450PRECAST PRESTRESSED CONCRETE CONSTRUCTION

450-1Description

Fabricate, store, transport and erect precast/prestressed concrete members prestressed by the pretensioning method. Pretensioned precast prestressed concrete products are products prestressed by the pretensioning method. In this method, steel or fiber rein forced polymer (FRP) components are stressed and anchored; the concrete for the product is then cast and cured, and finally the stress in the steel or FRP components is released from the anchorages to the concrete through bond, after the concrete has attai ned its specified release strength. A precast prestressed concrete plant, hereinafter called plant, is an independent operating facility capable of performing all the operations necessary to fabricate precast/prestressed concrete products. Obtain precast /prestressed products from a plant that is currently on the Department’s Production Facility Listing. Producers seeking inclusion on the list shall meet the requirements of Section 105. When the Producer’s Quality Control Program is suspended, accept resp onsibility of either obtaining precast/prestressed products from a precast/prestressed concrete plant with an accepted Quality Control Program, or await re -approval of the Producer Quality Control Program. The Engineer will not allow changes in Contract Ti me or completion dates as a result of the concrete plant’s Quality Control Program suspension. Accept responsibility for all delay costs or other costs associated with the plant’s Quality Control Program suspension.

450-2Quality Control Program

450-2.1General: Develop a Producer Quality Control Program as specified in

Meet the requirements of the accepted Quality Control Program, Contract Documents, and Precast/Prestressed Concrete Institute (PCI) Manual for Quality Control for Plants and Production of Structural Precast Concrete Products (MNL -116). The requirements of the Contract Documents will govern, when there is a discrepancy between the PCI Manual and the Contract Documents. Accept responsibility for performing daily Quality Contr ol (QC) inspections of all phases of work ensuring all materials and workmanship incorporated into the product meet the requirements of the Contract Documents. Also, maintain a daily activity report detailing the results of the daily Quality Control Progra m activities. Ensure these daily reports and minutes of the weekly meetings with the Engineer and the plant’s production personnel are maintained at the plant. During the weekly meetings, discuss the results of the QC inspections. Ensure a QC inspector i s present during concrete placements and performs inspection during all fabrication of precast prestressed concrete products, including the inspection of the operations before, during and after the placement of concrete.

450-2.2Plant: Ensure each plant h as an onsite QC Manager or designee meeting the

requirements of Section 105 at all times during fabrication.

450-2.3Tolerances:

Inspect all prestressed concrete products within five working days of detensioning to ensure their dimensions (other than sweep and camber) conform to the specified tolerances and to determine if there are any deficiencies. 491 FY 2023-24 Return to Table of Contents Inspect the product for conformance with the product dimension tolerances shown in Appendix B of PCI Manual MNL -116, except as modified herein. Apply the tolerances with respect to the theoretical positions and dimensions shown in the Plans. Apply the same tolerances for U -Beams as those specified for I -Beams, when inspecting the product for conformance with dimension tolerances. For Florida U -Beam diaphragms, the tolerances are:

diaphragms.

relative to design plan positions.

diaphragms. The tolerance for beam strand sheathing is plus or minus 2 inches. Ensure the tolerance on all miscellaneous shaping including, but not limited to, chamfers, miters, bevels, keys, tapers, radii, holes , inserts, and block outs is within plus or minus 1/8 inch of the control dimension of the shape. The tolerances represent the total allowable tolerance that will be accepted in the finished product. Do not apply tolerances shown for the overall dimensio ns of a member to violate the tolerances shown for positions of reinforcing and prestressing steel or FRP. Apply the tolerances during and after the fabrication of prestressed products. Do not reduce the concrete cover for reinforcing steel, FRP reinforcin g, prestressing steel, FRP prestressing strands, or any other metallic or polymeric objects specified in the Plans more than 1/4 inch. Do not reduce the concrete cover for reinforcing steel, FRP reinforcing, prestressing steel, FRP prestressing strands, or any other metallic or polymeric objects when the cover specified in the Plans is minimum cover. Limit sweep to 1/2 inch for U -Beams and Inverted T -Beams. The maximum allowable sweep for I -Beams and piles is 1/8 inch for every 10 feet, and will be det ermined by the following equation: Sweep (in) = (0.0125 in/ft) x Length (ft) of beam or pile Measure and record the sweep and camber of the beams immediately after detensioning and monthly. Beyond 120 days after casting, monthly sweep and camber measurements may be reduced to quarterly if there are no identified issues with the beam, and if the sweep and camber measurements are in tolerance. Once the reduced frequency is applied, camber and sweep shall be measured no more than 7 calendar days prior to shipping. Keep the measurement records on file for review upon request by the Engineer. Notify the Engineer immediately when the sweep or camber exceeds the specified tolerances. If the actual camber is less than 50% of the predicted camber at release provided by the Plans, move the dunnage towards the center of the beam to a maximum of 5% of the total length at each end to induce camber. If the camber is outside of the design camber shown in the Plans by plus or minus 1 inch, take appropriate actions to accommodate the product in the structure. If the sweep exceeds the tolerance specified, immediately propose measures to the Engineer to bring the sweep of the product back to within tolerance. Special storage conditions for the purpose of removing ex cessive sweep will not be restricted by requirements of this Section. 492 FY 2023-24 Return to Table of Contents

450-2.4Product Certification: Ensure the QC inspector inspects all completed products

at the plant not less than 24 hours before shipment to verify that all Contract Documents requirements are met. Upon verification that all Contract Document requirements have been met and all necessary repairs have been satisfactorily completed, the product will be stamped with the approved QC Manager stamp identified in the Producer QC Plan. With each monthly request submitted for payment, attach a certification stating that the listed precast prestressed products have been produced under the Producer QC Plan and meet the Contract Document requirements. Ensure the certification is signed by a lega lly responsible person of the plant and is submitted on the plant’s letterhead.

450-2.5Documentation: Ensure that a system of records is maintained in each plant

which will provide all information regarding the certification and testing of prestressings teel, FRP prestressing strands, reinforcing steel, FRP reinforcing, concrete materials and concrete, curing materials, embedded items, tensioning, concrete proportioning, pre -placement, placement, post-placement inspections, curing, and disposition of prod ucts. Include in the record keeping all the deficiencies found as a result of the inspection and testing. Keep certified test reports for all materials incorporated into the production of precast prestressed concrete products. Ensure that the record of t ensioning operations is maintained and reflects the identification of the bed, type of fabricated products, the complete Financial Project Identification Number, jack identification number, date prestressing strands were stressed, temperature at the time o f stressing, and signature of the qualified tensioning machine operator. Ensure the proposed method and format for documenting required information is included in the Producer QC Plan. Maintain records until all the precast prestressed products for a p roject have been fabricated then submit required records to the Engineer. Ensure records are available at all times for the Engineer’s inspection.

450-2.6Quality Assurance Inspection and Testing: The Engineer will perform

periodic inspections, sampling, and testing to ensure of the quality and acceptability of the materials, methods, techniques, procedures and processes being utilized in the fabrication of precast prestressed concrete products.

450-3Materials

450-3.1General: Meet the following requirements:

Concrete ................................ .............................. Section 346 Steel Strands* ................................ ...................... Section 933 Carbon Fiber Reinforcing Polymer (CFRP) Strands*................................ .............................. Section 933 Steel Prestressing Bars ................................ ........Section 933 Steel Accessories ................................ ................ Section 933 Steel Spirals ................................ ........................ Section 931 Reinforcing Steel an d Metal Welded Wire Reinforcement ................................ ..... Sections 415 and 931 FRP Reinforcing ................................ . Sections 415 and 93 2 FRP Spirals** ................................ ..................... Section 932 Embedded Ducts ................................ ................. Section 960 Membrane Curing compounds*** ...................... Section 925 Epoxy Resin Compounds ................................ ....Section 926 Burlap ................................ ................................ ..Section 925 493 FY 2023-24 Return to Table of Contents Curing Blanket ................................ ........................... 400-16 Penetrant sealer*** ................................ .............Section 413 Methacrylate ................................ ....................... Section 413 Epoxy Injection of Cracks ................................ ..Section 411 * Do not use strands from more than one source in any individual prestressed element, with the exception of the partially tensioned strands (dormant strands ). ** The FRP spirals cannot be used in combination with steel prestressing strand . *** Use membrane curing compounds and sealers that are compatible with coating or other materials that are applied to concrete surface. Use inserts in accordance with the recommendations of the manufacturers and within their certified capacities and application qualifications. Do not use aluminum inserts. Use draped strand devices of sufficient rigidity having adequate support to retain the position of the strand unchanged under the induced load. Do not allow the devices to induce friction to the tendons such that the required jacking force and elongation cannot be attained.

450-3.2Strand Chucks and Splice Chucks: For pretensioning, use str and chucks that

are capable of anchoring the strands without slippage after seating and ensure against strand failure within the grips at loads less than 95% of ultimate tensile strength of the prestressing strand. Submit manufacturer’s certification tha t splice chucks used to transmit the

prestressing force from one prestressing tendon to another are capable to hold at least 95% of the

ultimate tensile strength of the prestressing strand.

Do not use wedges that become worn, cracked, deformed, or that allow dead end

seating in excess of 3/8 inch. Use components from the same manufacturer to make up chucks

and to provide proper wedge fit.

Use chucks as complete units. Clean, inspect, and lubricate the chucks between

each use. Use wedges and housing that are compatible and made for the specific type and size of

prestressing strand used. Ensure proper fit and proper seating of wedges on the strands.

The Engineer will allow one splice per strand subject to the following:

piling where up to two splices are permitted to be used in each pile, so long as they are not

located in the same vertical cross section, perpendicular to longitudinal axis of the pile).

direction.

450-4Material Acceptance and Testing

450-4.1Concrete: Perform the QC sampling and testing of concrete in accordance with

the requirements of Section 346.

450-4.2Reinforcing, Welded Wire Reinforcement and Prestressing Strand for

Pretensioning:

450-4.2.1 General: Identify all reinforcing steel, welded wire reinforcement and

prestressing strand for pretensioning by LOTs. A LOT of reinforcing steel or welded wire is a

shipment of material from the same manufacturer and heat. A LOT of prestressing steel is a

shipment of material of the same size, production grade and heat from the same manufacturer. A

LOT of FRP reinforcing bars or prestressing strands is a shipment of material of the same size,

fiber lot and resin batch from the same manufacturer.

