00550.00 500 Section 00550 - Precast Prestressed Concrete Members Description
00550.00 Scope - This Work consists of the manufacture, storage, transportation and installation of
precast prestressed concrete girders, box girders, slabs or other concrete members. Precast prestressed concrete members in this Specification will be referred to as members. 00550 .02 Design - Essential elements of design and section dimensions for members are as shown. Submit unstamped Working Drawings , stressing calculations, and detensioning sequence for all members for approval according to 00150.35.
00550.03 Alternate Designs - Agency design specifications will be furnished by the Agency upon
request. The Contractor may propose another type of prestressing system or different member dimensions provided the following requirements are met: • Before manufacturing the members, submit stamped design calculations, Working Drawings , and specifications for all modified members according to 00150.35. • With the calculations, show that the member meets all applicable ser vice and strength limit states used for the Agency design. • Do not increase member dimensions by more than 1 inch, except that bulb width and overall depth may be increased up to 2 inches from the dimensions shown. Where overall depth is increased, verify that the required minimum vertical roadway clearance has been maintained. • Do not incorporate alternate Materials or members into the Work until the proposal has been accepted by the Engineer. • Make any structural changes required to accommodate an approved alternate prestressing system or section at no additional cost to the Agency.
00550.04 Member Tolerances:
a.General - Fabricate members to the dimensional tolerances in the PCI Manual for Quali ty Control for Plants and Production of Precast and Prestressed Concrete Products and as specified below. Acceptance or rejection of members outside these tolerances will depend on how the Structure 's strength, rideability and appearance are affected.
b.Twist - Provide members with a relative twist of member bearing surfaces between member ends of less than or equal to 1/16 inch per foot of bearing width measured at right angles to the centerline of the member.
00550.05 Fabricator Certification and Q ualification - Certification under the PCI Plant Certification
Program is required for all plants producing precast prestressed concrete bridge members. Certification in Bridge Group B3 or Bridge Group B4 is mandatory for the fabrication of prestressed straight strand bridge members. Certification in Bridge Group B4 is mandatory for the fabrication of prestressed draped strand bridge members. Materials
00550.11 Materials - Furnish Material s meeting the following requirements:
00550.20 Backer Rod ........................................................................................... 02440.14 Concrete Coating ....................................................................................... 02210 Concrete ..................................................................................................... 02001 Deformed Bar Reinforcement ................................................................ 02510.10 Epoxy and Non-Epoxy Grouts .................................................................... 02080 Epoxy Coating ....................................................................................... 02510.11 Keyway Grout ........................................................................................ 02080.30 Portland Cement Concrete Repair Material ................................................ 02015 Hot Applied Joint Sealant ...................................................................... 02440.30 Prestressing Reinforcement ....................................................................... 02515 Tie Rods ................................................................................................ 02560.30
00550.12 Acceptance of Concrete - Acceptance of concrete will be according to Section 00165 and
the following:
a.Aggregate - Acceptance of Aggregate will be based on the Contractor's quality control testing, if verified, according to Section 00165.
b.Plastic Concrete - Acceptance of plastic concrete will be based on tests performed by the QCT, according to Section 02001.
c.Hardened Concrete:
1.General - Acceptance of hardened concrete will be based on analysis of compressive strength test results of cylinders cast and cured by the Contractor and tested according to AASHTO T 22 by a CSTT at an ODOT certified laboratory and verified according to Section 00165.
2.Sampling and Testing - Obtain a sample from a delivery vehicle, selected at random, during placement in each bed. Test the sample for temperature, slump, density and air content and cast at least three cylinders for testing at 28 D ays. Cure the cylinders in a manner similar to the members they represent. Alternately, the cylinders may be cured in a curing chamber correlated in temperature with the concrete in the beds. Leave the cylinders in the bed with the member or in the curing chamber until the member is stripped. After the member is stripped, place the acceptance cylinders in storage in a moist condition according to AASHTO T 23.
