478Cover Depth Survey will be measured in square yards and will be paid for at the contract unit price per square yard. This price shall include furnishing all personnel and equipment required to perform, document, and deliver the survey to the Engineer. Payment will be made under: ————————————————————— Pay Item Pay Unit————————————————————— Concrete (Class) item Cubic yard Bridge-deck grooving Square yard Cover Depth Survey Square yard————————————————————— SECTION 405—PRESTRESSED CONCRETE
405.01 Description
These specifications cover the use of prestressed or post-tensioned hydraulic cement concrete when called for on the plans.
405.02 Materials
a.Concrete shall conform to Section 217, Class A5, with the following exceptions: Each project, and bridge unit within a project (if multiple bridges are part of the same project) shall have an approved mix design that accounts for the closest bar spacing in that girder or other element supplied. The maximum top size of aggregate shall not exceed one-fifth of the narrowest dimension of the concrete formwork, three-quarters of the narrowest clear spacing between reinforcing steel bars or bundles of bars and/or strands, or three-quarters of the minimum clear cover over the steel reinforcement. The concrete mix proportions shall be submitted to the Engineer for review prior to production. No. 57, 7, 68, or 78 aggregate may be used for coarse aggregate subject to the limitations for the top size of coarse aggregate above.
b.Concrete admixtures shall conform to Section 215.
c.Epoxy-resin compounds shall conform to Section 243.
d.Steel reinforcement and prestressed tendons shall conform to Section 223.
e.Structural steel shall conform to Section 226.
f.Bedding materials and bearing pads shall conform to Section 237 and Section 408.
g.Waterproofing shall conform to Section 416.
h.Hydraulic cement mortar and grout shall conform to Section 218.
i.Fully or partially embedded steel attachments to the prestressed concrete members shall be galvanized in accordance with Section 233.404.08 479405.03—Plant Review Plants that manufacture precast, prestressed concrete elements shall have PCI certification for all product groups and categories fabricated for use on Department work at that location. PCI inspection reports shall be on file at the plant and available for review by the Engineer. Plants that have not previously produced products for the Department will be inspected by the Department prior to commencement of production. The Contractor shall provide and furnish a Type III field office in accordance with Section 514 for use in the Engineer’ s inspection of material and workmanship within the shop. In addition to the requirements specified therein, the Contractor shall provide telephone service by a direct access line, a telephone, and maintenance thereof. Costs for installation of the direct access line, the telephone, maintenance, and local service shall be borne by the Contractor. The cost for long-distance will be borne by the Department. The Engineer shall be allowed free access to the necessary parts of the work for inspection purposes. One inspection of corrective action taken on defective material or defective fabrication will be performed by the Department without cost to the Contractor. The cost of further additional inspections shall be borne by the Contractor. The Contractor shall request a plant inspection by the Engineer at least 21 days prior to the start of production. As a part of the plant inspection, a meeting will be held with the producer, Contractor, Engineer, and Inspectors to discuss plant facilities, materials, production methods, review and accep - tance of drawings, and production schedules. In order to qualify new plants for the manufacture of prestressed units other than piles, the Engineer may require the Contractor to test a unit that is representative of each design type and size of unit to be manufactured. The acceptance test shall be as follows: Not more than one line of units shall be cast prior to the satisfactory completion of the acceptance test. A representative unit shall be tested in accordance with VTM-20 in the presence of the Engineer prior to plant approval. The Engineer will randomly select the unit to be tested. The Engineer must approve jigs and load-testing equipment. The Contractor shall be responsible for the cost of testing and the units selected for testing.