Acceptance of reinforcing bars, welded wire reinforcement and

prestressing steel for pretensioning is based on manufacturer’s certification and the Department’s 494FY 2023-24Return to Table of Contents

verification tests. The sampling for verification testing will be performed by the Department at

each plant, on at least two LOTs per year. Additional samples may be taken at the manufacturing

source of reinforcing bars, welded wire reinforcement and prestressing strands.

When products contain the material that has failed to meet the

requirements of 450-3, reject the unused material of the failed LOT. The Engineer may require

an engineering analysis of the products which contain the failed material, in accordance with

Section 6.

450-4.2.2 Steel Reinforcing and Welded Wire Reinforcement: Obtain and

maintain for each LOT a certified mill analysis, physical property test report and the

manufacturer’s assigned LOT number with the heat of the material represented. Verify that the

report represents the steel received and that the steel meets the Contract Documents

requirements. Reject all unidentified reinforcing steel or welded wire reinforcement received at

the plant or job site.

Submit the manufacturer’s certified mill analysis and provide three, 7 foot

long, randomly selected samples from the designated LOT of reinforcing steel and three

randomly selected samples from the designated LOT of welded wire reinforcement when

requested by Engineer. Ensure each sample of welded wire reinforcement covers an area of four

intersections of transverse and longitudinal bars. Ensure the transverse wires of each piece of

welded wire reinforcement extend approximately 6 inches to both sides.

450-4.2.3 Fiber Reinforced Polymer (FRP) Reinforcing: Meet the requirements

of 932-3.

450-4.2.4 Steel Prestressing Strand for Pretensioning: Obtain and maintain for

each LOT of material received, the manufacturer’s assigned LOT number, certified test values

for specified material properties together with a representative load-elongation curve and the

modulus of elasticity value based upon strand nominal area. Submit and support by records

maintained by the strand manufacturer, production tolerances applied in selection of the reported

strand modulus. Verify that documents submitted represent the shipment received and meets the

Contract Documents requirements.

Reject all unidentified prestressing steel received at the plant or job site.

Submit the manufacturer’s certified mill analysis and provide three, 5 foot

long randomly selected samples from the designated LOT of material when requested by the

Engineer.

450-4.2.5 Fiber Reinforced Polymer (FRP) Prestressing Strand for

Pretensioning: Meet the requirements of 933-5.2.2.

450-4.2.6 Strand Chucks and Splice Chucks: Obtain and maintain certified test

results certifying that the material meets the requirements of 450-3.

450-4.2.7 Steel Accessories: Use only steel accessories meeting the requirements

of 450-3.

450-4.2.8 Ducts: Obtain and maintain certified test results certifying that the

material meets the requirements of 450-3.

450-5Shop Drawings

Submit shop drawings for all pretensioned prestressed concrete products containing FRP

bars, FRP strands, or stainless steel strands. Submit shop drawings for all other pretensioned

prestressed concrete products when the Contract Documents do not contain all the detailed

information necessary to fabricate and erect the pretensioned prestressed concrete product.

Ensure the submitted shop drawings meet the requirements of the Contract Documents. 495FY 2023-24Return to Table of Contents

Obtain prior approval of any adjustments to the shop drawings which will result in a net

change of prestressing force within the product. Shop drawings are not required to depict

negligible, supplemental reinforcement used to facilitate fabrication of products if the additions

do not affect the performance of the product.

In lieu of shop drawings, submit the following to the Engineer:

product.

protection systems used on beams.

requirements of the Contract Documents, submit full plan details and Specifications for the

alternate materials and methods. Ensure the alternate materials and methods meet the following

requirements:

interims as referenced in Plans.

Engineer.

after all losses, is not less than or 5% greater than that provided by the stranding shown in the

Plans.

than the ultimate strength of the original design.

450-6Forms

450-6.1General: Use metal side and bottom forms, unless otherwise specified in the

Contract Documents. For members with special shapes such as corner sheet piles, wood forms

are permitted. Slab beams, slab units and sheet piles may be cast on concrete surfaces meeting

the profile dimensional tolerances of 450-6.3. Apply release agents in accordance with the

manufacturer’s recommendations. Liquid membrane curing compounds may be used to prevent

bonding of slab products and sheet piles to the existing concrete surface, when applied in two or

more coatings. Ensure the last application of liquid membrane is applied immediately before

placement of the slab or sheet pile.

For all beam members, use side forms designed to be removed without damaging

the top flange of the beam. Remove the forms horizontally away from the beam by a method that

prevents any contact of the form with the top flange after release of the form. Do not subject the

top flange to any vertical force at any time. Include the form details and method of removal in

the Producer QC Plan.

For all Florida I-Beams, use forms that do not have more than two horizontal

joints.

Use void forms of a type for which service adequacy has been demonstrated,

having sufficient strength to provide stability during handling and placing and to withstand 496FY 2023-24Return to Table of Contents

hydrostatic pressures and other forces imposed upon them during concrete placement. Use form

material that is neutral with respect to the generation of products harmful to the physical and

structural properties of the concrete. Ensure that the presence of the form materials does not

cause any detrimental effect to the concrete or other materials within the member. Positively vent

all voids to the outside of the member. For end headers and inside forms, other materials capable

of resisting the pressure from concrete are permitted, except that end headers used with CFRP

strands must be either timber headers or steel headers with rubber grommets to protect the CFRP

strands from damage.

Use end headers so designed that they can be placed and maintained in correct

position between the side forms. Hold the headers in place with devices capable of being

removed or loosened after the concrete has attained its initial set allowing free form expansion

during curing methods that involve heat. Use end headers with openings conforming to the

prestressing strand pattern to permit passage of the prestressing strand. Locate the openings

accurately within 1/8 inch of planned location of prestressing strand elements.

Construct circular openings for strands a maximum of 1/4 inch larger than the

nominal strand diameter. Construct square or rectangular openings a maximum of 1/4 inch

larger, horizontally and vertically, than the nominal strand diameter. Ensure that all headers are

mortar tight.

450-6.2Supports: Use forms of sufficient thickness, with adequate external bracing and

stiffeners, which are anchored to withstand the forces due to placement and vibration of concrete.

Ensure that joints in forms are mortar tight. Support bottom forms on concrete pallets with metal

stiffeners, wales or shims. Do not use timber elements between the bottom metal form and

concrete pallets.

450-6.3Alignment: Make and maintain during their use, forms and centering true to the

shapes and dimensions for the product being produced. Plumb, align, and secure forms for each

product in position before each reuse.

Apply the following tolerances to form alignment and pallets or beds used in

prestressed construction:

a vertical plane within the length of a product) = 1/8 inch,

horizontal plane within the length of a product) = 1/8 inch,

450-6.4End Header Locations:

450-6.4.1 General: Provide a minimum of 18 inches of exposed strands from the

end header to the stressing anchorage for all products. Provide a minimum of 18 inches of

exposed strands between adjacent ends of all products except 24-inch square and smaller piles.

Provide a minimum of 6 inches of exposed strands between adjacent ends of 24-inch square and

smaller piles.

450-6.4.2 Cold Weather: Provide a distance of at least 5 feet from the end header

to the stressing anchorage, when the ambient temperature is expected to be below 55ºF between

the time of tensioning and detensioning. When the ambient temperature is expected to be below

55ºF between the time of tensioning and detensioning and the product's exposed strands between

the stressing anchorages are not protected, maintain a 25 foot minimum free length of stressed

strands, between the end header and the stressing anchorage at each end of a bed line. When cold 497FY 2023-24Return to Table of Contents

weather concrete conditions as specified in 450-10.1 are in effect, protect all exposed strands

between stressing anchorages regardless of length. When the products and strands between

stressing anchorages are protected, provide protection adequate to maintain the ambient

temperature of the air around the strands at or greater than 55ºF until the products are

detensioned or 24 hours after placing concrete, whichever is less.

450-6.5Surface Conditions: Use clean, rust free form surfaces against which concrete is

to be cast. Inspect forms and, if necessary, recondition them.

450-6.6Form Ties: Ensure that no form wires or metal pieces are left within 2 inches of

the surface of the finished concrete.

450-6.7Corners, Angles and Joints: Ensure corners and angles are chamfered, mitered,

or rounded with a radius of 3/4 inch, unless otherwise specified or shown in the Plans. Provide

smooth mortar tight joints between panel forms within the alignment tolerances.

450-6.8Form Release Agent: Before placing concrete, treat the facing of all forms with

a form release agent in accordance with the manufacturer’s requirements. Ensure the application

of form release agents does not contaminate prestressing strands and/or reinforcing steel.

450-7Protection and Placement of Prestressing Strand

450-7.1Protection of Prestressing Strand: Maintain and store prestressing steel above

the ground surface on platforms, skids, or other supports, to prevent contamination from below,

and protect them from mechanical injury. Do not use any packaging or wrapping material that

retains moisture at the bottom of the reel. Clean contaminated prestressing strand before use or

otherwise reject it. Handle prestressing strand carefully to prevent nicks or kinks. Do not expose

steel prestressing strand to temperatures greater than 165ºF at any time. Do not expose CRFP

prestressing strand to temperatures greater than 120°F at any time. Do not use arc welding

equipment, including welding electrode lines, within 2 feet of prestressing strand. Do not

perform welding on forms that have been set in place after the prestressing strand is placed in the

bed. Reject prestressing strand that has sustained any physical damage at any time.

450-7.2Placing Prestressing Strand: Use care during placement of prestressing strand

to avoid physical damage and contamination. Reject damaged strands. Do not use prestressing

strand containing nicks, kinks, or former chuck grip marks. Do not use prestressing strand

showing evidence of scale formation or which has become pitted. Remove and replace any

damaged prestressing strand in the bed.

450-7.3Cleanliness of Prestressing Strand: Inspect the prestressing strand for any

evidence of contamination. Use strand that is free of deleterious materials such as grease, oil,

wax, dirt, paint (except that used for marking identification) or other similar contaminants.

Remove any contaminants detected from the strand before proceeding with fabrication activities.

Rust on prestressing steel that can be removed by light rubbing is acceptable. Streaks or spots

which may remain after rust removal are acceptable if no pitting is present.

450-7.4Debonded Strands: Install debonding material (sheathing) according to the

prestressing strand locations and lengths shown in the Plans, and manufacturer’s instructions,

except as modified herein. Do not install sheathing over the full length of a product. Extend the

sheathing through the header. Tape and tie the sheathing at the terminus located at the inside of

the member. The tape must be strong enough to hold the sheathing closed.

