubmit drawings of forms proposed for the precast concrete members according to Subsection 105.02 . Show in such drawings the complete details of the type of forms proposed for providing any indicated openings and proposed method of supporting and anchoring such forms. If electing to prestress precast concrete members and a prestressed option is not shown on the plans, design the members as precast prestressed members and the design calculations and drawings according to Subsection

105.02 Design calculations and drawings shall be stamped by an engineer who is registered as a Civil or Structural

Engineer in the State of Nevada. Do not com mence work until details and design calculations are approved in writing. Give notice in writing 14 days in advance of performing prestressing operations.

503.03.02 Protection of Materials. Store and protect all prestressing materials in a weatherproof e nclosure

until time of use. Protect all prestressing steel against physical damage, rust, and other results of corrosion at all times from manufacture to grouting or encasing in concrete. Prestressing steel that has sustained physical damage will be reject ed. The development of visible rust or other results of corrosi on will be cause for rejection. Package prestressing steel in containers or shipping forms for the protection of the steel against physical damage and corrosion during shipping and storage. Pl ace a corrosion inhibitor which prevents rust or other results of corrosion in the package or form, or incorporate in a corrosion inhibitor carrier type packaging material, or when permitted , apply directly to the steel. The corrosion inhibitor shall have no deleterious effect on the steel or concrete or bond strength of steel to concrete. Immediately replace or restore packaging or forms damaged from any cause to original condition. Clearly mark the shipping package or form with a statement that the packa ge contains high -strength prestressing steel, the care to be used in handling, and the type, kind and amount of corrosion inhibitor used, including the date when placed, safety orders and instruction for use. Do not weld reinforcing or prestressing steel. Any weldments to reinforcing or prestressing steel shall be subject to rejection. Replace any reinforcing or prestressing steel rejected by the Engineer. Make no welds or grounds for welding equipment on the forms or on the steel in the member after the prestressing steel has been installed. If prestressing steel for pretensioning is placed in the stressing bed and exposed to the elements for more than 36 hours before encasement in concrete, take acceptable m easures to protect said steel from contamination or corrosion. If prestressing steel for post -tensioning is installed in members prior to the placement of concrete, such as strand in flat ducts , continuously protect prestressing steel against rust or othe r corrosion, until grouted, by means of a corrosion inhibitor placed in the ducts or applied to the steel in the duct . Provide a vapor phase corrosion inhibitor formulated for use in protecting prestressing steel in ungrouted tendons that does not contain silicates, phosphates, nitrates or heavy metals, that provides up to 24 months of continuous protection using a monomolecular inhibiting layer and which does not affect the physical properties of the concrete or grout. Submit brand name, MSDS, product instructions and evidence of past successful use on other projects for approval. When prestressing steel for post -tensioning is installed in the ducts after completion of concrete curing, and if stressing and grouting are completed within 10 days after the pr otective packaging has been opened, rust which may form during said 10 days will not be cause for rejection of the steel. The use of a corrosion inhibitor in the duct following installation of the prestressing steel within the above 10 days, will not be re quired except when requested because of adverse weather conditions. Prestressing steel installed as above but not grouted within 10 days shall be subject to all the requirements in this Subsection pertaining to corrosion protection and rejection due to rust. When steam curing is used, do not install prestressing steel for post -tensioning until the steam curing is completed. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 251 Ship ducts for prestressing steel in bundles which are covered during shipping and storage. Protect ducts against crushing, excessive bending, dirt contamination and corrosive elements during transportation, storage and handling. Do not remove covering supplied with the ducts until the ducts are incorporated into the bridge component. Store ducts on a raised platform and completely cove red to prevent contamination. If necessary, wash ducts before use to remove contamination. Use water for flushing ducts containing either quick lime (calcium oxide) or slaked lime (calcium hydroxide) in the amount of 12 g/L (0.10 lb/gal). Use oil free compressed air to blow out ducts. Store tendon grout in waterproof enclosures maintaining temperatures within the range recommended by the manufacturer . Do not open packaging until time of mixing. Bags or bulk containers that are damaged or previously opened will be rejected.