3.Acceptance - Hardened concrete members with an ASTV meeting or exceeding the specified desi gn strength, ƒ' c, will be acceptable for strength. If the ASTV is less than ƒ'c but at least 85 percent of ƒ'c, the Engineer may review the results to determine if the member is suitable for the intended purpose. If suitable, the concrete represented by an ASTV less than ƒ' c may be accepted subject to a price adjustment according to 00150.25. Concrete that has an ASTV less than 85 percent of ƒ' c will not be accepted. All costs of removal, replacement, and all related Work are the Contractor's responsibi lity. Equipment
00550.20 Prestressing Equipment - Provide hydraulic jacks equipped with calibrated pressure
gauges. Calibrate the jack and gauge combination and furnish a graph or table showing the calibration to the Engineer. 00550.25 502 If other types of jacks are used, furnish calibrated proving rings or other devices that accurately indicate the jacking forces. Recalibrate the jack and gauge combination annually or at any time the results are in question.
00550.25 Vibrators - Provide either internal or ex ternal vibrators in working condition meeting the
manufacturer's rating. When epoxy coated reinforcement is used, use internal vibrators fitted with a manufactured rubber head to minimize damage to the epoxy coating. Construction
00550.40 Forming - Provide forms that are mortar -tight and sufficiently rigid to conform to the
specified dimensions without appreciable distortion, warping or opening of joints. Before placing concrete in the forms, remove all dirt, sawdust, excess wat er and other foreign material. Tighten forms before depositing new concrete on or against hardened concrete.
00550.41 Placing Reinforcement - Place reinforcement according to the Plans , Section 00530, and
the Specifications.
00550.42 Pretensioning :
• Do not proceed with stressing prior to receiving the Engineer's approval of stressing calculations submitted according to 00550.02. • Provide a person, skilled i n the use of the system of prestressing to be used, to supervise the Work and assist the Engineer. • Hold the prestressing strands accurately in position and stress by jacks meeting the requirements of 00550.20. • Determine the force induced in the strands by measurement of elongation and, independently, by direct measurement of force using a pressure gauge dynamometer and load cell. If the difference in force determination for the two methods exceeds 5 percent, determine the cause and correct it. • Measure stra nd elongation on the first and last strands stressed, and on at least 10 percent of the other strands in the bed. • Record the jacking forces and the elongations produced. • In single straight strand tensioning, and in a completely open bed with no headers or other possible sources of friction, loads indicated by the gauging system may be used.
00550.43 Placing Concrete :
a.General - Place concrete so that the finished members are uniform and monolithic, free from cold joints. Do not deposit c oncrete in the forms until the Engineer has inspected and approved the placement of reinforcement, conduit, anchorages and prestressing steel. In preparation for placing concrete, prepare forms according to 00550.40. Remove struts, stays and braces servi ng temporarily to hold the forms in correct shape and alignment before the placing of concrete when the concrete placing has reached an elevation rendering them unnecessary. Remove these temporary members entirely from the forms and do not bury them in the concrete. 00550.45 Place concrete close to its final position, without segregation of M aterials or displacement of the reinforcement.
b.Consolidation - Consolidate concrete, during and immediately after placing, by mechanical vibration as follows: • Operate v ibrators at frequencies that produce consolidated placements. • Do not use vibration for shifting concrete to the extent of causing segregation. • Vibrate at points uniformly spaced and not further than twice the radius over which vibration is visibly effectiv e. • Continue vibration until the concrete is thoroughly consolidated, but not until segregation occurs or localized areas of grout form.
00550.44 Hot or Cold Weather - Produce and p lace concrete within the temperature range specified
in 02001.20(d). When the air temperature is, or is expected to be, below 40 °F or above 100 °F, observe the following precautions: • Do not place concrete on forms, reinforcing steel or appurtenances when the temperature of these facilities is below 40 °F. Provide heat to maintain their temperature at 40 °F minimum. • Do not place concrete when the form temperature is 100 ° F or more.
