669 Cylinders shall be in the moisture condition resulting from the selected curing treatment prior to testing. To meet these conditions, the cylinders shall be removed 230 from the molds at the time the structural member is removed from the form work. Cylinders shall be tested in accordance with ASTM C39. The Contractor shall have on file a certificate of calibration for the te sting machine. All cylinders in a cylinder set, for a given age, shall be broken within the time tolerances shown in ASTM C39. The Department will remove cylinder identification tags prior to the Contractor testing the cylinders.
b.Precast Concrete Structural Members When fabricating precast concrete struct ural members which are not prestressed, the number of cylinder sets shall be cast in accordance with the Frequency Manual. 240 The 28-day compressive strength of the concrete for each structural member will be determined by the average strength of the cylinder set representing that member. The fabricator may elect to make additional cylinder sets for use in acceptance testing prior to 28 days. c. Precast Prestressed Concrete Structural Members Cylinder sets shall be cast in accordance with the Frequency Manual. One cylinder set shall be tested and used to determine when the precast prestressed concrete structural member has met or exceeded th e required strength for detensioning the prestressing bed. If an additional cylinder set as described above has been made, the 250 Contractor may test this set to determine if the required strength for detensioning of the prestressing bed has been met or exceeded , or if the required 28-day compressive strength has been met or exceeded prior to an age of 28 days. The Engineer will accept the results from the compression testing on the additional cylinder set, in place of either the detensioning strength test results, or the 28-day compressive strength test results, if the results equal or exceed the respective compressive strength requirements. If an additional cylinder set was not made, or if the additional cylinder set does not meet or exceed the 28-day compressive strength requir ement, the remaining cylinder set shall be tested at 28 days of age to determine the acceptability of the structural members. Coring of precast prestressed concrete st ructural members shall not be performed. Precast prestressed concrete structural me mbers that have been cored will not be accepted. Compressive strength results for cylinders that exceed 28 days in age or results from cylinders that do not have the Department-marked cylinder identification tag intact will result in the structural members not being accepted.
d.Other Requirements Precast concrete structural members which are not prestressed shall have a minimum compressive strength of 4,500 psi in 28 days. 270 Precast prestressed concrete structural members shall be in accordance with the following unless otherwise shown on the plans:
1.Maximum water/cementitious ratio in pounds of water per pound of cementitious material shall be 0.420. 707.04
2.Minimum 28-day compressive strength of concrete shall be 5,000 psi.
3.Minimum compressive strength of concrete at time of 280 prestressing shall be 4,000 psi.
4.Initial tension of prestressing strands shall be as shown on the plans. Inspection of the precast prestressed concrete structural members during manufacturing and checking and testing aggregates, cement, concrete, and steel specimens shall be performed. All specimens shall be furnished without cost to the Department. Inspection, checking, and testing performed by the Department will not relieve the Contractor or the fabricator from performing their own QC inspection, 290 testing, and checking as necessary to main tain QC over the manufacturing, handling, and curing procedure. A permanent record of the force applied to and measured elongation obtained for each prestressing strand shall be provided. The record shall also identify the strand and structural member to which the record app lies. The accuracy of this record shall be certified by the fabricator’s production supe rvisor that it accurate ly represents the force applied and measured elongation. The certified record shall be provided to the Engineer prior to shipment. 300
707.05 Forms
Structural members shall be manufacture d in steel forms which are unyielding, smooth, mortar-tight, and of sufficient rigidity to prevent distortion due to pressure of the concrete. They shall be designed so the finished concrete is in accordance with the required dimensi ons and contours. The design of the forms shall account for the effect of vibration of the concrete as it is pl aced. Forms shall be ch amfered in accordance with 702.13(a). Exposed edges of curbs shall be beveled or edged. Forms shall be set and maintained true to the lines designated until the concrete is sufficiently hardened or for periods hereinafter specified. Interiors of forms shall be treated with an approved form coating which allows them to be released without adhering, discoloring, or 310 otherwise damaging the concrete. Form coa ting materials shall not come in contact with either reinforcing bars or prestressing strands.
707.06 Placing and Finishing Concrete The temperature of the prestressing strands and forms shall be monitored between the time of the application of prestressing force and the placemen t of the concrete.