503.03.03 Forms. Do not deposit concrete in the forms until after inspection of reinforcement, anchorages,

ducts, inlet and outlet pipes, embedments , and/or prestressing steel. Deposit concrete in forms that have a minimum temperatu re of 5 °C (41 °F) and are within 17 °C (30 °F) of the temperature of the concrete at the time of placement. Vibrate the concrete internally or externally, or both, as required to consolidate the concrete. Vibrate with care and in such a manner to not dis place reinforcement, ducts, anchorages, embedments and/or prestressing steel. Construct forms for interior cells or holes in the members of a material that will resist breakage or deformation during the placing of concrete and will not materially increase the mass of the member. “Lost forms,” left in place in interior cells, shall not exceed 575 N/m2 (12 lb/ft2) of supported deck area. Provide access through forms to locations where operations for duct pressure testing and grouting operations will be performed. Side forms for prestressed members may be removed the day after placing concrete therein, provided satisfactory arrangements are made for curing and protecting the concrete. Remove all side forms before releasing pretensioned prestressing steel and before tensioning post -tensioned prestressing steel. Remove side forms of precast pretensioned members after the concrete has reached the compressive strength shown on the plans or a minimum of 21 MPa (3,000 psi) . Remove side forms prior to cooling wh en accelerated curing methods are used. For precast members, provide holes for anchor bars, and for diaphragm dowels which pass through the member, openings for connection rods, recesses for grout, and any other holes and recesses as necessary in the memb ers according to the details shown on the plans or the approved working drawings . Where diaphragm dowels do not pass through the member, the dowels may be anchored in the member by embedment in the concrete or by means of an approved threaded insert. Lifting anchors may be installed in precast members provided any portion of the anchor extending beyond the precast member is removed after the member is placed.

503.03.04 Anchorages and Distribution. Secure all post -tensioned prestressing steel at the ends b y means

of approved permanent type anchoring devices. Post-tensioning anchorage systems will be approved based on prequalification testing. Conduct prequalification testing by an independent testing laboratory which certifies that the complete tendon anch orage system meets the requirements of Subsection 10.3.2.3 of the AASHTO LRFD Bridge Construction Specifications . Testing conducted for other state transportation agencies may be accepted as prequalification testing. Submit documentation of anchorage system prequalification with the working drawings for approval. Include the following information in the submittal:

503.03.05 Ducts. Provide and accurately place duct enclosures for prestressing steel of mortar -tight rigid

galvanized ferrous metal. Ensure that all connectors, connections , and components of post -tensioning system hardware are rated for the minimum pressure requirements herein. Ducts for prestressi ng steel made up of a single wire, bar or strand, shall have a minimum inside diameter 13 mm (1/2 in.) larger than the diameter of the wire, bar, strand, or couplers to be used. For tendons made up of a plurality of wires, bars, or strands, the duct area s hall be at least 2.5 times the gross area of the pre stressing steel. Use rigid ducts with either welded or interlocked seams. Galvanizing of the welded seam will not be required. Provide ducts of sufficient strength to maintain their correct alignment dur ing placing of concrete. Use positive metallic connections between sections which do not result in angle changes of the joints. Use waterproof tape at the connections. Bend ducts without crimping or flattening. Transition couplings connecting ducts to anch oring devices need not be galvanized. Construct tendons using a minimum number of duct splices. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 253 Accurately align ducts and position at the locations shown on the plans and according to the approved shop drawings or as otherwise directed. The center of gravity of the prestressing force shall not vary from girder to girder unless noted in the plans or approved shop drawings. Securely fasten all internal ducts in position as necessary to maintain accurate duct placement during concreting and at regular intervals not exceeding 610 mm (24 in.) for round galvanized duct and 300 mm (12 in.) for flat ducts to prevent movement, displacement or damage from concrete placement and consolidation operations. Show the method and spacing of duct supports on the shop drawings. Use mandrels as needed to maintain duct alignment and shape. Place ducts providing a smooth and continuous alignment with no lips, kinks , or dents. Provide smooth transitions in duct joints without any kinks. Do not exceed angle changes by more t han ± 3 degrees in any direction. Install post -tensioning ducts to within the following tolerances: Application Vertical Position mm (in.) Lateral Position mm (in.) Horizontal tendons in slabs or in slab regions of larger members ± 6 (1/4) ± 13 (1/2) Longitudinal draped super -structure tendons in webs: Tendon over supports or in middle third of span Tendon in middle half of web depth ± 6 (1/4) ± 13 (1/2) ± 6 (1/4) ± 6 (1/4) Longitudinal, generally horizontal, superstructure tendons in top or bottom of member ± 6 (1/4) ± 6 (/4) Horizontal tendons in substructures and foundations ± 13 (1/2) ± 13 (1/2) Application Longitudinal Position mm (in.) Transverse Position mm (in.) Vertical tendons in webs ± 25 (1) ± 6 (1/4) Vertical tendons in pier shafts ± 13 (1/2) ± 6 (1/4) Construct ends of tendon anchorage entrance and exit angles to within ± 3 degrees of the angle shown on the approved shop drawings when measured in any direction. Provide smooth transitions without any kinks or deviations in the align ment. Locate anchorages within ± 6 mm (1/4 in.) of desired position laterally and ± 25 mm (1 in.) along the tendon except that minimum cover requirements shall be maintained. Position anchorage confinement reinforcing steel as shown on the approved shop drawings in the form of spirals, multiple U shaped bars or links, to be properly centered around the duct and to start within 13 mm (1/2 in.) of the back of the main anchor plate. In the event of conflicts between the reinforcing steel and post -tensioning duct, the position of the post-tensioning duct shall prevail with the reinforcing steel adjusted locally as approved. Carefully check and repair all ducts as necessary before placing concrete. Use methods to place and consolidate concrete which will not displace or damage post -tensioning ducts, anchorage assemblies, splices and connections, reinforcement , or other embedments. Fabricate duct splices to prevent duct kinks during concrete placement. Use mandrels as needed to maintain duct alignment and shape . Plug all tendons except preloaded ducts at the anchorages with plumbing type expanding compression plugs at the time the anchorages are attached to the forms and before concrete placement. Maintain plugs in place until after curing is completed and the ducts are ready for pressure testing prior to strand installation. Place grout inlets and outlets at locations as shown on the plans and working drawings. At a minimum, place grout inlets and outlets in the following positions:

503.03.06 Prestressing. Furnish and install prestressing steel and t ension by means of hydraulic jacks so that

the force in the prestressing steel is not less than the value shown on the plans. For post -tensioning of cast -in-place members, distribute the prestressing steel so that the force in each girder stem is equal as required by the plans, or as provided herein. For box girders with more than 2 girder stems, the prestressing force may vary u p to 5% from the theoretical required force per girder stem provided the required total force in the superstructure is obtained and the force is distributed symmetrically about the centerline of the cross section. Distribute the prestressing steel so that the center of gravity of the prestressing tendon path in each girder stem matches the path shown on the plans. Do not install strand into ducts until the curing of the deck is complete, unless flat ducts require installation prior to concrete placement . Push or pull p restress ing strands through the ducts to make up a tendon using methods which will not snag on any lips or joints in the ducts. When strands are pushed, round their ends or fit them with a smooth protective cap. Do not use mechanical devices to rotate strand during the installation into the duct. Alternatively, strands may be assembled to form the tendon and pulled through the duct using a special steel wire sock or other device attached to the end. Do not weld strand together . Round the end of the pre -assembled tendon for smooth passage through the duct. Cut strands using an abrasive saw or equal. Flame cutting is not allowed. Suspend or support strand during loading so that it does not come in contact with the ground. Where strands are pull ed in and must be assembled outside the tendon, provide raised platforms, tarps or other means to prevent dirt and dust contamination of the strands. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 255 Do not post -tension cast -in-place and precast concrete until at least 10 days after the last concrete has been placed in the member and until the compressive strength of concrete has reached the strength required on the plans and shop drawings. Compressive strength shall be determined by cylinder tests. Conduct all stressing operations in the presence of t he Engineer. After stressing, do not cut exposed strand until the elongations are approved. Do not cut or release prestressing steel in any pretensioned member until the concrete has attained the minimum compressive strength value specified for releasing of the steel. Tension prestressing steel to an initial force of 20% of the jacking force , unless shown otherwise on the plans or approved shop drawings . After initial tensioning, apply final jacking force to prestressing steel and measure elongation. Do not allow the temporary tensile stress (jacking stress) to exceed 80% of the specified minimum ultimate tensile strength of the prestressing steel. Do not overstress tendons to achieve the expected elongation. Anchor prestressing steel at stresses (init ial stress) that will result in the ultimate retention of permanent stresses or forces of not less than those shown on the plans . Do not allow the initial stress at the anchorage s to exceed 70% of the specified minimum ultimate tensile strength of the pres tressing steel. Limit the initial stress in the prestressing steel at all locations along the tendon except at the anchorages to 74% of the specified ultimate tensile strength. Working force and working stress will be considered as the force and stress re maining in the prestressing steel after all losses, including creep and shrinkage of concrete, elastic compression of concrete, creep of steel, losses in post-tensioned prestressing steel due to sequence of stressing, friction and take up of anchorages, an d all other losses peculiar to the method or system of prestressing have taken place or have been provided for. The loss in stress in post -tensioned or pretensioned prestressing steel due to creep and shrinkage of concrete, creep of steel, sequence of str essing, and elastic compression of concrete shall be as indicated on the plans. Determine losses p articular to the chosen method or system of prestressing such as sequence of stressing or friction and take up of anchorage and include in submittal of substa ntiating calculations for review. Prepare substantiating calculations in accordance with the bridge design specifications and design parameters as indicated on the plans. Compensate for the loss of prestress in pretensioned members due to the temperature of prestressing steel being appreciably lower than the estimated temperature of the concrete by increasing the calculated elongation. Take into account the loss of prestress in the total forces in the prestressing steel, but do not exceed a jacking stress of 80% of the specified minimum ultimate tensile strength of the prestressing steel. Only use jacking equipment furnished by the supplier of post -tensioning system (tendons, hardware, anchorages, etc.). If power seating st ressing equipment is used to reduce losses due to anchor set, submit certified test results showing the amount of seating loss that can be consistently achieved. Equip each jack used to stress tendons with either a pressure gage or a load cell for determi ning the jacking stress. Provide pressure gage, if used, with an accurately reading dial at least 150 mm (6 in.) in diameter. Calibrate each jack and its gage as a unit with the cylinder extension in the approximate position that it will be at final jackin g force, and accompany with a certified calibration chart. Provide calibrated load cell, if used, with an indicator by means of which the prestressing force in the tendon may be determined. Do not use the lower 10% of the manufacturer’s rated capacity of t he load cell in determining the jacking stress. Calibrate each jack and its gage s as a unit. The calibration shall consist of three test cycles with the cylinder extension of the jack in various positions including the approximate cylinder position expect ed at the final jacking force [i.e. 50 mm (2 in.), 100 mm (4 in.), 200 mm (8 in.), etc strokes ]. At each pressure increment, average the forces from each test cycle to obtain an average force. Perform the calibration with the equipment (jack, pump, hoses, etc.) setup in the same configuration that is intended to be used at the job site. The post -tensioning supplier or an independent laboratory shall perform initial calibration of jacks and gage s. Use load cells calibrated within the past 12 months to calibr ate stressing equipment. For each jack and gage unit used on the project, furnish certified calibration charts and curves prior to stressing. For extended duration projects, furnish updated calibration charts and curves every 6 months, or as requested. Supply documentation denoting the load cells calibration date and traceability to NIST (National Institute of Standards and Technology) along with the jack/gage calibration. 503 PRESTRESSED CONCRETE AND PRECAST MEMBERS 256 Any hydraulic jack repair, such as replacing seals or changing the length of the hyd raulic lines, is cause for recalibration using a load cell. Provide a calibrated load cell, if used, with an indicator by means of which the prestressing force in the tendon may be determined. The certified calibration charts for the hydraulic jacks, pre ssure gage s, or load cells used for tensioning prestressing steel may be checked before and during tensioning operations with State -furnished load cells. Provide sufficient labor, equipment, and material to install and support the load cells at the prestre ssing tendons and to remove the load cells after the checking is complete, as ordered. The checking operations will be conducted by the Engineer. Except as noted on the plans or the approved shop drawings, tension post-tensioning tendons from both ends. Apply t he required force at one end and subsequently at the other end. Where one end stressing is shown on the plans or approved shop drawings , and the stressing end is not indicated , tension one-half of the tendons from one end of the member and the other half from the opposite end. For construction in stages where some tendons are required to be stressed before others, install and stress in accordance with the plans or approved shop drawings or as otherwis e approved. Conduct the tensioning process so that tension being applied and the elongation of the prestressing steel may be measured at all times. Mark the strand or provide a positive attachment to the strand so that slippage or uneven jack pull can be easily identified. Record gage pressures and elongations at all times while tensioning and submit for approval. Measure elongations to the nearest 1.5 mm (1/16 in.). Stop stressing operations if the measured elongation at total tendon force is not within ± 5% of the calculated theoretical elongation or if similar tendons differ by more than ± 4%. Determine cause and do not restart stressing operations until corrective measures are approved. Do not exceed the total tendon force to achieve the calculated theoretical elongation. When ordered, check prestressing steel in pretensioned members, if tensioned individually, for loss of prestress not more than 3 hours before placing concrete. The method and equipment for checking the loss of prestress will be subjec t to approval. Re-tension all tendons to the original intended jacking force which show a loss of prestress in excess of 3%. Multi -strand post -tensioning tendons having wire or strand failures, by breaking or slippage during stressing, may be accepted at the discretion of the Engineer under the following conditions:

503.03.0 7 Bonding and Grouting. Bond post -tensioned prestressing steel by completely filling the entire void

space in the duct with grout. Complete grouting each tendon wit hin 14 days of placing the strand or bar into the duct. Fully tension all post -tensioning within the structure prior to any grouting operation. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 257 When shown on the plans, debond pre -tensioned prestressing steel by encasing strands in plastic sheathing along the entire debonded length, and seal the ends with waterproof tape. Split plastic sheathing may be used provided the seam is sufficiently sealed with waterproof tape to prohibit concrete infiltration. Do not use sheathing that will permanently alter the p hysical or chemical properties of the surrounding concrete. Full-length debonding of straight strands will only be allowed if designated on the approved working drawings . Full-length debonding, when permitted, shall be symmetrical about the vertical centerline of the beam and limited to 10% of the total number of straight strands or 6 straight strands, whichever is less. Do not debond draped strands full length.

503.02.03 for filling and repairin g anchorage pour -backs, grout inlets and outlets, keyways and access holes.

Mechanically clean and abrasive blast clean the surface of concrete against which nonshrink grout is to be placed until clean aggregate is exposed. Abrasive blast clean the contac t surfaces of existing concrete and any exposed reinforcing steel, as necessary, to remove all rust, paint, grease, asphalt or other foreign materials. Take necessary steps to not damage reinforcing steel coatings. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 261 Remove ends of grout vents a minimum of 75 mm (3 in.) below the top of the top slab and a minimum of 50 mm (2 in.) from the bottom surface of all bottom slabs or vertical surfaces after grouting has been completed. Top slab grout vents extended to the edge of deck to exit within the barrier area may be removed flush with the surface of the deck. Use cored holes or formed blockouts with 25 mm (1 in.) minimum deep vertical edges at all sides. Do not use blockouts larger than 125 mm (5 in.) in largest horizontal dimension. Do not sawcut past corners on square blockouts to obtain the required vertical surfaces. Following surface preparation, coat surfaces with Type II epoxy conforming to Subsection 728.03.02. Apply bonding agent to saturated surface dry concrete and in accordance with the manufacturer’s recommendations . Immediately prior to placing the nonshrink grout, re -clean all surfaces by air blasting, or by other approved means, as necessary to remove any debris which have accumulated during construction or after abrasive blast clean ing. Place nonshrink grout when surface temperature of the areas to be covered is between 7 and 32 °C (45 and 90 °F). Methods proposed to heat said surfaces are subject to approval by the Engineer. Place nonshrin k grout when the contact surface is saturated surface -dry. Cure n onshrink grout after initial set by continual wetting with water for a period of 48 hours. After 48 hours of wet curing , spray the nonshrink grout with two coats of curing compound as specif ied in Section 501. Provide a flow cone and cube molds with restraining plates for onsite evaluation of nonshrink grout . Make three 50 mm by 50 mm (2 in. by 2 in.) cubes for each 0.5 m3 (0.67 yd3) of nonshrink grout used. Provide restraining caps for the cube molds in accordance with USACE CRD-C621. Store cubes at 21 °C (70 °F). Nonshrink grout cubes shall test equal to or greater than the specified minimum 28 -day strength. Submit test reports for cubes for approval. Do not use nonshrink grout that is caked, lumpy, or shows any signs of deterioration. Nonshrink grout will be rejected if the grout does not achieve the design fluidity or consistency when mixed according to the manufacturer’s recommendations. Nonshrink grout used in pourbacks exceeding 0.028 m3 (1 ft3) in volume may be extended by adding graded, dust-free, hard, 12.5 mm ( 1/2 in.) diameter rounded aggregate supplied by the grout manufacturer. Vibrate nonshrink grout extended with aggregate. Do n ot use calcareous aggregate made from limestone. Use mix proportions in conformance with manufacturer's written recommendations. Grout extended with aggregate shall meet the specified strength requirements. Prior to deck grooving, coat the repaired access holes, block -outs and an area extending 150 mm (6 in .) outside the perimeter of the repair with an approved crack sealant specified in Section 646 . Apply and remove excess material as per manufacturer’s instructions.