Use non-slit tubular or two-part sheathing that is high-density plastic. The

sheathing must have a minimum wall thickness of 0.025 inch, and an inside diameter exceeding

the maximum outside diameter of the strand by 0.020 inch to 0.150 inch. Tape the entire length 498FY 2023-24Return to Table of Contents

of seams to ensure mortar tightness when using two-part sheathing. The sheathing and tape must

not react with concrete, coating, steel, or FRP components.

Slit tubular sheathing may be used to repair minor defects such as breakages or

punctures in non-slit tubular sheathing, rectifying an improperly debonded strand, or incorrect

debonded length of a strand. Tape the entire length of the slit tubular sheathing seam and tie the

ends to ensure mortar tightness.

450-8Tensioning Equipment and Operations

450-8.1Equipment: Use a hydraulic jacking system that is adjustable to the automatic

application and sustaining of a predetermined load, together with a pressure transducer or load

cell built into the hydraulic system. Connect such pressure gage or transducer to a dial or digital

readout and printer (manual recording of the tensioning operations is permitted) which will

provide an instantaneous readout and record of the applied load in pounds. Use a jacking system

with the capacity to induce the required load. Base the use of this system on demonstrated

accuracy and repeatability of plus or minus 2% of anticipated load verified through comparison

with loads indicated by an independent load cell.

Calibrate all jacking systems before using and repeat calibration at intervals not

exceeding 12 months. Calibrate and recalibrate in accordance with the equipment manufacturer’s

recommendations, by qualified calibration agency or by plant personnel under the supervision of

a Specialty Engineer.

Calibrate gages, jacks and pumps as a system in the same manner they are used in

tensioning operations with the cylinder extension in the approximate position that it will be in

actual use at final jacking force. In multi-strand tensioning systems, gages may be calibrated

against a master gage of known accuracy, provided that the other units of the system are

calibrated against the same master gage. Ensure calibrations cover the load ranges that will be

used during production. Verify the accuracy setting of the automatic cutoff valves by running the

desired cutoff load. Ensure a certified calibration curve accompanies each tensioning system.

Load readings can be used directly if the calibration determines a reading is within plus or minus

2% tolerance of anticipated load. Ensure calibration of load cells or proving rings used to

calibrate jacking systems are on compression force testing equipment that has been calibrated in

accordance with ASTM E74.

When any jack or gage appears to be giving erratic results, or if the jack force and

elongation do not compare within specified limits and differences cannot be justified while work

is in progress, recalibrate the equipment. Also verify the accuracy of the equipment after internal

jacking system repairs or when gage and jacking units are switched.

Calibrate or recalibrate in accordance with ASTM E4 using equipment that is

calibrated in accordance with ASTM E74. After calibration or recalibration is completed, prepare

a certificate and have it signed by the person responsible for the verifications as outlined in

ASTM E4 and ASTM E74. Ensure that the calibration report includes, the serial number of the

equipment that is calibrated, calibration chart in a graph or tabular form, calibration date,

temperature, full range of readings before and after calibration, National Institute of Standards

and Technology’s (NIST’s) traceable number of calibration device, method of calibration,

calibration agency, and laboratory or Engineer supervising the calibration.

Verify the accuracy of the jacking and recording system a minimum of once each

week during tensioning operations by either an independently calibrated load cell, or by

comparison with calculated strand elongation. When weekly verification is to be performed by

comparison with calculated strand elongation, check a minimum of ten strands and the difference 499FY 2023-24Return to Table of Contents

in the indicated load and the load determined from the elongation must agree within 5% of the

computed theoretical load values. If the differences are greater than 5%, suspend the tensioning

operation, evaluate the tensioning operation by qualified personnel, and correct any deficiencies

before proceeding.

When weekly verification is done by load cell, perform a minimum of five spot

checks to the maximum anticipated load. Use a load cell or proving ring calibrated in accordance

with ASTM E74 and the accuracy of the force must be traceable to NIST. Maintain records of

readings obtained from the force recording system and verifying standard. Ensure the weekly

verification record includes the serial number of the equipment, verification date, verification

agency, NIST traceable number of calibration standard, and name of the person making the spot

checks. The load reading from the recording system must agree within plus or minus 2% of the

anticipated load indicated by the load cell or proving ring that are calibrated annually.

450-8.2Operations:

450-8.2.1 General: The tensioning operations consist of the application of the

final force or load required by the Plans and with adjustments for abutment rotation, bed

shortening, anchorage header movement, live end seating, dead end seating, splice chuck seating,

friction in the jacking system and any other elements as applicable for the type of bed and

anchorage used. Also, adjust the force when the temperature differential between the ambient

temperature at time of stressing and the expected concrete temperature at time of placement is

greater than 25ºF. Increase the force at the rate of 1% for each 10ºF increment that the ambient

temperature at time of stressing is below the expected concrete temperature at time of placing.

Decrease the force at the rate of 1% for each 10ºF that the ambient temperature at time of

stressing is above the expected concrete temperature at the time of placing. Do not allow the

stress in the steel prestressing strand to exceed 80% of the specified tensile strength of the strand,

after seating. Do not allow the stress in the CFRP prestressing strand to exceed 70% of the

specified tensile strength of the strand, after seating. During each tensioning operation, for the

verification of the live and dead end seating, check the seating of at least 4 strands or a minimum

of 10% of the total number of strands, whichever is greater. Maintain a record of the tensioning

operation.

Compensation for temperature differential and abutment rotation are not

required for self-stressing beds. However, adjust the final load for the effects of bed shortening

due to the load from all the strands.

If the placement of concrete is delayed for more than seven calendar days

after the completion of the stressing operation, check and adjust the final strand load as necessary

before placement of concrete and maintain a record of the stressing operation.

Accomplish tensioning by either single strand tensioning or multiple

strand tensioning, and ensure that it is symmetrical about the vertical axis of the product.

Tensioning methods, in general, consist of tensioning to the required loads indicated by the

jacking system, or tensioning to the required load while monitoring the elongation of the

prestressing strand.

Production personnel will perform tensioning operations under

supervision of a QC Inspector/Technician in accordance with Section 105 for prestressed

concrete plant quality control personnel, or certified personnel may perform tensioning

operations directly.

450-8.2.2 Single Straight Strand Tensioning: Apply an initial force of 5% to

25% of the final force to eliminate slack in the system. When single straight strand tensioning is 500FY 2023-24Return to Table of Contents

used, tension the prestressing strand until the required final force is attained. Measure and record

the force and elongation.

450-8.2.3 Multiple Straight Strand Tensioning: Apply the initial uniform

tensioning load to each individual strand before the application of full tensioning load to the

group of strands. The amount of the initial load will be influenced by the length of the casting

bed and the size of strands in the group to be tensioned. The minimum initial tensioning load will

be 5% of the required final load. Increase the magnitude of this load if deemed necessary but do

not allow it to exceed 25% of the required final load. Then tension the strands by multiple strand

tensioning to final load by pulling to elongation and checking against the jack load. Allow the

required elongation to control the tensioning. The actual jack load must agree within 5% of the

required load.

For uniform application of load to strands, the face of anchorage at final

load must be in a plane parallel to its position under initial load. Verify this by measurement of

movement on opposite sides of the anchorage and check its plumb position before and after

application of the final load. During tensioning, allow the anchorage to move without restraint.

450-8.2.4 Draped Strand Tensioning: Tension draped strands by either partial

tensioning and subsequent strains or by final tensioning in draped position.

Partial stressing and subsequent strains applies when the strands are

tensioned through a combination of applied jack loads and strand uplift. To verify the final force,

place a load cell between the tensioning anchorage and anchor chucks at the dead end on at least

two draped strands. Other methods as approved by the Engineer may be used to verify the final

force in the dead end. Apply an initial force of 5% to 25% of the final force to eliminate slack in

the system. After application of the initial force, establish reference marks for measuring

elongation. Apply a pre-calculated jacking force and measure elongations on a minimum of four

strands. The average measured elongation must agree within 5% of the theoretical elongation for

strand force measured by jack load, or the factors contributing to the difference must be

identified and corrected before proceeding. Allow the load indicated by the jacking system to

control the tensioning for the pre-calculated load. Obtain the required final force by lifting or

depressing the strand simultaneously at all pickup or hold down points or in an approved

sequence as shown on the shop drawings. On each different bed setup, after lifting or depressing

the strands to their final position, check the final force at the dead end of at least two strands on

the bed. If the load is below the required tensioning force by more than 5%, adjust it to the final

load.

When the final stressing is performed in the draped position, apply the

tensioning load in two increments with the tendons being held in their draped positions. To

verify the final force, place a load cell between the tensioning anchorage and anchor chucks at

the dead end on at least two draped strands. Other methods as approved by the Engineer may be

used to verify the final force in the dead end. Bring each strand to an initial tension of 5% to 25%

of the final load before the application of the required final load. After application of the initial

load, establish reference marks for measuring elongation. Then tension the strands to final load

and measure the elongation. Allow the load indicated by the jacking system to control the

tensioning for the initial and final loads. The measured elongation must agree within 5% of the

theoretical elongation for the strand force measured by jack load, or the factors contributing to

the difference must be identified and corrected before proceeding. When the jacking is

performed at one end of the bed, check the applied load on two draped strands at the other end of 501FY 2023-24Return to Table of Contents

the bed. If the load on the end opposite the jacking end is below the required value by more than

5%, adjust the load to the required final load.

450-8.2.5 Wire Breakage:

450-8.2.5.1 Steel Prestressing Strand: Limit wire breakage to 2% of the

total area of the strands in any product and verify that breakage is not indicative of a more

extensive distress condition, otherwise reject the defective strand. Replace individual strands

with more than one wire failure.

450-8.2.5.2 Fiber Reinforced Polymer (FRP) Prestressing Strand:

Replace individual strands with any wire failure.

450-8.2.6 Position of Prestressing Strand: Position prestressing strand as shown

in the Plans within the tolerances allowed in 450-2.3. Fix the required vertical and horizontal

position of each prestressing strand at the ends of each product and at intervals within each

product not exceeding 30 feet. Use the method of fixing the prestressing strand shown in the

Producer QC Plan. When blocks are to be used for supporting prestressing strand, use those cast

from concrete of the same mix design as used in the prestressed product. Stagger the location of

blocks with an offset of 12 inches or greater and do not stack them.