405.04 Concrete Controls
The Contractor is required to perform Quality Control during production. Qualified personnel including certified Concrete Technicians and testing equipment shall be supplied by the Contractor. The quality of the concrete shall be monitored by testing fresh concrete properties and testing cylinders in compression. Fresh concrete shall be tested in accordance with Section 217. The Contractor shall prepare two clusters of cylinders for each bed used in production each day concrete is placed. Each cluster shall include a sufficient number of cylinders to demonstrate the product meets the requirements of the Contract, but not less than 12 cylinders per cluster. Failure to have an adequate number of cylinders in each cluster to meet this requirement shall be cause for rejection. Each of the two clusters shall be placed at quarter points of the bed and cured with the product under the same conditions. Prestressed concrete shall meet the compressive strength specified at release, f ‘ci, prior to detensioning, stripping the forms, and handling the product, and the specified 28-day minimum design compressive strength, f ‘c, prior to shipment. In the event that there is no specified compressive strength at release in the Contract, the product shall have a compressive strength of 80 percent of f ‘c. When using 6 x 12 405.04 480cylinders, two cylinders from each cluster shall be tested to determine compressive strength, and three cylinders from each cluster shall be used when using 4 x 8 cylinders. The reported compressive strength shall be the average of the strength measured of the two or three cylinders tested as specified above in accordance with ASTM C39. The test results shall be recorded in a bound log book along with the date of casting and the age of the cylinder at testing and made available to the Department inspector. Detensioning or handling an element prior to obtaining the release compressive strength will be cause for rejection. Concrete batches from which cylinders are made shall be tested for slump in accordance with ASTM C143, and for air content in accordance with ASTM C231. The Contractor shall maintain records of tensioning operations, curing temperatures, and concrete testing in a form suitable for permanent filing. Records shall be available to the Department and maintained for 10 years.
405.05 Procedures
a.Forms: Forms and centering shall be made and maintained true to the shapes and dimensions shown on the approved drawings. Forms shall be of metal or other material that will give comparable results. Forms shall be designed and aligned so that they will not restrict the longitudinal movement of the casting when the pre - stressing force is transferred. Drilled holes in bulkheads and templates shall be sized to provide for unrestricted movement of strands during tensioning. Bulkheads may be constructed of adequately reinforced plywood. Wooden bulkheads that are warped or damaged shall not be used. Form ties shall not be used without the approval of the Engineer. Joints between panel forms shall be well aligned and tight; and adequate precautions shall be taken to prevent leakage of mortar. Corners or intersections of surfaces exposed in the completed structure shall be chamfered or rounded, with a width or radius of 3/4 inch. Corners of square piles shall be chamfered from 3/4 inch to 1 1/2 inches or rounded to a 2-inch radius. A smaller chamfer not less than 3/4 inch may be used if approved by the Engineer. V oid forms shall be anchored during concrete placement and secured by means other than being tied to strands. The material used to form internal voids for voided slab and box sections shall be expanded poly - styrene having a maximum water absorption (by volume) rate of 10%. The use of waxed-coated cardboard tubes shall not be permitted. Precast prestressed concrete box beams and flat slabs shall have one drain provided in each end of each void. The drain shall be located so that the void will drain after the unit has been installed in the structure. The device for forming the drain shall be of such material and design that the drain will not rust, stain, or otherwise disfigure the concrete and shall allow free drainage from the void.405.04 481(b) Placing Strands and Wires and Applying and Transferring Pretension: The Contractor may be required to submit for the Engineer’ s approval the detailed computations of gage pressures and elongations proposed. All steel reinforcement shall conform to Section 406. Wires shall conform to the requirements herein for strands. The Contractor shall not substitute stress-relieved strands for low-relaxation strands. Strands with kinks, bends, nicks, broken wires, scales, rust, or other defects shall not be used. The failure of one wire in a seven-wire pretensioned strand or one wire in a parallel-wire post-tensioned cable may be accepted provided the wire is not more than 2 percent of the total number of wires. Slight rusting will not be cause for rejection provided it is not sufficient to cause visible pits. Strands shall be satisfactorily cleaned before concrete operations begin. Strands shall be placed in proper position and first tensioned individually by a force of at least 5 but not more than 25 percent of the final stressing force. This force shall not vary by more than 5 percent in any group of strands. The final stressing of strands shall be performed by applying tension to each strand individually or to all strands as a group. The strand or strand group shall be tensioned to the total pretensioning force as indicated on the plans, with a maximum applied stress of 70 percent of the ultimate strength for stress-relieved strands and 75 percent of the ultimate strength for