503.03.08 Curing Precast Member s. Cure precast members according to Subsection 501.03.0 8 or by

accelerated curing. Inadequate curing facilities or lack of attention to proper curing of precast members will be cause for rejection of the precast member. When the curing compound method is used, abrasive blast clean portions of precast members upon which concrete will be cast later.

503.03.09 Handling, Transportin g, Storage, and Erection of Precast Members. During handling, transport,

storage, and erection, keep each precast girder vertical and upright to prevent twisting, racking, or other distortion that would result in cracking or damage to the precast member. U se equipment and erection methods that will not damage precast girders. Repair or replace damaged girders as determined by the Engineer. Repair all damaged girders by approved methods and materials. Lift precast girders only at their ends by approved lifti ng devices. Provide lateral bracing to prevent tipping or buckling. Do not remove precast members from forms sooner than six hours after casting and not until the concrete strength is sufficient to avoid structural damage. For AASHTO Type V, Type VI, and Bulb-T Beams, do not remove the forms supporting the top flange concrete sooner than 12 hours after casting unless the release strength has been reached. Transport precast girders at least 7 days after final concrete placement and upon reaching the requir ed 28 -day compressive strength. Do not place any loads on precast units until the 28 -day compressive design strength is reached. Store precast members in the precast yard and at the jobsite on level, stable foundations that will keep them in a vertical p osition and prevent twisting or rotation. Support girders on only two points of support within a distance not greater than 3% of the beam length from their ends. When approved, cantilever beams may be supported at locations other than near the ends. Provid e a clean and well drained storage area. Prevent excessive or differential settlement of members by storing them on stable ground and on dunnage of sufficient size, shape , and strength to prevent crushing. Immediately pick up members that have rotated or twisted and adjust supports to provide level and uniform support for the members. Support concrete box beams and U -beams beneath end diaphragms during handling, storage, hauling , and erection. When members are stacked, separate them with blocking arranged in vertical planes that will not crush under load. Stack members so that lifting devices are not damaged. Rearrange improperly stored members and inspect them for damage. Members that are improperly stored and become cracked, warped, or otherwise damaged in storage may be rejected. PRESTRESSED CONCRETE AND PRECAST MEMBERS 503 263 Where feasible, base the selection of storage sites, storage conditions and orientation upon consideration of minimizing the thermal and time -dependent creep and shrinkage effects on the camber and/or sweep of the membe rs. Measure and record the sweep and camber of beams monthly. Keep the measurement records on file for review at any time , and upon request, provide a copy of these measurements. If the sweep exceeds the tolerance specified, take immediate measures to bri ng the sweep of the product back to within tolerance. Give notification immediately when the sweep or camber exceeds the specified tolerances. Provide tie -downs, anchors, temporary shoring, diaphragms, and other devices to keep members stable and in-place before they are permanently incorporated into the work. When railroad or roadway traffic must be maintained beneath beams already placed, protect traffic against falling objects during the erection of diaphragms and other structural members, during the p lacing of cast -in-place concrete, and during the erection and dismantling of forms. Protect traffic with nets or flooring with openings not larger than 25 mm ( 1 in.) or as approved. Provide 15 days written notice before starting erection. Submit erection drawings according to Subsection 105.02. Do not consider the approval of erection drawings as relieving the responsibility for the safety and adequacy of methods or equipment or from carrying out the work in full accordance with the plans or specification s. Erection drawings shall include complete details of the erection plan and procedure to include but not limited to:

503.03.12 (a).