450-9Placement of Reinforcing Bars and Other Embedded Materials

450-9.1Reinforcing Bars and Supports: Tie and/or support in position all reinforcing

steel in each product with other reinforcing bars in a manner that will accurately position the

reinforcing bars throughout the fabrication process. Use types of ties and methods of tying

recommended by the CRSI, including lacing. Do not tie reinforcing bars to debonded

prestressing strands within the limits of the sheathing material.

Tie or lace beam stirrup bars at a minimum of three points. Tie reinforcing bars,

other than stirrup bars in beam ends, at a minimum of every other intersection. Either tie or lace

spirals in piling at all four corners in the 1 inch pitch area, at the top corners and bottom center in

the 3 inch pitch area, and at the top corners in the center area. Tie the bottom center in the pile

center area as necessary to maintain concrete cover. Bend all ties away from the form surface to

provide maximum concrete cover.

When shown in the Plans, weld reinforcing steel in accordance with the

requirements of AWS Structural Welding Code D 1.4. Do not weld in the prestressing bed.

450-9.2Other Embedded Materials:

450-9.2.1 Inserts and Lifting Devices:

450-9.2.1.1 Placement: Locate inserts and lifting devices in accordance

with the tolerances listed in 450-2.3. For stainless-steel or FRP reinforced products, use only non-

metallic or stainless-steel (Type 304 or 316) inserts and lifting devices.

450-9.2.1.2 Corrosion Protection: Provide corrosion protection for

embedded metal lifting devices that would remain exposed after lifting operations are complete

as indicated below:

epoxy compound meeting the requirements of Section 926 for a minimum distance of 2 inches

beyond the perimeter of the device. If the block-out extends less than 2 inches beyond the

perimeter of the device, extend the epoxy compound beyond the block-out along the concrete

surface.

back to a minimum depth of 1 inch below the concrete surface and patch with a Type F epoxy

compound meeting the requirements of Section 926. 502FY 2023-24Return to Table of Contents

If Type 304 or 316 stainless steel lifting devices are used, non-

shrink grout meeting the requirements of Section 934 may be used to backfill the block-out

within its limits.

For all square prestressed piling, concrete sheet piling and concrete

poles, cut and patch lifting devices before transporting from the casting yard.

450-9.2.2 Placement of Bearing Assemblies: Set bearing assemblies designed to

transmit reaction forces to the concrete in the position shown in the Plans. Place bearing plate

assemblies or shoes which are to be cast in a product within appropriate tolerances as provided in

450-2.3. Check the assemblies for position after stripping from the forms.

450-10Concrete Operations

450-10.1Temperature Restrictions:

450-10.1.1 Cold Weather Concreting: When the temperature of the surrounding

air is expected to be below 40ºF within 24 hours after placing concrete, the temperature of the

plastic concrete as placed must be 55ºF or greater. Maintain the temperature of the concrete after

placement at or above 55ºF for the first 24 hours or until detensioning, whichever occurs first.

For piles and other members with a minimum section dimension of 12 inches or more, maintain

the temperature of the concrete after placement at or above 50°F for the first 24 hours or until

detensioning, whichever occurs first. Make arrangements for heating, covering, insulating or

housing the concrete work in advance of placement and maintain the required temperature

without adversely affecting the concrete due to concentration of heat. Do not use direct fired

heaters during the first 24 hours after concrete placement, unless actions are taken to prevent

exposure of the concrete to exhaust gases which contain carbon dioxide. Continuously monitor

the temperature of the concrete or the ambient air around the product until the product is

detensioned. Monitor by the use of thermocouples located in the product cross-section or

temperature recording devices located under the enclosure. Provide one thermocouple or

temperature recording device for each 200 feet of bed length or part thereof. Locate the

thermocouples within the products cross-section as shown in the Producer QC Plan or as

approved by the Engineer. Record the monitored temperatures determined by each

thermocouple. Review the recorded temperatures to ensure that they are within the specified

limits. Initially calibrate recording devices or thermocouples and recalibrate them at least

annually in accordance with the manufacturer’s recommendations.

450-10.1.2 Hot Weather Concreting: Meet the requirements of Section 346 for

temperature requirements and special measures for mixing concrete in hot weather.

Apply mist of water to prestressing strands, steel reinforcing, FRP

reinforcing, and steel forms just before placing the concrete when the hot weather concreting

special measures are in effect and the temperature of steel forms or reinforcing steel is greater

than 120ºF.

450-10.2Protection of Concrete from Adverse Conditions or Weather: Have

protection materials available before the concrete placement begins to cover the products in the

event of rain or other adverse conditions during the placement of concrete. Protection materials

may be tarps, curing blankets, or other impervious material that will not puncture when placed

over protruding reinforcing and/or form elements. Include the method and materials for

protection in the Producer QC Plan.

450-10.3Concrete Placement:

503FY 2023-24Return to Table of Contents

450-10.3.1 General: Check forms, reinforcing bars, prestressing strand, vent

pipes, anchorages and other embedded items for compliance with the Contract Documents before

placing concrete. Place concrete in accordance with 400-7, except as modified herein.

For concrete operations conducted at night, provide enough lighting to

allow visual inspection of the interior of the forms during the complete concrete placement

operation.

Convey concrete by the use of buckets, conveyors, pumps, troughs, or

other equipment specifically designed for concrete conveyance, provided the placement method

consistently produces quality concrete with no segregation or separation of the mix. Locate the

concrete conveyance equipment within 12 inches of the top of the forms or surface of the

concrete to minimize the free fall of the concrete.

Multiple placements may be used within a bedline, provided compliance

with 450-11.1 is maintained.

450-10.3.2 Requirements for Successive Layers: Except for self-consolidating

concrete (SCC), place concrete as described in 450-10.3.2.1 through 450-10.3.2.5 as shown in

the Producer QC Plan or as approved in writing by the Engineer.

In any progressive concrete placement operation, do not allow the time

between successive placements onto previously placed concrete to exceed 20 minutes, unless the

previously placed concrete has not yet stiffened, as evidenced by the continued effective use of

vibration.

450-10.3.2.1 AASHTO Type II, Florida I-Beam 36 and Double T-

Beams, Piling, Slab Beams and Precast Slab Units (Except Voided Piling and Slabs): Place

concrete in one or more layers or lifts. If more than one layer is used for Double T-Beams, end

the first layer such that the top of the concrete is slightly below the bottom of the flange.

end the first layer such that the top of the concrete is slightly below the bottom of the flange.

450-10.3.2.2 AASHTO Type III, Type IV and Florida I-Beams 45 and

54 and Voided Units (Slabs and Piling): Place concrete in a minimum of two horizontal layers.

The thickness of the first layer will be such that the top of the concrete is just above the top of

the bottom flange. In voided units, end the first layer slightly above the middle height of the

void.

450-10.3.2.3 All Beams 63 Inches or Deeper: Place concrete in a

minimum of three horizontal layers. The thickness of the first layer will be such that the top of

the concrete is slightly above the top of the bottom flange. The thickness of the second layer will

be such that the top of the concrete is slightly above the bottom of the top flange.

450-10.3.2.4 Pretensioned I-Beams Containing Longitudinal Post-

Tensioning Ducts: Place concrete in one continuous lift beginning in the end block zone and

progressing to the other end. Do not allow the progression of the concrete placement to proceed

until previously placed concrete is properly consolidated, and the rate of advancement equals the

ability to fill the forms. In progression of the placement, deposit concrete within the forms on the

surface of previously placed concrete.

450-10.3.2.5 Florida U-Beams: Place the concrete in Florida U-Beams in

a minimum of two horizontal layers. The thickness of the first layer shall be such that the top of

the concrete is above the top of the bottom flange.

450-10.4Vibration of Concrete: Except for SCC, consolidate concrete in steel

reinforced products by internal or external vibration, or combination of these methods. For SCC,

meet the requirements of Section 8.4 of the Materials Manual for production batch verification. 504FY 2023-24Return to Table of Contents

For CFRP strand reinforced products, use SCC without the use of vibration. If further

consolidation is needed, manual rodding is permitted.

Design external form vibrators for the specific use. Design forms used in

conjunction with external vibration and build them to effectively transmit vibration to the

concrete mass. Mount and operate form vibrators in compliance with the vibrator manufacturer’s

recommendations, a copy of which must be on file at the plant. Secure vibrators to the form

mounts by positive locking devices so that maximum vibration is transmitted into the form.

Modify or replace external form vibrator systems that are demonstrated to be ineffective. Operate

vibrators at each mount location for the time necessary for complete concrete consolidation. Do

not allow progressive points of vibration to exceed twice the visually effective radius of

vibration. Keep forms equipped with external vibrators clean, and free of any buildup of

hardened concrete.

Ensure internal vibrators are available before concrete placement is started. Use

an internal vibrator with a head of such size that proper vibration of the concrete will be secured

without causing movement of the prestressing strand or reinforcing bars. The vibrating frequency

range must be 8,000 to 15,000 impulses per minute. Have at least one standby vibrator available

on-site. Insert the vibrator in the concrete at points spaced to ensure uniform vibration of the

entire mass of the concrete. Do not allow points of insertions to be further apart than the radius

over which the vibrator is visibly effective. Allow the vibrator to sink into the concrete by its

own weight and penetrate into the underlying layers sufficiently so that the layers are thoroughly

consolidated. After the concrete is thoroughly consolidated, slowly withdraw the vibrator to

avoid formation of holes.

Revise the existing placement and consolidation procedure to improve the

consolidation of the concrete, if the existing placement and consolidation procedure has

produced unacceptable surface defects such as honeycombing, aggregate or mortar pockets, or

excessive air bubbles.

450-10.5Finishing:

450-10.5.1 General: When concrete incorporating silica fume is used, screed and

finish with a continuous water fog mist maintained above the concrete. Do not apply the mist

directly toward the concrete. A monomolecular finishing aid approved by the Engineer may be

applied in accordance with the manufacturer’s recommendation.

450-10.5.2 Beams: Rough float the top surface of the beam and then scrub it

transversely with a coarse brush or metal tine to produce a roughened surface for bonding. For

the other external surfaces of prestressed beams, unless otherwise specified, apply a General

Surface Finish in accordance with 400-15.1. Remove mortar leakage and stains to produce

beams with a uniform appearance.