low-relaxation strands. During stressing, allowance shall be made for the amount of strand anchorage slipping. The proper allowance shall be determined during trial plant operations and satisfactorily checked periodically during actual stressing operations. Strand anchorage devices of each type and source shall be checked as specified herein. During stressing, allowance shall be made in the amount of strand elongation for the loss or gain in tension resulting from the change in temperature in the strand between the time of stressing and time of the initial set of concrete. The magnitude and method of application of this allowance shall be in accordance with the PCI Manual for Quality Control (MNL-116). A manufacturer’ s corresponding recommended value for the average modulus of elasticity will be used for each order of strand supplied. Consideration shall be given to the stress-strain data of tests performed on the samples. Strands shall not be spliced within units. Pretensioned strands shall be secured by suitable anchorage devices capable of developing at least 90 percent of the ultimate strength of the strand. When deflected strands are tensioned in their deflected position, they shall be supported by lubricated rollers with solid bushings or other low-friction rollers at hold-up and hold-down points. Provisions shall be made for a cover of at least 1/8 inch of concrete or epoxy mortar on metal parts of the hold-down devices remaining in beams. The final position of strands and reinforcing steel shall be accurately maintained as shown on the plans.405.05 482The tensioning system shall be equipped with a pressure gage indicating the jack pressure to an accuracy of within 2 percent of the pressure corresponding to the full prestress tension in the strand. Gages shall be recalibrated at least once every 6 months, at any time the gaging system appears to be giving erratic or erroneous results, or if the gage indication and elongation measurements indicate materially different stresses. Gages, jacks, and pumps shall be calibrated as a system in the same manner in which they are used in tensioning operations. Calibration shall be performed by an approved testing laboratory or approved calibration service, and a certified calibration curve shall accompany each tensioning system. Load, as measured by gage pressure, shall not vary from that measured by elongation by more than 5 percent. Elongation measurements shall be taken as checks on the final pressure gage reading. Elongation shall be measured to a precision of 1/4 inch. The Contractor shall record elongation and pressure readings during stressing. Calibration documentation shall be provide to the Department representative upon request. Tension in the strands shall not be transferred to the concrete in the unit until the concrete has attained a compressive strength of f’ ci, in accordance with Section 405.04. Strands shall be transferred gradually, simultaneously, and equally to the concrete when multiple-strand detensioning is used. When the single-strand release method is used, strands shall be released by heating near the end of each unit in accordance with the Contractor’ s sequence and schedule. Individual jack release or burning may be used for strands at the dead or live end of the bed. Strands to be released in each step of the sequence shall be burned apart between beams before the next step is begun. No more than two strands shall be included in each step of the pattern. Strands shall not be burned quickly but shall be heated with a low-oxygen flame played along the strand at least 5 inches until the metal gradually loses its strength and failure of the first wire in each strand occurs after the torch has been applied for at least 5 seconds. The schedule for single-strand detensioning of units having deflected strands shall incorporate the following:
1.Straight strands located in the upper flange of the unit shall be released first.
2.Tension in the deflected strands at the ends of bed and uplift points shall be released in sequence.
3.Hold-down devices for deflected strands shall be disengaged, and hold-down bolts shall be removed from units.
4.The remaining straight strands of the pattern to be detensioned individually shall be released in sequence. If it is desired to release hold-down devices prior to releasing tension in deflected strands, this may be permitted if the weight of the prestressed unit is more than twice the total of the forces required to hold strands in the low position, or if weights or other approved vertical restraints are applied directly over the hold-down points to counteract uplifting forces at least until the release of deflected strands has proceeded to such a point that the residual uplifting forces are less than 1/2 the weight of the unit. Failure to follow these procedures may result in rejection of the units.
c.Placing Concrete: The procedure and equipment for handling, placing, and consolidating concrete shall be such that a uniformly dense and high-grade of concrete is obtained in all parts of the unit under all working and weather conditions.405.05 483When placing concrete in continuous horizontal layers in forms for precast I-beams, succeeding layers shall follow the preceding layer before any initial set takes place. Concrete in bottom slabs of precast prestressed box beams shall be placed before void forms are positioned. Concrete may be placed in forms for piling and precast slab units in one continuous horizontal layer. The use of external vibration shall be at the option of the Contractor; however, improper placing and vibrating may be cause for rejection. Concrete shall not be placed in forms when the temperature of the forms or embedded items is below 40 degrees F .