503.03.12 (h).

503.03.12 Repair of Precast Members. Repair cosmetic and minor defects in precast members and provide

an engineering evaluation for the repair of major defects as indicated in Subsection 503.13.11 and herein. Submit proposed alternate repair methods for approval. For each project, maintain a record of precast member defects and repair methods. Include in the record information about product description, unit production number, casting date, defect description including dimensions, repair method and materials, defect discovery date, and signature of producer’s Q uality Control Manager indicating concurrence with the information. Do not ship products, which require repairs, from the casting yard to the project site until such repairs are complete and approved . Before beginning the repair of member defects , remove laitan ce, loose material, form oil, curing compound and deleterious matter from repair area. Nonshrink grout shall conform to Subsection 503.02.03. Mix, apply, and cure the grout in accordance with the manufacturer’s recommendations. Apply epoxy bonding agent s according to the manufacturer’s recommendations and as directed. Cure repaired surfaces for 72 hour s or as otherwise indicated in the written recommendations from the manufacturer of the repair products . Ensure the repaired surfaces have a surface textu re, finish , and color that matches the appearance of the unaffected surrounding area of the product.

728.03 01.

Prior to commencing epoxy injection repair, submit specifications on the epoxy materials and injection equipment , Material Safety Data Sheets , and a written procedure for the injection process. Clean the areas surrounding the crack of deteriorated concrete. Remove contaminants that may be detrimental to adhesion. The crack may be ruffed or veed in to accommodate insertion of injection ports. Perform drilling of the crack for injection ports with a vacuum attached swivel drill chuck. The crack may be slotted to facilitate installation of injection tees. Seal the surface of the crack and the area surrounding the entry ports with an approved epoxy. Use approved entry port devices spaced at intervals to insure full penetration of the epoxy. Use a surface seal epoxy of adequate strength to hold injection ports firmly in place and to resist injection pressures to prevent leakage during injection. Accomplish injection of the epoxy by a mach ine capable of metering and mixing the component proportions with a tolerance of 2.0%. Operate the injection machine at a nozzle pressure of approximately 172 kPa (25 psi). Begin injection of epoxy at the lower entry port and continue until appearance of epoxy at the adjacent port. Perform epoxy injection in the next adjacent port where epoxy has appeared. Continue this operation until the cracks are completely filled. Upon completion of the injection of epoxy and after initial cure, remove the entry ports and patch the area. 503 PRESTRESSED CONCRETE AND PRECAST MEMBERS 268 (h) Engineering Evaluation and Repair Proposal . For repair of major defects, submit an engineering evaluation and repair proposal for approval. Allow 14 days for proposal review and final disposition. Do not commence repairs to major defects before receiving written approval of the proposal. Include the following information in the proposal:

503.03.1 3 Surface Finish of Precast Members. Apply an ordinary surface finish to all precast concrete

member surfaces as described in Subsection 502.03.18, unless otherwise noted on the plans. Finish the to p interface between precast concrete members and cast -in-place concrete decks by screeding the concrete to provide a dense surface without a smooth sheen or laitance . Just prior to the concrete reaching its initial set, texture the interface surface. Use a steel brooming tool to etch the surface transversely to the member leaving grooves 6 mm (1/4 in.) to 13 mm (1/2 in.) wide, between 6 mm (1/4 in.) and 13 mm (1/2 in.) deep, and spaced 6 mm (1/4 in.) to 13 mm (1/2 in.) apart. METHOD OF MEASUREMENT

503.04 01 Measurement. Precast concrete members (reinforced or prestressed) will be measured by the each.