During hot weather, approved means shall be undertaken to cool the forms immediately prior to placement of the concrete. Where prestressing strands are anchored to abutments that are independent from 320 the form, thermal adjustments shall be made if the temperature of the prestressing 707.05 671 strands at the time of tensioning differs by more than 25°F from the temperature of the concrete mixture during placement. This requirement will not apply to self-stressing beds. Void boxes, inserts, and attachments sha ll be securely fastened to maintain the proper position during concrete placement and consolidation. All voids shall have weep holes or otherwise be vented during beam production until after the initial concrete set, then sealed be fore the beams are shipped. During and immediately after depositing, concrete shall be consolidated with vibrators and suitable spading tools. Vibration shall be applied at the point of deposit and in the area of freshly deposited concrete. The vibrators used may be internal, external, or a combination of both. Internal vibration shall be of sufficient duration and intensity to consolidate thoroughly, but shall not be continued so as to cause segregation. Vibration shall not be continue d at any one point so that localized areas of grout are formed. The entire operation of depositing and consolidating the concrete shall be conducted so the concrete will be smooth, dense, and free from any honeycomb or 340 pockets of segregated aggregates. The concre te in each structural member shall be placed in one continuous operat ion. The outside vertical fa ces of fascia structural members and the exposed face and top of the curb section, if applicable, shall be finished in accordance with 702.21. The tops of all beams and the outside f aces and bottom flanges of the fascia beams shall be sealed in accordance with 709. The sealing requirement will be waived if the concrete meets the low permeability criteria specified in 707.04(c)1. 707.07 Removal of Forms and Curing 350 Curing shall be in an enclosure designed to minimize heat and moisture loss. Insulated blankets may be used. The concrete in the form shall be maintained at a minimum temperature of 50°F during the entire curing cycle. Curing for precast concrete or precast prestressed concrete structural members shall be done by wet curing without supplemental heat or by accelerated curing. During the period of initial set of the structural member and during the accelerated curing by radiant heat, the concrete shall be kept wet by the met hod outlined below for wet curing without supplemental heat. Prior approval shall be obtained for curing methods other than those outlined 360 below. Side forms may be removed when no distortion, slump, or misalignment of the concrete will result. Precast concrete stru ctural members which are not prestressed shall remain on the bottom supporting forms for the span until the concrete has reached a strength of at least 2,000 psi as evidenced by cylinders sets made and cured in the same manner as the slab. 707.07
a.Wet Curing without Supplemental Heat When wet curing without supplemental h eat is used, the exposed surfaces of the 370 structural members shall be covered by two layers of wet burlap and the burlap shall be kept wet to ensure that free water is always present. In lieu of using wet burlap, the Contractor may propose an alternate method which provides a moist environment with free water being present at all times. Written approval from the Engineer will be required prior to use of the proposed alte rnate method. Additional curing of precast concrete or precast prestressed concrete structural members will not be required provided the minimum specified ultimate strength can be obtained. In precast prestressed concrete stru ctural members, wet curing without supplemental heat shall continue until the compressive strength of the concrete reaches 380 or exceeds the strength specified for transfer of prestress or detensioning. At this point wet curing is considered to have concluded. Detensioning shall be performed within 6 h after wet curing has concluded. In precast concrete structural members which are not prestressed, wet curing without supplemental heat shall continue until such time as the compressive strength of the concrete reaches the strength specified for stripping of forms.