d.Removing Forms: Forms for units being moist cured may be removed when concrete reaches the specified compressive strength at release of f’ ci. After forms are removed, the Engineer will inspect units to determine their acceptability. Patching of any surface irregularities, especially those resulting from honeycombing, shall be performed only after inspection and authorization. After form removal, the Contractor shall mark each precast unit with a unique identifying number specific to the project.
e.Finishing: Holes and voids in the surface of concrete resulting from bolts, ties, or large air pockets shall be wetted and filled with mortar having the same proportion of fine aggregate and cement as in the concrete, after which exposed mortar surfaces shall be finished smooth and even with a wood float. If finishing work is necessary, the exterior face of exterior beams shall be finished free from blem - ishes and then rubbed with burlap. Holes or voids having a depth or diameter greater than 1/2 inch on the interior face of exterior beams, on both faces of interior beams, or on piles shall be filled and finished. Surfaces to be repaired and finished shall be kept wet for at least 1 hour before hydraulic cement mortar is applied. Immediately following patching work, repaired areas shall be wet cured for at least 48 hours. The wet cure may be accomplished by the use of steam, wet burlap, or continuous spray wetting, or liquid membrane-forming compound may be used on noncomposite surfaces. Epoxy may be used and shall be applied and cured in accordance with the manufacturer’ s recommendations. Piles subject to tidal waters shall be finished in accordance with Section 404.03(i). Units that are to be made composite with subsequently placed concrete shall be finished by striking off the top of forms. As soon as the condition of the concrete permits and before it has fully hard - ened, dirt, laitance, and loose aggregate shall be removed from the surface by means of a wire brush, which shall leave the coarse aggregate slightly exposed or otherwise roughened to an amplitude of 1/4 inch. If concrete has been allowed to harden so that it is impossible to remove laitance and roughen the top surface of units by brushing, the surface shall be cleaned and prepared for bonding by chipping. Ends of strands shall be allowed to cool to normal temperature after cutting and then shall be cov - ered with at least 1/8 inch of epoxy mortar or other material approved by the Engineer. After mortar is allowed to cure, the entire end of the unit shall be covered with epoxy, Type EP-3T. Care shall be taken in cutting or burning ends of strands to prevent damaging the concrete surface.405.05 484(f) Protecting and Curing: Prestressed concrete shall be cured by being kept moist at temperatures that will promote hydration. Proper curing by any method requires that moisture is retained for complete hydration and the formation of surface cracks attributable to rapid loss of water is prevented while the concrete is plastic. Prior to concrete placement, procedures for retaining moisture shall be approved by the Engineer. Moist curing shall continue until such time as the compressive strength of the concrete reaches the strength for detensioning. Moist curing shall commence as soon as possible following the completion of surface finishing. The Contractor shall have the option of using steam curing in lieu of moist curing in accordance with the following:
1.The design concrete mixture shall be proven adaptable for steam curing using the same cure as proposed for the routine manufacture of prestressed concrete units.
2.The Contractor shall be responsible for the quality of concrete placed in any weather or atmospheric condition. At the time of placement, concrete shall have a temperature of 40 degrees F to 90 degrees F when concrete is moist cured. If accelerated steam curing is used, the temperature of the concrete at placement shall be 40 degrees F to 100 degrees F . Mixing limitations shall be in accordance with Section 217.09.
3.An initial set of a nominal 500 pounds per square inch, determined by the penetration resistance test, shall be obtained prior to the introduction of steam. The penetration resistance test shall be performed in accordance with ASTM C403. Forms shall be covered after surface finishing of the concrete, including the delay period before introduction of steam.
4.The temperature rise in the curing enclosure shall be uniform, with a rate rise of not more than 80 degrees F per hour. Concrete shall be cured at a steam temperature of not more than 180 degrees F , with the steam temperature uniform throughout the curing enclosure and with a variation of not more than 20 degrees F . Approved recording thermometers shall be placed so that temperatures can be recorded at a minimum of two uniformly spaced locations in each curing enclosure.
