Div03.pdf

Lower Rio Grande Flood Control Project North Banker Floodway Levee Improvements Project Hidalgo County, Texas

DIVISION 03-

USIBWC Contract No.: IBM09B0002 CONCRETE

US INTERNATIONAL BOUNDARY & WATER COMMISSION

GOVERNING TECHNICAL SPECIFICATIONS AND PROVISIONS

DIVISION 03 – CONCRETE

DIVISION 03-

USIBWC Contract No.: IBM09B0002 CONCRETE

This Page Intentionally Blank

CONCRETE STRUCTURES

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Section 03 04 20

PART 1 GENERAL

1.1 SECTION INCLUDES

Construct concrete structures.

1.2 MEASUREMENT AND PAYMENT

The work performed by the Contractor under this specification shall not be paid for directly, but shall be considered subsidiary to the various bid items under this contract

1.3 REFERENCES

A. TxDOT Departmental Material Specifications

1. DMS-4640 - Chemical Admixtures for Concrete

2. DMS-4650 - Hydraulic Cement Concrete Curing Materials and Evaporation Retardants

3. DMS-6100 - Epoxy and Adhesives

4. DMS-6160 - Waterstops, Nylon Reinforced Neoprene Sheet, and Elastomeric Pads

5. DMS-6310 - Joint Sealants and Fillers

B. TxDOT Test Procedures

1. Tex-424-A - Obtaining and Testing Drilled Cores of Concrete

2. Tex-426-A - Estimating Concrete Strength by the Maturity Method

3. Tex-436-A - Measuring Texture Depth by the Sand Patch Method

4. Tex-440-A - Initial Time of Set of Fresh Concrete

C. U.S. Department of Commerce Voluntary Product Standard PS 1

1.4 SUBMITTALS

A. Conform to Section 01 33 00 - Submittal Procedures.

B. Provide copy of current Texas Department of Transportation (TxDOT) Plant Certification.

C. Submit proposed mix design and test data for each type and strength of concrete in the Work.

D. Submit laboratory reports prepared by an independent testing laboratory stating that materials used comply with requirements of this Section.

E. Submit manufacturer's mill certificates for reinforcing steel. Provide specimens for testing when required by the COR.

F. Submit certification from concrete supplier that materials and equipment used to produce and deliver concrete comply with this Specification.

G. When required on Drawings, submit shop drawings showing reinforcement type, quantity, size, length, location, spacing, bending, splicing, support, fabrication details, and other pertinent information.

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H. For waterstops, submit product information sufficient to indicate compliance with this Section, including manufacturer's descriptive literature and specifications.

PART 2 PRODUCTS

2.1 CONCRETE

Provide concrete conforming to Section 03 04 21, “Hydraulic Cement Concrete.” For each type of structure or unit, provide the class of concrete shown on the plans or in pertinent governing specifications.

2.2 GROUT OR MORTAR

Provide grout or mortar conforming to Section 03 04 21, “Hydraulic Cement Concrete” Paragraph 2.6.

2.3 LATEX

Provide an acrylic-polymer latex admixture (acrylic resin emulsion per DMS-4640, “Chemical Admixtures for Concrete”) suitable for producing polymer-modified concrete or mortar. Do not allow latex to freeze.

2.4 REINFORCING STEEL

Provide reinforcing steel conforming to Section 03 21 10, “Reinforcing Steel.”

2.5 EXPANSION JOINT MATERIAL

Provide materials that conform to the requirements of DMS-6310, “Joint Sealants and Fillers”:

• Provide preformed fiber expansion joint material that conforms to the dimensions shown on the plans. Provide preformed bituminous fiber material unless otherwise specified.

• Provide a Class 4, 5, or 7 low-modulus silicone sealant unless otherwise directed.

• Provide asphalt board that conforms to dimensions shown on the plans.

• Provide re-bonded neoprene filler that conforms to the dimensions shown on the plans.

2.6 WATERSTOP

Provide rubber or polyvinyl chloride (PVC) waterstops that conform to DMS-6160, “Waterstops, Nylon Reinforced Neoprene Sheet, and Elastomeric Pads,” unless otherwise shown on the plans.

2.7 EVAPORATION RETARDANTS

Provide evaporation retardants that conform to the requirements of DMS-4650, “Hydraulic Cement Concrete Curing Materials and Evaporation Retardants.”