450-10.5.3 Piling: Unless a Class 5 Applied Finish Coating is specified, apply a

general surface finish as specified in Section 400 to pile surfaces, except that pointing with

mortar will not be required for chips and bug holes with a depth less than 1/4 inch and a diameter

of less than 3/4 inch. All other general surface finish requirements will apply, including the

pointing of material form tie cavities with mortar. Surface finish deficiencies that meet the

definition of noncomplying prestressed products must be corrected in accordance with 450-12.

Miter or round the top corners similar to the corner radius of the pile forms. Surfaces exposed

during casting must have a steel trowel finish.

450-10.5.4 Slabs and Double-T Beams: When the Plans show the top surface of

prestress slab units, slab beams, or Double T-Beams units to be the riding surface, apply a Class 505FY 2023-24Return to Table of Contents

4 floor finish in accordance with Section 400. When the Plans show the surface to be overlaid

with asphalt or concrete, rough float the top surface and then scrub it transversely with a coarse

brush to remove all laitance and to produce a roughened surface for bonding. For the other

external surfaces of slabs and Double T-beams, unless otherwise specified, apply a General

Surface Finish in accordance with 400-15.1.

450-10.6Curing: Cure prestressed concrete for a minimum duration of 72 hours. If

forms are loosened upon setting of concrete and/or removed before the 72 hour curing period is

complete, expand the curing to cover the newly exposed surfaces by either coating with curing

compound or extending the continuous moist cure area. Maintain concrete surface moisture at all

times until curing is begun. If a water sheen is not present, apply supplemental moisture by

misting or prevent water sheen loss on flat work by use of an evaporation retarder.

After the finishing operations have been completed and as soon as the concrete

has hardened sufficiently to permit the application of curing material without marring the

exposed surface, cover the exposed surfaces of all prestressed concrete products by one of the

following procedures or other alternate curing methods. Alternate curing methods must be

approved by the Engineer. Base alternate curing methods upon a demonstrated ability to retain

surface moisture of the concrete and to control curing temperatures within acceptable limits.

Discontinue use of any alternate curing method other than those included herein upon any

indication of noncompliance with this Specification.

450-10.6.1 Continuous Moisture: Place burlap on the surface and keep it

continuously saturated for the curing period by means of soil soakers, leaking pipes, or automatic

sprinklers. Do not apply moisture manually. If side forms are removed during the curing period,

extend the burlap to completely shield the sides of the product. Water flow may be metered to

cycle repetitively for five minutes on and five minutes off during the 72 hour curing period.

When it is not practical to apply moisture or curing compound inside the voided piles, cover their

ends with wet burlap to prevent moisture loss.

450-10.6.2 Membrane Curing Compound: Apply a Type 2 white pigmented

curing compound to all surfaces in a single-coat, continuous operation, at a uniform coverage as

recommended by the manufacturer but not less than 1 gallon per 150 square feet. Apply the

curing compound on the concrete surfaces that are still damp but have no free standing water.

Allow surfaces covered by the membrane curing compound to remain undisturbed for the curing

period. Recoat any cracks or other defects in the membrane seal which are detected during the

curing period upon discovery.

If side forms are loosened during the curing period, remove them at that

time and immediately coat the formed surfaces with either a Type 1 clear, or Type 2 white

pigmented membrane curing compound. Maintain the surface seal for the remainder of the

curing period. Bottom surfaces must be similarly coated after removal of the forms. Remove

membrane curing compound to applied surfaces of concrete products to which other concrete is

to be bonded by sandblasting or water-blasting until all traces of membrane curing compound are

removed.

When the curing compound is applied by spraying, use a compressor

driven sprayer of sufficient size to provide uniform spray at the nozzle. Keep all nozzles clean to

ensure a uniform application of compound. For compressor driven sprayers, provide a calibrated

reservoir which will allow the quantity of applied materials to be accurately determined.

Maintain standby equipment in case of mechanical failure. If a mechanical failure occurs, a hand

held pump-up sprayer may be used to apply curing compound to the remainder of the products 506FY 2023-24Return to Table of Contents

cast in the day’s production. Suspend additional concrete placements until the mechanical

sprayer is functioning properly.

450-10.6.3 Curing Blankets: Curing blankets may be used for curing the top

surfaces of products. Do not use curing blankets which are torn or punctured. Securely fasten

edges to provide as tight a seal as practical. Allow curing blankets to remain in place for the

curing period. Should the system fail to maintain a moist condition on the concrete surface,

discontinue the use of curing blankets and take immediate corrective action to prevent further

loss of concrete moisture.

450-10.7Accelerated Curing:

450-10.7.1 General: Use low-pressure steam curing, radiant heat curing or

continuous moisture and heat curing. Submit steam and/or radiant heat curing procedures for

CFRP strand products for approval. If accelerated curing is completed before the curing period

has elapsed, continue curing for the remaining part of the curing period in accordance with one

of the curing methods above.

If accelerated curing is used, furnish and use temperature recording

devices that will provide accurate, continuous, and permanent records of the time and

temperature relationship of the enclosure and concrete throughout the entire curing period. Place

the temperature recording sensors at a minimum of two locations, spaced approximately at or

near the third point of bed length, to measure the temperatures of the enclosure and concrete.

Initially calibrate recording thermometers and recalibrate them at least annually in accordance

with manufacturer’s recommendations. Place the sensors at the center of gravity of the bottom

flanges for beams. Place the sensors at the center of gravity of the cross sections perpendicular to

the length for solid piles or poles, and at the midpoint of the wall thickness for voided piles or

poles.

When the ambient air temperature is equal to or higher than 50ºF, start the

accelerated curing by supplying or retaining moisture and the application of the heat, following

the initial set period of concrete. Determine the initial set time in accordance with ASTM C403.

During the application of heat, do not allow the temperature rise in the concrete product to

exceed 36ºF per hour. The maximum curing temperature of the enclosure or concrete must not

exceed 150ºF. Maintain the maximum curing temperature uniform throughout the enclosure,

with variation of not more than 20ºF from the maximum peak temperature until concrete reaches

the required release strength. Allow the concrete element to cool gradually at the maximum

cooling rate of 50ºF per hour and continue the cooling at this rate until the concrete temperature

is 40ºF or less above the ambient temperature outside the curing enclosure.

When the ambient air temperature is below 50ºF cure the concrete in two

stages. Start the accelerated curing of the first stage during the preset period by applying heat to

increase the temperature of concrete at the maximum rate of 10ºF per hour. The total temperature

gain of concrete during the initial set period cannot exceed 40ºF higher than the placement

temperature, or 104ºF, whichever is less. Upon obtaining the initial set, continue curing as stated

above for ambient temperature of 50ºF or higher. To prevent moisture loss on exposed surfaces

during the preheating period, cover products as soon as possible after casting or keep the exposed

surfaces wet by misting or wet blankets. Use enclosures for heat curing that allow free

circulation of heat about the product and that are constructed to contain the heat with minimum

moisture loss. The use of tarpaulins or similar flexible covers may be used provided they are kept

in good repair and secured in such a manner to prevent the loss of heat and moisture. Use

enclosures that cover the entire bed from stressing abutment to stressing abutment, including all 507FY 2023-24Return to Table of Contents

exposed stranding, except when using CFRP strands. When using CFRP strands, follow the

manufacturer’s instructions.

450-10.7.2 Low-Pressure Steam: The steam must be in a saturated condition. Do

not allow steam jets to impinge directly on the concrete, test cylinders, or forms. Cover control

cylinders to prevent moisture loss and place them in a location where the temperature is

representative of the average temperature of the enclosure.

450-10.7.3 Curing with Radiant Heat: Apply radiant heat by means of pipe

circulating steam, hot oil or hot water, or by electric heating elements. To prevent moisture loss

during curing, keep the exposed surfaces wet by misting or wet blankets.

450-10.7.4 Continuous Moisture and Heat: This method consists of heating the

casting beds in combination with the continuous moisture method described above. Do not allow

the heating elements to come in direct contact with the concrete or the forms. The initial

covering of burlap and the continuous application of moisture will be as described in 450-10.6.1.

An auxiliary cover in addition to the burlap for retention of the heat will be required over the

entire casting bed. Support this cover a sufficient distance above the product being cured to allow

circulation of the heat.

450-10.8Curing Requirements for Silica Fume Concrete: Use either a 72 hour

continuous moisture curing or a (12-24) hour low-pressure steam curing in accordance with

450-10.7. Upon completion of the low-pressure steam curing, continue curing for the remaining

part of the 72 hour curing period by application of the curing compound, continuous moisture

curing, or use of the curing blankets.

If 72 hour continuous moisture is used, begin curing silica fume concrete

immediately after the finishing operation is complete and keep a film of water on the surface by

misting until the curing blankets are in place. No substitution of alternative methods nor

reduction in the time period is allowed. After completion of the 72 hour curing period, apply a

membrane curing compound to all concrete surfaces. Apply curing compound according to

450-10.6.

450-10.9Form Removal: Do not remove 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, Florida I-Beams, and Bulb I-Beams, do not remove the forms supporting the top flange

concrete sooner than 12 hours after casting unless the release strength has been reached.

450-11Detensioning

450-11.1General: The required concrete strength at which the prestressing force may be

transferred to the concrete in a product will be a minimum of 4,000 psi, unless specified

otherwise in the Plans. Verify the release strength by compressive strength cylinder tests or other

approved means, no later than 24 hours after casting and every 24 hours thereafter until release

strength is developed.

In lieu of every 24 hour testing, estimate the strength development of concrete

using the maturity method in accordance with ASTM C1074, the pulse velocity method in

accordance with ASTM C597, or any other nondestructive test method acceptable to the

Engineer, until the time of the detensioning.

Before detensioning, verify the concrete release strength by testing the

compressive strength test cylinders. Make a minimum of two compressive strength release test

cylinders daily for each individual mix or for each LOT, or fraction thereof, of a given concrete

mix design where the daily consumption exceeds this volume or when non-continuous batching

or dissimilar curing is used. The release strength test, representing the LOT, is the average 508FY 2023-24Return to Table of Contents

compressive strength of two test cylinders, cured under conditions similar to the product or

match-cured test specimens, which are match cured until the time of release.

For products cured using accelerated curing, release the prestressing force

immediately after terminating the accelerated curing process. After the detensioning operation is

completed, continue to 72 hour curing period using one of the methods listed in 450-10.6. For

products cured using methods other than accelerated curing, release the prestressing force within

a detensioning time limit, not to exceed five calendar days after the verification of release

strength by compressive strength cylinder test or other approved strength gain monitoring

system.