5.Steam curing shall be maintained until such time as the compressive strength of the concrete attains that specified on the plans for detensioning.
6.Steam curing shall be performed under a suitable enclosure to retain the live steam at 95 percent relative humidity and minimize heat losses. Enclosures shall allow free circulation of steam. Steam jets shall be positioned so that they will not discharge directly on concrete, forms, or test cylinders.
7.Concrete test cylinders shall be subject to the same curing conditions as the units.
8.Immediately after steam curing is terminated, forms shall be loosened and the stress load on the stressing strands shall be released while the concrete is still hot.
g.Waterproofing: Units so designated on the plans shall be waterproofed in accordance with Section 416.
h.Handling, Storing, and Erecting: Units shall be adequately separated in storage immediately following removal from beds to make inspection of finished surfaces possible and to facilitate repair of surface blemishes.405.05 485Care shall be taken in handling and storing units to avoid damage to concrete. Concrete must have attained the minimum 28-day design compressive strength before structural units are shipped to the project site. Piles shall not be driven until at least 7 days after the date concrete is cast and has attained the minimum design compressive strength. Lifting and support points for all units shall be as shown on the Plans. If the Plans do not indicate lift - ing and support points, the Contractor shall lift and support units at locations not less than 6 inches or more than the depth of the unit from the end of the unit. The Contractor shall be responsible for the design and safety of the lifting device used. Piles shall be supported at lift points as shown on the Plans. Requests by the Contractor to use lifting or support points other than those indicated must be accompanied by computations showing that stresses are within the allowable range using 50 percent of the dead load as an impact factor. Units that have been damaged in handling shall be repaired to the satisfaction of the Engineer. Units that have been damaged to such an extent that they are not repairable shall be replaced at no expense to the Department. Recesses at ends of transverse ties, holes for anchor bars, and other recesses shown on the plans shall be filled with mortar conforming to Section 218. Mortar shall be applied in one continuous operation for each span. Where waterproofing material is to be applied to tops of units in the field, longitudinal joints shall be sufficiently smoothed to prevent damage to the material. Shear keys required between adjacent units shall be constructed using the material shown on the Plans. Struts and diaphragms between spread units may be cast separately or monolithically with the deck slab. If the Contractor casts struts and diaphragms separately from the slab, deck slab concrete shall not be placed until concrete in the struts or diaphragms has attained 80 percent concrete strength (f’c). If the Contractor casts struts and diaphragms monolithically with the slab, each prestressed concrete beam shall be placed and restrained in such a manner that the beam will not be canted during construction of the struts, diaphragms, and slab. The Contractor’ s method for maintaining acceptable vertical alignment of beams shall be subject to the approval of the Engineer. Bearing surfaces of units shall be parallel to the bottom surface of the unit or as specified on the plans. Attached bearing assemblies shall be fabricated so that their bottom bearing surfaces shall lie in truly horizontal planes in their erected position. Metal bearing plates or bottoms of precast beams that are to bear on elastomeric pads shall be coated with epoxy, Type EP-2, EP-4, or EP-5, and then surfaced with a No. 36 to No. 46 silicon carbide or aluminum oxide grit. Ends of beams, at ends of spans, and diaphragms shall be vertical. Continuity diaphragms for prestressed beams shall not be cast until at least 90 days after the strands in the beams have been detensioned. Units shall be stored on dunnage placed at the support points shown on the Plans and at least 4 inches above the ground. If supports points are not provided on the Plans, the Contractor may locate the dunnage at the lifting points or bearings. If units are stacked, they shall be so arranged that the weight of upper members does not introduce shear or bending effects onto members below. The Contractor shall make all units accessible for inspection by the Engineer upon request.405.05 486Once beams, girders, or slabs have been placed on temporary supports for storage, camber measure - ments shall be taken at midspan, at