2.8 CURING MATERIALS

Provide membrane curing compounds that conform to the requirements of DMS-4650, “Hydraulic Cement Concrete Curing Materials and Evaporation Retardants.”

Provide cotton mats that consist of a filling material of cotton “bat” or “bats” (at least 12 oz. per square yard) completely covered with unsized cloth (at least 6 oz. per square yard) stitched longitudinally with continuous parallel rows of stitching spaced at less than 4 in., or tuft both longitudinally and transversely at intervals less than 3 in. Provide cotton mats that are free from tears and in good general condition. Provide a flap at least 6 in. wide consisting of 2 thicknesses of the covering and extending along 1 side of the mat.

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Provide polyethylene sheeting that is at least 4 mils thick and free from visible defects. Provide only clear or opaque white sheeting when the ambient temperature during curing exceeds 60°F or when applicable to control temperature during mass pours.

Provide burlap-polyethylene mats made from burlap impregnated on 1 side with a film of opaque white pigmented polyethylene, free from visible defects. Provide laminated mats that have at least 1 layer of an impervious material such as polyethylene, vinyl plastic, or other acceptable material (either as a solid sheet or impregnated into another fabric) and are free of visible defects.

2.9 EPOXY

Unless otherwise specified, provide epoxy materials that conform to DMS-6100, “Epoxy and Adhesives.”

PART 3 EXECUTION

3.1 EQUIPMENT

A. Fogging Equipment

Use fogging equipment that can apply water in a fine mist, not a spray. Produce the fog using equipment that pumps water or water and air under high pressure through a suitable atomizing nozzle. Use hand-held mechanical equipment portable enough to use in the direction of any prevailing wind and adaptable for intermittent use to prevent excessive wetting of the concrete.

B. Transporting and Placing Equipment

Use appropriate transporting and placing equipment such as buckets, chutes, buggies, belt conveyors, pumps, or other equipment as necessary. Do not transport or convey concrete through equipment made of aluminum. Use carts with pneumatic tires for carting or wheeling concrete over newly placed slabs.

Use tremies to control the fall of concrete or for underwater placement. Use tremies that are watertight and of large enough diameter to allow the placement of the concrete but less than 14 in. in diameter. For underwater placements, construct the tremie so that the bottom can be sealed and opened once the tremie has been fully charged with concrete.

Use pumps with lines at least 5 in. I.D. where Grade 2 or smaller coarse aggregate is used, and at least 8 in. I.D. for Grade 1 coarse aggregate.

C. Vibrators

Use immersion-type vibrators for consolidation of concrete. Provide at least 1 standby vibrator for emergency use.

D. Screeds and Work Bridges for Bridge Slab

For bridge slabs use a self-propelled transverse screed or a mechanical longitudinal screed. Use transverse screeds that are able to follow the skew of the bridge for skews greater than 15° unless otherwise compliance-confirmed by the COR. Equip transverse screeds with a pan float. Manually operated screeding equipment may be used if compliance-confirmed for top slabs of culverts, small placements, or unusual conditions.

Use screeds that are rigid and heavy enough to hold true to shape and have sufficient adjustments to provide for the required camber or section. Equip the screeds, except those of the roller drum type, with metal cutting edges.

For bridge slabs, use sufficient work bridges for finishing operations. Mount a carpet drag to a work bridge or a moveable support system that can vary the area of carpet in contact with the concrete. Use carpet pieces long enough to cover the entire width of the placement. Splice or overlap the carpet as necessary. Ensure that enough carpet is in

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Use artificial grass-type carpeting having a molded polyethylene pile face with a blade length between 5/8 and 1 in. and with a minimum weight of 70 oz. per square yard.

Ensure that the carpet has a strong, durable backing not subject to rot and that the facing is adequately bonded to the backing to withstand the intended use. A burlap drag, attached to the pan float on a transverse screed, may be used instead of the carpet drag.

E. Temperature Recording Equipment

For mass concrete operations or as otherwise specified, use strip chart temperature recording devices, recording maturity meters in accordance with Tex-426-A, or other compliance-confirmed devices that are accurate to within ±2°F within the range of 32 to 212°F.