For all products in a casting line, use the same test method for determining their

release strengths. Ensure the detensioning time limit is included in the Producer QC Plan. Cure

concrete cylinders used for detensioning strength tests in the same manner and location as the

prestressed concrete products they represent.

For I-Beams, when side forms are loosened upon setting of concrete or removed

before the 72 hour curing period is complete, the top flange dormant strands may be released

after the concrete reaches a compressive strength of 2,000 psi.

Perform detensioning operations under the supervision of personnel possessing a

certificate of completion of PCI Quality Control Personnel Certification Level II, and

Section 450 Specification examination.

450-11.2Method of Stress Transfer: In all detensioning operations, keep the

prestressing forces nearly symmetrical about the vertical axis of the product and apply them in a

manner that will minimize sudden shock or loading. Remove or loosen forms, ties, inserts, or

other devices that would restrict longitudinal movement of the products along the bed. Release

hold-downs for products with draped strands in a sequence as shown in the Plans or Producer QC

Plan. Cut dormant strands (partially tensioned strands) before releasing any fully tensioned

strands. Release fully bonded strands next, beginning with the lowest row and moving upwards,

followed progressively by strands having the minimum length of tubular sheathing through to

those strands having the maximum length of tubular sheathing.

Transfer prestressing forces to the concrete by either single strand release or

multiple strand release.

450-11.3Single Strand Detensioning: Detension the strand by using a low-oxygen

flame in accordance with a pattern and schedule provided in the approved shop drawings, or

Producer QC Plan, or described in 450-5. Heat with a low-oxygen flame played along the strand

for a minimum of 5 inches. Heat strands in such a manner that the failure of the first wire in each

strand will occur after the torch has been applied for a minimum of five seconds.

Release strands in all prestressed products simultaneously and symmetrically

about the vertical axis at both ends of the bed and at all intermediate points between products to

minimize sliding of products. Strands in piles, sheet piles, slabs, and AASHTO Type II Beams

may be detensioned at the intermediate areas after detensioning both ends.

For CFRP strands coupled with steel strands, detension the steel strands first

using the flame cutting process described above. At intermediate locations where CFRP strands

are continuous between adjacent precast components, flame or shear cutting of the strands is not

allowed.

450-11.4Multiple Strand Detensioning: In this method, detension all strands

simultaneously by hydraulic dejacking. The total force is taken from the header by the jack, then

released gradually. Do not allow the overstress required to loosen the anchoring devices at the 509FY 2023-24Return to Table of Contents

header to exceed the force in the strand by 5%. After detensioning, strands at all points may be

cut progressively from one end of the bed to the other using equipment and methods described

above.

450-11.5Cutting Strands and Bars: Upon completion of the detensioning operation,

cut steel strands to required length, using an oxygen flame or mechanical cutting device. Do not

use electric arc welders to cut bars or steel strands. Upon completion of the detensioning

operation, cut CFRP strands to the required length using a mechanical cutting device. Do not use

flame or shear cutting to cut CFRP strands.

450-11.5.1 Beams: For beam ends that will be permanently encased in concrete

diaphragms, cut strands to 2.5 inches plus or minus 0.5 inch beyond the end of the product or as

specified in the Plans. For beams with ends that will not be encased in permanent concrete

diaphragms, mechanically cut strands a minimum of 1/8 inch below the concrete surface.

450-11.5.2 Piles: Mechanically cut strands flush with the concrete surface. For

top (head) of fender piles and pile ends not embedded under final conditions, burn the strands a

minimum of 1 inch below the concrete surface and clearly mark the pile to identify the top

450-11.5.3 Poles: Mechanically cut strands to a minimum of 1/8 inch below the

concrete surface.

450-11.6Protecting Ends of Strands: Prepare the concrete surfaces and apply Type F-1

epoxy in accordance with the manufacturer’s recommendations.

450-11.6.1 Beam Ends that will not be Permanently Encased in Concrete

Diaphragms:

the cut end of the strands.

clipped and chamfered surfaces) at the applicable time frame below:

days prior to shipping but no later than 50 calendar days after detensioning.

days prior to shipping, or between 42 and 50 calendar days after detensioning, whichever occurs

first.

as follows:

outer stands of the bottom strand group any time after detensioning.

group between 42 and 50 calendar days after detensioning. Ensure that the entire beam end is

fully coated at least 3 calendar days prior to shipping.

Ensure that the first epoxy layer is cured before applying the second layer.

The finished thickness of the epoxy coating must be a minimum of

1/16 inch and form a vertical flat plane without deviations or localized depressions from recessed

strands or other defects.

Ensure that the epoxy coating is cured per the manufacturer’s

recommendations prior to shipping the products.

Any modifications to the time limits above must be approved by the

Engineer. 510FY 2023-24Return to Table of Contents

450-11.6.2 Beam Ends that will be Permanently Encased in Concrete

Diaphragms:

strands with 100% silicone sealant within fourteen calendar days of detensioning, and cure per

the manufacturer’s recommendations.

450-11.6. 3 Piles: Apply epoxy patches to all recessed strands.

450-11.6. 4 Poles: Coat entire face of tip (top) and butt (bottom) ends with epoxy.

450-12Noncomplying Prestressed Products

450-12.1General: When a precast prestressed concrete product does not comply with

the requirements of this Section or is damaged, use the following provisions for evaluating and

dispositioning of deficiencies. However, when precast prestressed concrete products have been

installed, the disposition of concrete cracks shall be in accordance with Section 400. Apply these

provisions in all cases that clearly fall under the circumstances described in Section 400.

Consider situations not covered by these specific circumstances on their individual merits.

Consider and apply the following where practical.

Make all major repairs that require a repair proposal under the observation and the

satisfaction of the QC Manager or designee.

450-12.2Identification of Defects: The QC Manager, or QC inspectors under direction

of the QC Manager, will examine all deficiencies within the time limit specified in 450-2.3 and

450-2.4, to determine the applicable provisions and requirements of this Article and which

course of action is appropriate.

minor defect, as stated 450-12.3, appropriate repairs may be executed in accordance with 450-13.

acceptance, submit a completed Noncomplying Prestressed/Precast Concrete Component Data

Sheet (Form No. 700-030-10) to the Engineer within 30 days of the defect identification.

Submit an Engineering Analysis Scope in accordance with 6-4 for

approval, to address the deficiency. A previously approved Engineering Analysis Report (EAR)

may not be applied to a current major repair without the approval from the original engineer who

signed and sealed the previously approved EAR.

Make major repairs under the observation of and to the satisfaction of the QC

Manager. The Engineer reserves the right to witness the repairs.

The disposition of deficiencies and repair methods provided herein must at no

time, and under no circumstances, be used as an excuse for or applied in such a manner so as to

relieve the Contractor of his responsibility for QC. The number and type of deficiencies

evaluated under this Specification will, however, be used in evaluating the Contractor’s QC.

The Engineer may require a credit on any products with deficiencies that require

an EAR and are accepted for use in the structure. Bear the costs of repairs and any actions taken

to rectify deficiencies at no expense to the Department.

450-12.3Common Defects in Precast Prestressed Concrete Products:

450-12.3.1 Surface Deficiencies: Surface deficiencies are defined below and

include spalls, chips, bug holes, surface porosities, honeycombs, and shallow surface cracks.

Regardless of the types of deficiencies, when the total surface area of all

deficiencies within a single product exceeds 1.0% of the product’s area that will be exposed to

the environment, the deficiencies are considered major. 511FY 2023-24Return to Table of Contents

450-12.3.1.1 Bug Hole: A bug hole is a void caused by air that is

entrapped against the form and that has an area up to 3.0 square inches and a depth up to

1.5 inches. Treat any bug hole with a dimension exceeding either of these dimensions as a

honeycomb. The Engineer will not require repair of any bug hole with a depth less than 0.25 inch

and less than 0.75 inch in diameter, unless otherwise indicated in the Plans or Specifications.

450-12.3.1.2 Spall: A spall is a depression resulting when a fragment is

detached from a larger mass by impact, action of weather, by pressure or by expansion within the

larger mass.

A cosmetic spall is a circular or oval depression not greater than

1.0 inch in depth nor greater than 3.0 square inches in area, and must be repaired in accordance

with 450-13.2.

With the exception of spalls in the bearing areas and edges of the

top flange, a minor spall is defined as a spall not larger than 2.0 square feet and no deeper than

one inch plus the sum of the concrete cover and the diameter of the bar in the first layer of

reinforcing. Repair minor spalls in accordance with 450-13.4.

Spalls located at the edges of the top flange are considered minor

spalls as follows:

coincident spall on the other edge of the top flange, is considered a minor spall if the total

longitudinal length of the defect does not exceed 10 feet and any lateral dimensions of the spall

measured perpendicular to the longitudinal axis of the beam are not greater than 25% of the

width of the top flange.

considered minor spalls if the total length of the defects within both spalls does not exceed 10

feet and any lateral dimensions of the spalls at a given location measured perpendicular to the

longitudinal axis of the beam are not greater than 25% of the width of the top flange.

Spalls are considered major when they are located in the extended

bearing area of the beams as defined in 450-12.3.5, or if any depression exceeds the dimensions

that are described for minor spalls.

450-12.3.1.3 Chip: A chip is the local breaking of the corners or edges of

the concrete with the resulting void containing angular surfaces.

Cosmetic chips are chips where the sum of the two lateral

dimensions perpendicular to the length does not exceed 2.0 inches. Regardless of length, it is not

necessary to repair cosmetic chips except for visually exposed reinforcing steel, prestressing

strand, insert, or weldments surfaces, which may require repair in accordance with 450-13.5.

Minor chips are chips where the sum of the two lateral dimensions

perpendicular to the length exceeds 2.0 inches, but does not exceed 4.0 inches, and with a length

of no more than 12.0 inches. Repair minor chips in accordance with 450-13.5.

Major chips are any chips larger than minor chips. Major chips

require engineering evaluation and disposition in accordance with 450-12.

450-12.3.1.4 Surface Porosity: Surface porosity is considered a minor

defect and is the localized porosity of a formed surface due to medium scaling. Medium scaling

is defined as the loss of surface mortar up to 3/8 inch in depth and exposure of concrete

aggregate. Repair surface porosity in accordance with 450-13.3.

450-12.3.1.5 Honeycombing: Honeycombing is voids in the concrete,

loss of fines or other material from between the aggregate particles, the inclusion of air pockets 512FY 2023-24Return to Table of Contents

between aggregate particles, or larger volumes of lost material. Remove honeycombing in its

entirety to sound concrete before establishing the classification of the defect.