b.Accelerated Curing When accelerated curing of the concrete is used, it shall be done by low pressure 390 steam or radiant heat curing. Radiant heat may be applied by means of pipes circulating steam, hot oil, hot water, or by electric heating elements. When steam is used, the jets shall be positioned so that they do not discharge directly on the concrete, forms, or cylinders. The steam shall be at 100% relative humidity to prevent loss of moisture and to provide moisture for proper hydration of the cement. Except to maintain a minimum concrete temperature of 50°F, heat shall not be applied until the concrete has attained initial set. The time of initial set may be determined by ASTM C403. Once the penetration resistance, as performed in accordance with ASTM C403, equals or ex ceeds 500 psi, accelerated curing may 400 begin. When the initial set is not determined by ASTM C403, the initial application of heat shall be a minimum of 4 h after final concrete placement. When retarders are used and the initial set is not determined by ASTM C403, this time shall be increased to a minimum of 6 h after final co ncrete placement. Heat shall always be applied at a controlled rate following the initial set of the concrete, and an effective method of retaining the heat and moisture in the concrete shall be used during the entire curing cycle. During the initial application of radiant heat or live steam, the temperature measured in the concrete shall increase at an average rate no t exceeding 36°F/h. The 410 maximum concrete temperature shall not exceed 158°F. A minimum of three time and temperature recording devices, capable of recording temperatures in degrees Fahrenheit at intervals not exceeding 15 minutes, shall be provided throughout a 707.07 673 contiguous form group and common heat source. The time and temperature recording devices shall be located at the portions of the contiguous form group likely to experience the maximum temperatures during curing. The curing temperature shall be sustained until the concrete has reached the minimum required compressive strength for detensioning the structural members. Once the concrete has achieved the required compressive strength, detensioning shall 420 be performed while the concrete is still warm and moist. Detensioning operations shall not interfere with the curing of the structural member. As the application of heat is discontinue d, the concrete temperature shall decrease at a rate not to exceed 50°F/h. When the concrete temperature has reached 40°F or less above the ambient temperature outside the curing enclosure, accelerated curing is considered to have concluded. A thermometer shall be provided to monitor ambient air temperatures. This thermometer does not have to have recording capabilities. The time and temperature recording devices shall be used to verify compliance 430 with the heating and cooling rates contained herein. When multiple structural members are cast in the same bed, all members shall meet or exceed the specified release strength prior to detensioning. Additional curing of precast concrete or precast prestressed concrete structural members will not be required provided the mini mum specified ultimate st rength can be obtained. A grinder or other methods that induce minimal amounts of heat into the prestressing strand shall be used to cut off prestressing strands. The ends of the concrete structural member where prestressing strands have been cut to be flush with 440 the end of the member shall be coated with bituminous mastic sealant in accordance with 907.11. All prestressing strands that are exposed and protrude from the end of the beam shall be protected from rusting by use of a spray, brush, or roller-applied rust-inhibiting paint or other material that is not considered detrimental to bonding with concrete.
707.08 Handling and Shipping Precast concrete and precast prestressed concrete structural members shall not be
subjected to excessive abuse which produces crushing or undue marring of the concrete. All structural members damaged du ring handling, storing, transporting, or 450 erecting shall be replaced. Unless otherwise approved, precast concrete and precast prestressed concrete structural members shall be handled with a suitable hoisting device provided with a spreader sling. The spreader shall be of sufficient length to prevent horizontal forces being produced in the structural member due to lifting and shall be equipped with leads and hooks at each end. Unless otherwise shown on the contract plans, the location of the lifting points along the tops of the beams shall be in accordance with the transportation support point requirements given herein. If any other method of handling is used, it shall be shown on the working drawings. If the method produces horizontal forces in th e precast concrete or precast prestressed 707.08 674 concrete structural member, design calculations shall be submitted showing resulting 460 stresses. The design of the structural members shall be satisfactory to handle these stresses in accordance w ith AASHTO LRFD Bridge Design Specifications. The structural members shall be lifted by the devices and procedures shown on the working drawings. The structural members shall remain in an upright position at all times and shall be supported as indicated herein when in storage and during transportation to the construction site. In storage, all structural members shall be fully supported across their width on 470 battens not less than 4 in. wide with one being placed at each end at the centerline of the bearing. The supports of the struct ural members while in storage shall be maintained in a level position so no twisting occurs. Precast concrete structural members shall not be lifted, shipped, or used until the concrete compressive strength reaches a mi nimum of 4,500 psi for members which are not prestressed and 5,000 psi for members which are prestressed. During transportation, the structural members shall be supported with truck bolsters or battens no less than 4 in. wide which are padded with no less than 1/2 in. 480 of rubber. The ends of I-beams, U-beams, and bulb-T beams shall extend no more than the depth of the beam and not more than 3 ft 6 in. beyond the supports. The ends of box-beams shall extend no more than 1 1/2 times their depth and not more than 3 ft beyond the supports. The ends of slabs shall extend no more than the depth of the beam beyond the supports. Supports of cantilever beams shall be as shown on the plans. Trucks with double bolsters will be allowed, provided the beams are fully seated on the outer bolsters and the inner bolsters are no more than 8 ft from the ends of the beams. Wood blocks or other suitable material shall be placed under the tie chains to prevent chipping the 490 concrete.