The length of the members shown in the estimate of quantities and/or in the proposal are nominal. For exact length see the drawings of the members shown on t he plans. If concrete in precast concrete members fails to meet the specified 28 day compressive strength, liquidated damages will be assessed or the concrete will be rejected, all according to Sections 501 and 502. Liquidated damages will be based on the value of the concrete in a given member being equal to 50% of the contract unit price bid per unit for the members. Prestressing cast -in-place concrete will be measured by the lump sum. The concrete for post -tensioned cast -in-place concrete structures will be measured under Section 502. The reinforcing steel for post -tensioned cast -in-place concrete structures will be measured under Section 505. Additional concrete or reinforcing steel required by the particular system used will not be measured or paid for directly. BASIS OF PAYMENT

503.05.01 Payment. The accepted quantities, measured as provided above, will be paid for at the contract

price per unit of measurement for the pay items listed below that are shown in the proposal. Payment will be full comp ensation for the work prescribed in this Section. Payment will be made under: Pay Item Pay Unit (length) Precast Concrete Members ................................ ................................ ................................ ................................ .................. Each Prestressing Cast -In-Place Concrete ................................ ................................ ................................ ................................ ....... Lump Sum 269 SECTION 504 LIGHTWEIGHT CONCRETE FOR STRUCTURES DESCRIPTION

504.01.01 General. This work consists of furnishing and placing lightweight Portland cement concrete in

bridges, culverts, and other types of concrete structures. MATERIALS

504.02.01 General. Material shall conform to the following Sections and Subsection:

Portland Cement Concrete ................................ ................................ ................................ ................................ ..................... Section 501 Admixtures ................................ ................................ ................................ ................................ .............................. Subsection 501.02.04 Concrete Structures ................................ ................................ ................................ ................................ ............................... Section 502 Aggregates for Portland Cement Products ................................ ................................ ................................ ............................. Section 706

504.02.02 Concrete Making Properties. Lightweight concrete shall be subject to the following requirements

and test methods: Test Test Method Requirements Making Test Specimens (laboratory) ................................ ............... ASTM C192 ................................ .......... — Making Test Specimens (field) ................................ ........................... Nev. T428 ................................ .......... — Compressive Strength ................................ ................................ ..... ASTM C39 * ................................ ....... Table I Unit Weight & Cement Factor (wet) ................................ .................... Nev. T435 ................................ ....... Table I Tests for Popouts ................................ ................................ ............ ASTM C330 ............................ No Surface Popouts Air Content ................................ ................................ ......................... Nev. T431 ................................ ....... Table I Slump ................................ ................................ ................................ . Nev. T438 ................................ ....... Table I Air Dried Weight ................................ ................................ .............. ASTM C567 ................................ ....... Table I Coring Concrete ................................ ................................ ................ ASTM C42 ........................... Subsection 504.04.01 * The compressive strength requirements of Portland cement concrete will be based on the strength test, which is defined as the average of the breaking strength of 3 standard cylinders at 28 days. The compress ive strength test will be required for each 38 m3 (50 yd3), or portion thereof, placed each day. For large continuous pours, one test near the beginning of the pour and one test near the end of the pour may be substituted for the 38 m3 (50 yd3) requirement. Other cylinders may be made and broken for informational purposes. CONSTRUCTION

504.03.01 General. The construction of conventionally reinforced lightweight concrete structures shall conform

to Sections 501 and 502, with the exceptions contained in this Section. Give not less than 32 days notification in advance of use of the proposed sources of materials and make arrangements for the Engineer to obtain samples as required for testing purposes. Samples will not exceed 225 kg (500 lb) fo r each separate grading. Furnish a written statement giving the amount of cement in kg/m3 (lb/yd3), the proportions of cement and each size of aggregate in a saturated surface dry condition, the slump, and the percentage of air in the concrete proposed for use in the work. If proposing to use an admixture other than an air -entraining agent, state its complete brand name and the quantity proposed to be used per m3 (yd3) of concrete. The Engineer, after making such tests as deemed advisable, will either acc ept the proposed materials and proportions or suggest modifications needed for acceptance. After acceptance of batch proportions and materials, do not alter them during the course of the work except as found necessary to maintain yield, amount of cement, and unit mass within specification requirements. Do not revise batch proportions resulting in concrete that contains an amount of total water per cubic meter (cubic yard) greater than 105% of that contained in concrete of the accepted proportions.

504.03 02 Storage of Aggregates. Stockpile lightweight aggregate on the job or at a central batching plant for

a minimum time of 24 hours before its use. Stockpile fine and coarse aggregates separately.