Minor honeycombing is a void no deeper than concrete cover and no

larger than 2.0 square feet in area after the removal of unsound material. Repair minor

honeycombing in accordance with 450-13.6.

Major honeycombing is a void deeper than concrete cover regardless of

the surface area, or shallower but with a surface area greater than 2.0 square feet that results after

the removal of unsound material.

450-12.3.1.6 Shallow Surface Cracks: Shallow surface cracks are

considered a minor defect, and are defined as the separation of the formed or finished surface up

to 0.25 inch in depth.

Remove the affected material and repair the surface in accordance

with 450-13.3.

450-12.3.2 Segregated Appearance in Hardened Concrete: Segregation of

hardened concrete is considered a major defect. When hardened concrete segregation is evident,

evaluate in accordance with FM 5-617.

450-12.3.3 Cold Joints: A cold joint is a plane of weakness in concrete caused by

a batch of concrete setting before the next batch is added, so that the two batches fail to bond. A

cold joint is considered a major defect and requires an EAR.

450-12.3.4 Formed Surface Misshaping: Formed surface misshaping is the

visual and measurable deficiency or excess of material from the specified tolerance on any

surface of a product.

tolerances by grinding in accordance with 450-13.7, or any other means of removal as approved

by the Engineer. Reshape the chamfer if more than 0.25 inch from the cast pile end is removed

and such removal affects the chamfer dimension.

within the tolerances in accordance with 450-13.7.

length, squareness, designated skew, plumbness, and the like by up to twice the specified plus

(+) tolerance may be corrected by grinding to within the allowable tolerance in accordance with

450-13.7. Any deficiency exceeding the specified minus (-) tolerance or twice the specified plus

(+) tolerance will be considered major.

450-12.3.5 Bearing Area Flaws: Consider the bearing area to extend from the

end of the product to 3 inches beyond the edge of the bearing contact area for the full product

width.

Do not allow the bearing plate or bearing area plane of precast prestressed

concrete beam and slab units to deviate from a true plane by more than 1/8 inch when tested in

all directions with a steel straightedge. In the event that a 100% true plane is not achieved, the

Engineer will accept a surface having not less than 80% of its area in a true plane provided the

deviations are evenly distributed. Remove minor convex projections by grinding with an

abrasive stone. The Engineer will accept minor depressions, provided that they amount to not

more than 20% of the bearing area, are evenly distributed over the entire bearing area, and are

not deeper than 1/8 inch.

450-12.3.6 Cracks: A crack may appear before or after detensioning and may or

may not cause separation throughout the product thickness or depth. Identify cracks by the 513FY 2023-24Return to Table of Contents

classifications and locations described below and subject them to the disposition required by the

identified crack.

If the total surface length of all cracks within a single product, regardless

of their width and depth, located between the end zones exceeds one-quarter of the product’s

length, the cracks are considered major. Establish crack sizes subsequent to release of all

pretensioning forces.

The Engineer will reject any pile that is cracked to the point that a

transverse or longitudinal crack extends through the pile, shows failure of the concrete as

indicated by spalling of concrete on the main body of the pile adjacent to the crack, or which in

the opinion of the Engineer will not withstand driving stresses. Occasional hairline surface

cracking caused by shrinkage or tensile stress in the concrete from handling will not be cause for

rejection.

450-12.3.6.1 Locations of Cracks: Regardless of cause and for the

purposes of this Specification, cracks will be identified as occurring in either critical or non-

critical locations of the product in accordance with the following criteria and conditions:

450-12.3.6.1.1 Critical Location Cracks: Critical locations of

cracks are any locations in which a crack would tend to open under stresses occurring at any time

during the service life of the structure, or which may reduce the ultimate capacity or fatigue life

of the product. Specifically, critical locations of cracks are any locations in a product not defined

and not included in 450-12.3.6.1.2 as non-critical. Cracks in critical locations require engineering

evaluation and disposition in accordance with 450-12.

450-12.3.6.1.2 Non-Critical Location Cracks: Non-critical

locations of cracks are defined by the position within a product’s length, the position within a

product’s depth, and the orientation of the crack.

exceeding twice the width of the pile.

(within a distance of three times the depth of the product from the end):

ends in the top flange and web of the product, not in the plane of nor intersecting any row of

prestressing strands, and extending from the end of the product for a length not to exceed the

product’s depth.

not to exceed one-half of the product’s depth after detensioning.

cracks extending through the top flange and web of the product.

of the web and top flange which is not longer than the product’s depth.

cracks at any location.

the product from the end): One horizontal crack at either or both ends and in the top flange of the

product, not in the plane of nor intersecting any row of prestressing strands, and extending from

the end of the product for a length not to exceed half the product’s depth. 514FY 2023-24Return to Table of Contents

cracks extending through the top flange and not exceeding half the web depth of the product.

the web and top flange which is not longer than the product’s depth.

Tensioning Ducts:

the beam from the end): Vertical cracks in the bottom half of the beam within an end zone with

no post-tensioning anchorages and where the post-tensioning ducts are located in the top of the

beam at the location of a permanent substructure support. Horizontal or diagonal cracks at either

or both ends in the top flange and web of the product where no post-tensioning anchorage zone is

present.

Vertical cracks in the web and top flange of the beam provided the beam is to be supported at

each end in its final position in the structure.

the beam’s depth and only at the interface of the web and top flange provided the beam is to be

supported at each end in its final position in the structure.

either or both ends in the top flange and web of the product.

pretensioned concrete beams.

tensioning anchorages: same as pretensioned I-Beams containing longitudinal post-tensioning

ducts. At end of beam adjacent to pier sections: same as for simple span pretensioned concrete

beams.

of the product from the end): One horizontal crack at either or both ends in the top half of the

product, which is not in the plane of nor intersecting any row of prestressing strands, and

extending from the end of the product for a length not to exceed half the product’s depth.

cracks in the top half of the product’s depth.

each crack must be less than twice the base width of the pole, or transverse or diagonal cracks

perpendicular to or at an inclined angle to the longitudinal direction of the pole.

extending across one or two adjacent planes of a square pole, less than 2.0 inches of total length

across all planes.

450-12.3.6.2 Classification and Treatment of Cracks: Cracks in precast

prestressed components, excluding piling, will be identified according to their width, and surface

appearance, and classified as follows: 515FY 2023-24Return to Table of Contents

450-12.3.6.2.1 Cosmetic Cracks: Cracks located in non-critical

locations on product which are less than 0.006 inch wide. Based on the environmental

classification of the site where the product will be located, treat cosmetic cracks as follows:

treat cracks.

apply penetrant sealer in accordance with Section 413.

450-12.3.6.2.2 Minor Cracks: Cracks located in non-critical

locations on products which are between 0.006 and 0.012 inch wide, inclusive. Based on the

environmental classification of the site where the product will be located and the final elevation

of the product on the site, treat minor cracks as follows:

of more than 12 feet above the existing ground level or above mean high water elevation: Do not

treat cracks.

within 12 feet above the existing ground level or above mean high water elevation: Apply a

penetrant sealer on the cracks after detensioning in accordance with Section 413.

of more than 12 feet above the existing ground level or above mean high water elevation: Apply

a penetrant sealer on the cracks after detensioning in accordance with Section 413.

within 12 feet above the existing ground level or above mean high water elevation: Inject epoxy

into the cracks after detensioning in accordance with Section 411.

450-12.3.6.2.3 Major Cracks: Cracks, regardless of

environmental classification, located in critical locations on products or cracks in non-critical

locations of the product that are greater than 0.012 inch wide. Major cracks are considered major

defects and require an EAR in accordance with Section 6 to determine the disposition of the

affected product

450-12.3.6.2.4 Cracks in the Riding Surface: Repair cosmetic

and minor cracks in the top surface of components which will become the riding surface (with no

overlays), once in service, regardless of the environmental classification as follows:

with Section 411, unless the Engineer approves the sealing of cracks with high molecular weight

methacrylate in accordance with Section 413.

penetrant sealer in accordance with Section 413.

450-13Repair Methods and Materials

450-13.1General: Before beginning the repairs of bug holes, spalls, chips, surface

porosity, and honeycomb, remove all laitance, loose material, form oil, curing compound and

any other deleterious matter from the repair area. Repair cosmetic or minor deficiencies by

methods specified herein. Submit alternative repair methods as needed.

For each project, maintain the record of deficiencies and their repair methods.

Ensure the record includes information about product description, unit serial number, date cast, 516FY 2023-24Return to Table of Contents

defect description including dimensions, repair method and materials, defect discovery date, and

signature of producer’s QC Manager indicating concurrence with the information.

Cure repaired surfaces for the full 72 hour curing time or for the curing time as

recommended by the manufacturer of the repair material. Ensure the repaired surfaces have a

surface texture, finish and color which matches the appearance of the unaffected surrounding

area of the product.

450-13.1.1 Product Acceptance on the Project: Use only materials listed on the

Approved Product List (APL),in accordance with the following Sections:

Epoxy Compounds (Type F) ……………….. Section 926

Materials for Concrete Repair………………. Section 930

Non-shrink Grout…………………………… Section 934

450-13.2Cosmetic Surface Filling: Repair areas to be filled with an approved non-

shrink grout or material for concrete repair. Mix, apply, and cure the material in accordance with

the manufacturer’s recommendations. Coating of the prepared surface with epoxy compound

before placement is not required.

450-13.3Surface Restoration: Maintain the surface continuously wet for a minimum of

three hours before application of repair material. Repair areas to be restored with a mortar mix

consisting by volume of one part cement, 2.5 parts sand that will pass a No. 16 sieve, and

sufficient water to produce a viscous slurry mix or repair areas to be restored with an approved

non-shrink grout or material for concrete repair. Mix, apply, and cure the material in accordance

with the manufacturer’s recommendations. Cure areas repaired with a mortar mix in accordance

with 450-10.6. Coating of the prepared surface with epoxy compound before placement is not

required.

450-13.4Cutting and Filling: Carefully cut all feathered edges of the area to be repaired

back perpendicular to (or slightly undercut from) the surface and to the depth of sound concrete

or to a minimum depth of 1/2 inch, whichever is deeper. Coat the prepared surface with an

approved epoxy bonding compound applied in accordance with the manufacturer’s

recommendations. Fill the cutout area with an approved non-shrink grout, material for concrete

repair, or epoxy mortar. Mix, apply, and cure in accordance with the manufacturer’s

recommendations. Firmly consolidate the material in the cutout area.