00550.45 Curing - Cure members with low -pressure steam or radiant heat inside a suitable
enclosure to contain the steam or heat, and minimize moisture and heat loss.
a.Curing Temperature - Measure cure temperature by one of the two following methods:
1.Measuring Enclosure Temperature: • Equip the enclosure with 24- hour recording thermometers at each end of each casting bed. Record the temperature for each thermometer on a single chart for each 24- hour period. • Do not allow the curing temperature within the enclosure to exceed 160 °F. During the initial application of live steam or radiant heat, do not allow the temperature within the enclosure to increase at a rate exceeding 40 °F per hour.
2.Measuring Concrete Tem perature: • Embed a thermocouple 6 inches to 8 inches from the top or bottom of the member on its centerline and near its midpoint. • Record the concrete temperature with a calibrated recorder that provides a continuous record of time and temperature througho ut the curing cycle. • Do not allow the concrete temperature to exceed 190 °F. During the initial application of steam or radiant heat, do not allow the concrete temperature to increase at a rate exceeding 80 °F per hour.
b.Curing with Low -Pressure Steam: • Make the initial application of steam after initial set of concrete as determined by AASHTO T 197 ( ASTM C403). • Provide a steam supply line to the enclosure equipped with a motor -operated modulating steam control valve operated by a temperature- sensing element located in the enclosure. 00550.46 504 • Provide steam at 100 percent relative humidity. • Do not apply steam directly on the concrete, form surfaces or test cylinders. • Distribute the steam within the enclosure through suitable ports located on each side of the units within the enclosure at not more than 30 foot centers to keep the units being cured completely and uniformly surrounded with steam.
c.Curing with Radiant Heat - Radiant heat may be applied to beds by means of pipes circulating steam, hot oil or hot water, by electric blankets or heating elements adjacent to forms, or by circulating warm air under and around forms. Do not allow pipes, blankets or heating elements to be in contact with concrete, form surfaces, or test cylinders.
00550.46 Release of Prestress - Transfer bond stress to the concrete, or release end anchors, only
when the concrete has attained the minimum compressive strength shown or specified for such transfer of load. Cut or release the elements according to the sequence shown on the reviewed Working Drawings so lateral eccentricity of prestress will be a minimum. Determine the compressive strength of the concrete to establish time for detensioning by testing standard cylinders cast and cured identically with the member. Cast and test cylinders used to determine release time according to AASHTO T 22 and AASHTO T 23.
00550.47 Surface Finish - Apply the specified finish to each surface as shown or specified.
Where no finish is shown or specified, provide a Class 1 surface finish to all exposed concrete surfaces, except on the tops of members, unless shown otherwise. For concrete surfaces that are not exposed, provide a general surface finish except on the tops of members. For surfaces receiving a Class 1 surface finish (ground and coated), finish the surfaces when the member is in its final position and finish to a point 1 foot below the finished ground line. After the concrete has been floated to produce a uniform surface and hardened sufficiently, provide a uniform textured finish on the top of members using a tool with 1/8 inch wide tines spaced 3/4 inch apart that will mark the finished surface to a depth of 1/8 inch to 3/16 inch. Do not overlap the texturing. Produce the texture transverse to the roadway centerline and full member width. In addition for members with an overlay less than 3 inches thick, struck the concrete to grade and Cross Section and provide a uniform surface according to 00540.55. For the top of members used as a roadway surface, strike the concrete to grade and Cross Section and float it to produce a uniform smooth surface according to 00540.55. After the members are erected in the final position, provide deck roadway finish as shown. If not shown, provide deck roadway texturing according to 00540.50(c).