707.09 Placing Structural Members If the method of lifting the structural members in the field differs from the method shown on the beam fabrication working drawings, the Contractor shall submit working drawings and calculations in accordance wi th 707.08. Erection of precast prestressed
concrete structural members shall commence at the centerline and proceed out to the curb, one member at a time. As each struct ural member is placed, the transverse tie bars, if shown on the plans, shall be inserted and secured. Any shifting of the structural members shall be done while they are held free of the supports by the hoisting device. 500 The use of a steel pinch bar will not be allowed. Structural members shall be set to proper line and grade with uniform bearing on bridge seats, mortar joints, or bearing pads as required on the plans. 707.09 675 When required, structural members shall be secured to the pier or bent with dowel rods. Holes for dowels shall be filled with mortar at fixed ends and with crack or joint filler at expansion ends. Longitudinal keyway joints shall be cleaned. A coat of cement mortar shall be scrubbed on the surface. The joint shall be filled with a non-shrinking grout composed of 1 part portland cement, 2 parts No. 23 fine aggregate, and an approved non-shrinking additive or a non-shrink, non-metallic cementation grout in 510 accordance with ASTM C1107. All bolts or dr ains shown on the plans as necessary or desirable to be placed in the concrete sh all be placed by the methods and at the locations shown on the plans. Necessary tie rods, tie bolts, and hardware for tying structural members together shall be furnished. Dowel holes shall not be grouted nor concrete or the forming thereof, be placed in floor slabs, diaphragms, or shear keys prior to receipt of complete documentation of the acceptability of the structural members and bearing pads, including the satisfactory laboratory reports and certifica tions in accordance with 915.04(f). Neither the structural members, nor the bearings will be considered incorporated into the work, 520 and neither will be paid for until this documentation is accomplished satisfactorily. Railing, when required, shall be of the type shown on the plans. The component parts shall be in accordance with 706, unless otherwise indicated on the plans. Other precast concrete or precast prestressed concrete structural members shall be placed in the structure in accordance wi th the plans and the specifications or special provisions indicated for the type of structure being built. Cranes or other heavy erection equipment may be operated on the precast concrete or precast prestressed concrete structural members only if approved in writing and if 530 a proposed operating procedure is submitted showing loading, dist ribution of loads, resulting stresses, and that the design of the structural members is satisfactory to handle these loads. However, such approval shall not relieve the Contractor of any damage from this operation.
707.10 Blank
707.11 Method of Measurement
Precast concrete or precast prestressed concrete structural members will be measured by the linear foot. Railing will be measured in accordance with 706.07 if 540 specified as a pay item. Structural steel for intermediate diaphragms will not be measured.
707.12 Basis of Payment
The accepted quantities of precast concrete or precast prestressed concrete structural members will be paid for at the contract unit price per linear foot for structural member, concrete, of the type and size specified. Railing will be paid for in accordance with 706.08 when specified as a pay item. 550 707.12 676 Payment will be made under: Pay Item Pay Unit Symbol Structural Member, C oncrete, ____, ____ ................................. LFT type size Reinforcing bars, WWR, prestressing strands, elastomeric bearing pads, modifications to bearing pads, bearing beams required for box beams, bearing assemblies required for I-beams, bulb-T beams, U-beams, box beams, bearing plates, 560 threaded reinforcing bars, threaded inserts in fascia beams, hex bolts, sealer on the outside face and bottom flange of fascia beams and on the tops of all beams, working drawings and design calcula tions, and necessary incidental s shall be included in the cost of the pay items of this section. The cost of tensioning rods and steel plates shall be included in the cost of the pay items of this section. The cost for providing all molds, cylinder identification tags, facilities, labor, testing, testing apparatuses, required trial ba tches, materials, and all other incidentals 570 necessary to prepare and cure the test speci mens and ensure that the concrete meets the requirements of this specification shall be included in the cost of the pay items in this section. No payment will be made for removing and replacing prestressing strands due to excessive wire breakage, or replacing precast concrete or precast prestressed concrete structural members damaged during handling, storing, transporting, or erecting. The cost of railing shall be included in the cost of the pay items of this section if such railing is not specified as a pay item. 580 The cost of all materials, including galvanizing, labor, and equipment for furnishing and installing steel intermediate diaphragms shall be included in the cost of structural member, concrete of the type and size specified. The cost of time and temperature recording devices and their monitoring shall be included in the cost of the structural members. The cost of a field office or of providing the field office items listed herein shall be included in the cost of the pay items of this section. 590 707.12
Source: Indiana Standard Specifications, 2024 Edition. Pages 2–11 of 1,248.