450-13.5Restoration of Surfaces and Edges: When reinforcement is exposed, remove

concrete from around the items to provide a 1-inch clearance all around. When less than one-half

the reinforcement diameter is exposed, a positive connection utilizing anchor screws may be

proposed in lieu of 1-inch clearance all around. Do not damage the reinforcement. Form surfaces

and edges to the original dimensions and shape of the product. Coat the prepared surface with an

approved epoxy bonding compound applied in accordance with the manufacturer’s

recommendations. Restore surfaces and edges with an approved non-shrink grout, material for

concrete repair, or epoxy mortar. Mix, apply, and cure in accordance with the manufacturer’s

recommendations. Firmly consolidate the material in the area to be repaired. Restore surfaces

and edges to the original dimensions and shape of the product.

450-13.6Removal and Restoration of Unsound Concrete: Carefully cut the area of

unsound concrete to be repaired back perpendicular to (or slightly undercut from) the surface and

to the depth of sound concrete or to a minimum depth of 1 inch, whichever is deeper. When

reinforcement is exposed, remove the concrete from around the items to provide a 1-inch

clearance all around. When less than one-half the reinforcement diameter is exposed, a positive

connection utilizing anchor screws may be proposed in lieu of 1-inch clearance all around. Do 517FY 2023-24Return to Table of Contents

not damage the reinforcement. Coat the prepared surface with an approved epoxy bonding

compound applied in accordance with the manufacturer’s recommendations. Fill the area to be

repaired with an approved non-shrink grout, concrete repair material, or epoxy mortar. Mix,

apply, and cure in accordance with the manufacture’s recommendations. Firmly consolidate the

material in the area to be repaired. Restore surfaces and edges to the original dimensions and

shape of the product.

450-13.7Surface Grinding: Grind off misshaped formed surfaces with an abrasive

stone. Apply two coats of penetrant sealer in accordance with the requirements of Section 413, to

any surfaces which are not subsequently encased in concrete, immediately after grinding has

been accepted. Do not apply a penetrant sealer to any surfaces to be subsequently encased in

concrete.

450-13.8Treatment of Cracks: Treat cracks in accordance with 450-12.3.6

450-14Handling, Storage, Shipping and Erection

450-14.1Handling: All products which are pretensioned may only be handled after

transfer of the prestressing force. For products that are prestressed by a combination of

pretensioning and post-tensioning do not handle before sufficient prestress has been applied to

sustain all forces and bending moments due to handling. Exercise care in handling to prevent

damage to products. Lift and move products so as to minimize stresses due to sudden changes in

momentum.

Calculate pick up and dunnage points. Pick up products only at points designated

as pickup points as shown on the Plans or shop drawings. Maintain all beams in an upright

position at all times.

Evaluate the temporary stresses and stability of beams during their handling. The

temporary stresses induced into the products during handling must be within the acceptable

stresses at release listed in the Department’s Structures Design Guidelines. Take appropriate

action to increase the stability of products during handling when the factor of safety against

lateral buckling instability is below 2.0. Include the expected fabrication tolerance for sweep in

the analysis. The analysis procedure provided by the PCI or similar procedures may be used for

the stability evaluation.

Verify lifting devices for capacity in lifting and handling products, taking into

account various positions during handling. Keep multiple component lifting devices matched to

avoid non-compatible use. When a product has multiple lifting devices, use lifting equipment

capable of distributing the load at each device uniformly to maintain the stability of the product.

When the lifting devices are grouped in multiples at one location, align them for equal lifting.

Take appropriate steps to prevent the occurrence of cracking. When cracking

occurs during handling and transportation, revise handling and transporting equipment and

procedures as necessary to prevent cracking for subsequent products.

450-14.2Storage: Store precast prestressed beams, Double T-Beams, slab beams and

slab units on only two points of support located within 18 inches of the end of the product or as

calculated. Support skewed beams, Double T-Beams, slab beams or slab units within 18 inches

of the end of the full product section or as calculated. Do not support slab beams on the outer

6 inches of the product width. Support other products on an adequate number of supports so as to

keep stresses in the products within the allowable stresses at release listed in the Department's

Structures Design Guidelines. Locate multiple supports (more than two) within 1/2 inch of a

horizontal plane through the top surface of the supports. Adequately brace beams as necessary to

maintain stability. 518FY 2023-24Return to Table of Contents

All supports must be level and on adequate foundation material that will prevent

shifting or differential settlement which may cause twisting or rotation of products. Immediately

pick up products in storage that have rotated or twisted and adjust the supports to provide level

and uniform support for the product.

Support prestressed products that are stacked by dunnage placed across the full

width of each bearing point and aligned vertically over lower supports. Move dunnage points in

accordance with 450-2.3 with the approval of the QC Manager. Do not use stored products as a

storage area for either shorter or longer products or heavy equipment.

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 precast pretensioned products.

Continuous application of water during the initial 72 hour moist curing period

may be interrupted for a maximum of one hour to allow relocation of precast prestressed

concrete elements within the manufacturing facility. Keep the moist burlap in place during

relocation of the element.

450-14.3Shipping: Do not ship precast prestressed concrete products to the project site

prior to the completion of the 72 hour curing period and attainment of the required 28-day

strength. Verification of the shipping strength test, before 28 days, is permitted by testing

compressive strength cylinders that are cured under the conditions similar to the product or by

testing temperature match cured cylinders.

The use of maturity method, ASTM C1074, pulse velocity method in accordance

with ASTM C597, or any other nondestructive test method acceptable to Engineer, is permitted

to estimate the strength before its verification by test cylinders. The shipping strength test is the

average compressive strength of two test cylinders. Do not ship products until accepted and

stamped by the QC Manager or the inspectors under the direct observation of the QC Manager or

designee.

In the case of elements repaired due to major defects, notify the Engineer at least

72 hours in advance of shipping to verify compliance with the Specification.

At the beginning of each project, provide a notarized statement to the Engineer

from a responsible company representative certifying that the plant will manufacture the

products in accordance with the requirements set forth in the Contract Documents and Producer

QC Plan.

The QC Manager’s stamp on each product indicates certification that the product

was fabricated in conformance with the Producer QC Plan, the Contract, and the Specifications.

Ensure that each shipment of prestressed concrete products to the project site is accompanied

with a signed or stamped delivery ticket providing the description and the list of the products.

Evaluate the temporary stresses and stability of all products during shipping and

locate supports, generally within 18 inches from the beam end, in such a manner as to maintain

stresses within acceptable levels. Include impact loadings in the evaluation. Do not support slab

beams on the outer 6 inches of the product width.

450-14.4Erection: Erect precast prestressed products without damage. Meet the

handling and storage requirements of 450-14.1 and 450-14.2 for field operations. Before casting

diaphragms and the deck slab, do not allow the horizontal alignment of prestressed concrete

beams to deviate from a straight line connecting similar points of beam ends by more than the

sweep tolerances specified in 450-2.3. Adequately brace beams as necessary to maintain

stability. 519FY 2023-24Return to Table of Contents

450-15Measurement and Payment

450-15.1General: The work specified in this Section will be measured and paid for as

shown below for the particular item involved. Precast prestressed concrete members are

acceptable to the Department for full payment when all requirements of the Contract Documents

have been met. No partial payments will be made for precast prestressed concrete members until

the 28-day strength requirement, along with other applicable Specification requirements, have

been met.

450-15.2Prestressed Concrete Piling: Payment will be made at the Contract unit price

per foot for the particular type of piling, measured and paid for as specified in Section 455,

including the provisions for cutoffs and splices.

450-15.3Prestressed Concrete Beams: Payment will be made at the Contract unit price

per foot for Prestressed Beams, complete in place and accepted. Final pay lengths will be plan

quantity based on casting lengths, as detailed in the Plans, subject to the provisions of 9-3.2.

450-15.4Prestressed Concrete Slab Units and Slab Beams: Payment will be made at

the Contract unit price per foot for the units, complete in place and accepted. Final pay lengths

will be plan quantity based on casting lengths, as detailed in the Plans, subject to the provisions

of 9-3.2.

450-16Basis of Payment

Price and payment will be full compensation for all work and materials specified in this

Section, including reinforcement, pretensioning strand, embedded ducts, hardware, inserts and

other materials as required, to fabricate, transport and place the product into its permanent

position in the structure.

Payment for the items will be made under the following:

Item No. 450- 1- Prestressed Beams - per foot.

Item No. 450- 2- Prestressed Beams: Florida I-Beams - per foot.

Item No. 450- 3- Prestressed Slab Units - per foot.

Item No. 450- 4- Prestressed Beam U-Beams - per foot.

Item No. 450- 8 Prestressed Beams: Florida Slab Beam – per foot.

Item No. 450- 88- Prestressed Slab Units Transversely Post-Tensioned - per

square foot. 520FY 2023-24Return to Table of Contents PRESTRESSED SOIL ANCHORS

451-1Description

Construct prestressed soil anchors consisting of a high strength steel tendon anchored to the retaining wall on one end and to the soil on the other end through a bulb of pressure injected portland cement concrete grout. Test each anchor by prestressing to the load indicated in the Contract Documents before locking off to the retaining wall. Select the prestressed soil anchor type and the installation method, and determine the bond length a nd anchor diameter. Assume responsibility for installing prestressed soil anchors that develop the load -carrying capacity indicated in the Plans in accordance with 451 -7. Provide corrosion protection for permanent prestressed soil anchors. The Engineer will not require corrosion protection for temporary prestressed soil anchors. Protect anchor tendons from corrosion as shown in the Plans in accordance with 451 -8.

451-2Definitions

structure.

and transmits the tensile force to the soil or rock. For a compression prestressed soil anchor, the bond length will be different from the tendon bond length.

prestressed soil anchor during its service life after completing stressing and testing. The factored design load includes appropriate load factors to ensure that the overall structure has adequate strength for its intended use.

sieve size.

prestressing steel with sheathing and coating when required.

partial-length of prestressing tendon to another.

bond between the prestressing steel and the surr ounding grout or to provide corrosion protection.

anchorage at the bond l ength of the tendon.

purposes.

immediately after the force has been transferred from the jack to the stressing anchorage.

keep the testing equipment positioned.

recording the movement of the tendon at each increment. 521 FY 2023-24 Return to Table of Contents