a.General Surface Finish - Apply a general surface finish as a final finish or preparatory to a higher class finish. Remove strands in members, except members with ends to be embedded in concrete, to a depth of 1 inch from the face of the concrete and point up the resulting holes flush with the end of the member with an epoxy grout from the QPL. Remove all metal form bolts, snap ties and any other metal to a depth of 1 inch below the finished concrete surface. Repair air pockets over 1/2 inch in depth, all form tie removals, Rock pockets and unsound concrete, and fill resulting holes or depressions with concrete or PCC repair Material. On exposed surfaces, correct all bulges, fins, depressions, repairs, stains or discolorations to produce a smooth surface with uniform texture, lines, and appearance. The Engineer will determine the extent of required repairs. 00550.49
b.Class 1 Surface Finish (Ground and Coated) - After completion of the general surface finish: • Grind the surface with a power grinder or other equal method to remove all laitance and surface film. • Thoroughly saturate the surface with water and coat while damp with a coating material conforming to 02210.30. • Apply a minimum of two coats of coating material. The second coat may be applied at any time after the previous coat does not adhere to the finger. Apply additional coats as required to provide uniformity in coverage and color. • Mortar sand may be added to the coating material to achieve a uniform surface.
00550.48 Exposed Reinforcement - After a member is removed from the casting bed, clean any
projecting reinforcement of dirt, oil, grease, rust and corrosives and protect it from damage until concrete is cast around it.
00550.49 Lifting, Storing, Transporting, Erecting, and Bracing - Be responsible for the safety of
precast members during all stages of construction. Include lifting and storage details on the Working Drawings for all precast members. Lifting, storage, transporting, erecting, and bracing details will not be reviewed by the Engineer. Lifting, storage, transporting, erecting and bracing of members is the sole responsibility of the Contractor subject to the following requirements:
a.Lifting: • Lift members so as to prevent damage. • Lift members at the support points specified by the manufacturer. • Lift members in a manner that does not cause damaging bending or torsional forces. • Members will be rejected if not handled correctly as specified.
b.Storing - Store members with support points that are level transversely.
c.Transporting - Transport members from the casting yard not less than 7 Calendar Days after casting, not less than 7 Days after all concrete patching and repairing is complete and after 28-Day compressive strengths have been achieved. • Temporary prestress strands may be added to precast concrete members for the purpose of controlling concrete stresses during transportation. Detension these strands after the members are set in the field and prior to establishing grades for the bottom of deck forms. • Temporary strands may be either post-tensioned or pretensioned in the fabrication yard. Debond post-tensioned strands completely from end to end. Debond pretensioned strands completely from end to end except for a length at the end of the beam equal to the development length of the strand, but not more than 10 feet. Pretensioned strands may be used for simple span girders only. • The stress from temporary strands may be transferred to the concrete member only after the stress from the permanent strands has been transferred to the concrete member. This requirement may be waived for pretensioned strands if calculations are submitted, and approved by the Engineer, that show acceptable stress levels in the member. • For pretensioned temporary strands, form a hole in the girder at mid-span or at each end of the debonded length, so the strand can be cut for detensioning. Ensure these holes are free-draining and patched after detensioning. The detensioned strands may be left in place. 00550.50 • Post-tensioned temporary strands may be placed in a conduit or debonded full length with direct contact sheathing. In either case, patch the holes formed by the conduit or sheathing to a depth of 1 1/2 inch, after the removal of the conduit or sheathing to this same depth. The detensioned strands may be left in place. • Submit stamped calculations that predict the effect of temporary strands on initial and long term girder Camber according to 00150.35. Damaged members will be rejected. Replace damaged members, or if allowed by the Engineer, repair damaged members to the Engineer's satisfaction at no additional cost to the Agency.
d.Erecting and Bracing - After a member has been erected and until it is secured to the Structure, provide temporary bracing as necessary to resist wind or other loads. Provide the Engineer with an erection plan and bracing details at least 2 Days prior to erecting girders. Bracing details are not necessary for side-by-side slab and box beam construction.
00550.50 Tie Rods - Furnish tie rods according to the Plans and Section 02560. Install as follows:
• Clean and lubricate tie rods and nuts before installation. • Lubricate galvanized tie rods and nuts with a lubricant from the QPL containing dye that visibly contrasts with the color of galvanizing or coating. • Install compressible washer type direct tension indicators under the turned nuts and tighten the nuts as recommended by the manufacturer until the gaps in the indicators are nil or as shown. A nil gap is defined as a gap when the number of spaces between the protrusions of a direct tension indicator in which the 0.005 inch feeler gauge is refused at each tie rod equals or exceeds 2, 3, 3, 4, or 4, when the number of spaces between protrusions in the direct tension indicator are 4, 5, 6, 7, or 8, respectively, and a visible gap exists in at least one space.