release and at 2 week intervals thereafter up to 120 days after detensioning. These measurements shall be recorded in the morning to reduce the effects of solar radiation for each unit and shall include the date, time, weather conditions, and measurements taken. Piles or other elements supported at more than two points shall have their camber measured at the midpoint of each supported span. Camber shall be measured and recorded in a bound log book and made available to the Inspector. Camber measurements that fall outside the tolerances below shall be reported in writing to the Engineer and will be cause for rejection if not corrected to the satisfaction of the Engineer. Each measurement shall include the date of casting, the date of the measurement, the time of day, the temperature and other weather conditions (as directed by the Engineer) along with the measurement. The Contractor shall submit a camber management plan to the Engineer prior to fabrication indi - cating the method for controlling camber. Units shall not be loaded before the 28-day compressive strength is achieved and no earlier than 7 days. The Engineer will review the plan, and once found to be acceptable, the Contractor shall implement the plan if any of the thresholds below are exceeded: • 75 percent of the design camber at erection on the Plans • 75 percent of the allowable limit between adjacent beams, girders or slabs • 3/4 inch difference between the high and low units in the same span (for slabs or box beams) The Contractor shall implement the camber management plan for any beams, girders or slabs that will be erected 120 days or more after detensioning. Where a change in construction schedule occurs which will result in erection 120 days or more after detensioning, the Contractor shall implement the camber management plan. When a camber management plan is implemented, camber measurements shall be taken after loading the units. Subsequent camber measurements can be taken in the loaded state. Camber shall be measured within 3 days prior to shipping in an unloaded state. The Contractor may submit a request to delay the implementation of the camber management plan to the next scheduled camber measurement if documentation is submitted showing the camber growth is following an established camber development path that will not exceed the camber tolerance at erection under the current construction schedule. If accepted by the Engineer, the Contractor shall implement the camber management plan at the next scheduled camber measure - ment unless a subsequent request is made and approved by the Engineer. No beam, girder or slab exceeding the camber tolerance at erection shall be shipped to the jobsite unless approved by the Engineer. All field welding, such as field welding of sole plates or other metallic components, shall be performed in accordance with Section 407. Coatings shall be repaired in accordance with Sections 233 and 411 as applicable. Payment for field welding, inspection, and coating shall be included in the price bid for other items.405.05 487405.06—Tolerances The limits of tolerance do not necessarily represent fully acceptable construction; they are the limits at which construction may become unacceptable. In general, workmanship shall be at a level of quality that will be well within the tolerance limits.
a.Precast Prestressed Concrete I-Beams and T-Beams: Characteristic Values Depth (overall) ±1/4 inch Width (flanges and fillets) ±1/4 inch Width (web) ±1/4 inch Length of beam ±1/8 inch/10 ft or 1/2 inch, whichever is greater Exposed beam ends (deviation from square Horizontal ±1/4 inch, vetical or designated skew) ±1/8 inch/ft of beam height Side inserts (spacing between centers of inserts ±1/2 inch and from centers of inserts to ends of beams) Bearing plate (spacing from centers of bearing ±1/2 inch plates to ends of beams) Stirrup bars (projection above top of beam) ±3/4 inch Stirrup bars (longitudinal spacing) ±1 inch Horizontal alignment (deviation from straight Max. 1/8 inch/10 ft line parallel to centerline of beam) Camber differential between adjacent beams 1/8 inch/10 ft or max. 1/2 inch of same type and strand pattern (at time of erection) Camber differential from design camber +30% to -50% at erection on plans (at time of erection) Center of gravity of strand group ±1/4 inch Center of gravity of depressed strand group ±1/4 inch at end of beam Position of hold-down points for depressed strands ±6 inches Position of handling devices ±6 inches