00550.51 Keyway Grouting for Slabs, Box Beams, and Integral Deck Members - After forms
have been removed from slabs, box beams and integral deck bulb tees, sandblast all keyways to remove residual form oil and any other foreign material. After the members are in place and the tie rods are tensioned (for slabs and box beams) or welded connections are made (integral deck bulb tee girders), clean the keyways of all foreign material and keep moist for 24 hours before grouting. For slabs and box beams, after the tie rods are tensioned, seal the space remaining at the bottom of the keyways with a backer rod as shown before grouting. Do not pour keyway grout unless the air temperature is above 45 °F and at or below the maximum air temperature recommended by the manufacturer. Water cure grout for the period of time indicated by the manufacturer.
00550.52 Hot Applied Joint Sealant for Integral Deck Members with AC Wearing Surface - After
grout is poured to the level of the keyway shown for slabs and box beams, remove loose grout, and other foreign material from exposed keyway walls. After keyway grout is fully cured, dry surfaces to be sealed immediately before installing hot applied joint sealant. Install hot applied joint sealant according to the manufacturer's directions. Cure the filler sufficiently to resist the pressures and temperatures of the paving operation before the wearing surface is placed.
00550.53 Differential Camber Correction for Adjacent Precast Prestressed Concrete Members
with No ACP Wearing Surface or with No Cast-in-place Concrete Deck - Correct differential Camber between adjacent slabs, box beams or integral deck bulb tee girders in a span (measured in place at the site) by a method approved by the Engineer if the variance between adjacent members or stages is 1/4 inch or more at the top edge corners at midspan. 00550.90 Equalize the Camber differences by either Patching with an epoxy or non-epoxy grout or other approved method, at no additional cost to the Agency. Before Patching, clean the area by sandblasting. Water cure the patch for the period of time indicated by the manufacturer. If Patching is used, slope it away from the joint on a 1V:6H Slope or flatter. Measurement
00550.80 Measurement - The quantities of Work performed under this Section will be measured on
the length basis, and will be the sum of the horizontal lengths shown for each type and size of member. Field measurement of each member length will not be made. The quantities will be determined by calculating the theoretical horizontal length shown, added together for a total for each type and size. Stirrup extension reinforcement will be measured according to 00530.80. Estimated quantities of reinforcement for the lump sum method will be listed in 00530.80(a) of the Special Provisions. Payment
00550.90 Payment - The accepted quantities of Work performed under this Section will be paid for
at the Contract unit price, per unit of measurement, for the following items: Pay Item Unit of Measurement
a.____ Precast Prestressed Girders ........................................................ Foot
b.____ Precast Prestressed Slabs ........................................................... Foot
c.____ Precast Prestressed Box Beams ................................................. Foot In item (a), the girder type and depth will be inserted in the blank. In item (b), the slab depth will be inserted in the blank. In item (c), the box beam depth will be inserted in the blank. Stirrup extension reinforcement, as shown, will be paid for according to 00530.90. Payment will be payment in full for furnishing and placing all Materials, and for furnishing all Equipment, labor and Incidentals necessary to complete the Work as specified. No separate or additional payment will be made for: • reinforcement, prestressing steel, enclosures for post-tensioning steel, anchorages, plates, nuts, and all other Material contained within the member • furnishing, transporting, and placing members • furnishing and tensioning rods and pretensioning strands • grouting keyways and installing poured joint filler • furnishing and installing metal diaphragms for integral deck bulb tees • furnishing and placing anchor bolts, dowels and diaphragm threaded rods where applicable • furnishing and installing plain elastomeric bearing pads surface finish on members 00555.00
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Source: Oregon Standard Specifications for Construction, 2024 Edition. Pages 566–573 of 1,268. View official source ↗