b.Precast Prestressed Concrete Box Beams and Flat Slabs: Characteristic Values Depth (top slab) +1/2 to –1/4 inch Depth (bottom slab) 0 to +1/2 inch Depth (overall) ±1/4 inch Width of web or thickness of sidewalls ±3/8 inch Width (overall) +1/8 to –1/4 inch Length ±1/8 inch/10 ft or 1/2 inch, whichever is greater V oid position (longitudinal) from Plan locations ±1/2 inch ±1 inch adjacent to end block Square ends (deviation from square) ±1/4 inch Skew ends (deviation from designated skew) Skew angle equal to or less than 30° ±1/4 inch Skew angle greater than 30° ±1/2 inch405.06 488Horizontal alignment (deviation from straight Max. 1/8 inch/10 ft line parallel to centerline of unit) Gap between adjacent units Max. 1/2 inch Tie rod tubes (spacing between centers of tubes ±1/4 inch and from centers of tubes to ends of units) Tie rod tubes (spacing from centers of tubes ±1/4 inch to bottom of beam) Longitudinal begin/end position of Virginia ±3 inches Adjacent Member Connection blockouts Camber differential between adjacent units Max. 1/4 inch (at time of erection) Camber differential between adjacent units with Max. 1/2 inch (at time of erection) Virginia Adjacent Member Connections Camber differential between high and low Max. 3/4 inch (at time of erection) units in same span Camber differential from design camber at +30% to -50% erection on plans (at time of erection) Side inserts (spacing between centers of inserts ±1/2 inch and from centers of inserts to ends of beams) Stirrup bars (projection above top of beam) ±3/4 inch Stirrup bars (longitudinal spacing) ±1 inch Center of gravity of strand group ±1/4 inch Center of gravity of depressed strand group ±1/4 inch at end of beam Position of hold-down points for depressed strands ±6 inches Position of handling devices ±6 inches
c.Prestressed Concrete Piling: Characteristic Values Width or diameter –1/4 to +3/8 inch Head out of square 1/16 inch/12 inch of width Length of pile ±1 1/2 inch Horizontal alignment (deviation from Max. 3/16 inch/20 ft of length straight line parallel to centerline of pile) Max. 1/8 inch in 10-ft chord Max. 1/16 inch in 1 ft V oid location ±1/4 inch Stirrup bars or spiral position ±1 inch Center of gravity of strand group ±1/4 inch Position of handling devices ±6 inch
405.07 Measurement and Payment
Prestressed concrete piles will be paid for in accordance with Section 403.08. Prestressed concrete structural units that are to be incorporated in the completed structure will be measured in units of each for the unit specified and will be paid for at the contract unit price per each. These prices shall include manufacturing, fabricating, and furnishing units, mortar seals on ends of units; structural and reinforcing steel for connecting units to struts and diaphragms; reinforcing, structural, 405.06 489and prestressing steel embedded in units, including dowels in place and bearing pads or bearing devic - es; post-tensioning fittings, strands, and rods, grouting, joint fillers and sealers, waterproofing applied to structural units at the prestressing plant; testing and documentation, hauling, handling, storage, and treatment. Payment will be made under: ————————————————————————————Pay Item Pay Unit————————————————————————————Prestressed concrete (Shape, beam, Each description of cross section, and length) Prestressed concrete slab (Width, depth, and length) Each———————————————————————————— SECTION 406—REINFORCING STEEL
406.01 Description
This work shall consist of furnishing; coating, if required, and placing reinforcing steel or wire mesh used in concrete operations, except prestressed strands and wires, in accordance with these specifications and in conformity to the lines and details shown on the plans.
406.02 Materials
a.Steel used for reinforcement shall conform to Section 223. Except for spiral bars, bars more than 1/4 inch in diameter shall be deformed bars.
b.Welded wire fabric shall conform to Section 223.
c.Bar mat reinforcement shall conform to Section 223.
d.Corrosion resistant steel used for reinforcement shall conform to Section 223.
406.03 Procedures
a.Order Lists and Bending Diagrams: Copies of order lists and bending diagrams shall be furnished to the Engineer when required or requested.
b.Protecting Material: Reinforcing steel shall be stored on platforms, skids, or other supports that will keep the steel above ground, well drained, and protected against deformation. When placed in the work, steel reinforcement shall be free from dirt, paint, oil, or other foreign substances. Steel reinforcement with rust or mill scale will be permitted provided samples wire brushed by hand conform to the requirements for weight and height of deformation.
c.Fabrication: Bent bar reinforcement shall be cold bent to the shape shown on the plans. Fab- rication shall be in accordance with the ACI Detailing Manual – 2004 (SP-66-04).406.03
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 506–516 of 1,065.