F. Artificial Heating Equipment

Use artificial heating equipment as necessary for maintaining the concrete temperatures as specified in Section 3.2G.11 Placing Concrete in Cold Weather.

G. Sawing Equipment

Use sawing equipment capable of cutting grooves in completed bridge slabs and top slabs of direct-traffic culverts. Provide grooves that are 1/8 to 3/16 in. deep and nominally 1/8 in. wide. Groove spacing may range from 5/8 to 1 in. Use sawing equipment capable of cutting grooves in hardened concrete to within 18 in. of the barrier rail or curb.

H. Spraying Equipment

Use mechanically powered pressure sprayers, either air or airless, with appropriate atomizing nozzles for the application of membrane curing. Mechanically driven spraying equipment, adaptable to the rail system used by the screeds, may be used for applying membrane curing to bridge slabs. If compliance-confirmed, use hand-pressurized spray equipment equipped with 2 or 3 fan-spray nozzles. Ensure that the spray from each nozzle overlaps the spray from adjacent nozzles by approximately 50%.

I. Concrete Testing Equipment

Provide testing equipment for use as determined by the COR.

3.2 CONSTRUCTION

Before starting work, obtain compliance-confirmation for proposed construction methods.

Compliance-confirmation of construction methods and equipment does not relieve the Contractor’s responsibility for safety or correctness of methods, adequacy of equipment, or completion of work in full accordance with the Contract.

Unless otherwise shown on the plans, it is the Contractor’s option to perform testing on structural concrete (structural classes of concrete are identified in Table 5 of Section 03 04 21 Hydraulic Cement Concrete to determine the in-situ strength to address the schedule restrictions in Section 3.2A Schedule Restrictions. The COR may require the Contractor to perform this testing for concrete placed in cold weather. For Contractor-performed testing, make enough test specimens to ensure that strength requirements are met for the operations listed in Section 3.2A Schedule Restrictions. Make at least 1 set of test specimens for each element cast each day. Cure these specimens under the same conditions as the portion of the structure involved for all stages of construction. Ensure safe handling, curing, and storage of all test specimens. Provide testing personnel, and sample and test the hardened concrete in accordance with Section 03 04 21 “Hydraulic Cement Concrete” Pg. 16 of 18 Paragraph G. The maturity method, Tex-426-A, may be used for in-situ strength determination for schedule restrictions if compliance-confirmed. Coring will not be allowed for in-situ strength determination for schedule restrictions. Provide the COR the opportunity to witness all testing operations.

Report all test results to the COR.

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If the Contractor does not wish to perform schedule restriction testing, the COR’s 7-day lab-cured tests, performed in accordance with Section 03 04 21 “Hydraulic Cement Concrete” Page 17 of 18 Paragraph 5, “Adequacy and Acceptance of Concrete” will be used for schedule restriction determinations. The COR may require additional time for strength gain to account for field curing conditions such as cold weather.

A. Schedule Restrictions

Unless otherwise shown on the plans, construct and open completed structures to traffic with the following limitations:

1. Setting Forms

Attain at least 2,500 psi compressive strength before erecting forms on concrete footings supported by piling or drilled shafts, or on individual drilled shafts. Erect forms on spread footings and culvert footings after the footing concrete has aged at least 2 curing days as defined in Section 3.2J Curing Concrete. Place concrete only after the forms and reinforcing steel have been inspected by the

COR.

Support tie beam or cap forms by falsework on previously placed tie beams only if the tie beam concrete has attained a compressive strength of 2,500 psi and the member is properly supported to eliminate stresses not provided for in the design. Maintain curing as required until completion of the curing period.

Place superstructure forms or falsework on the substructure only if the substructure concrete has attained a compressive strength of 3,000 psi.

2. Removal of Forms and Falsework

Keep in place weight-supporting forms and falsework for bridge components and culvert slabs until the concrete has attained a compressive strength of 2,500 psi in accordance with Section 3.2K Removal of Forms and Falsework. Keep all forms for mass placements defined in Section 3.2G.14 Mass Placements, in place for 4 days following concrete placement.

3. Placement of Superstructure Members

Do not place superstructure members before the substructure concrete has attained a compressive strength of 3,000 psi.

4. Longitudinal Screeding of Bridge Slabs

Place a longitudinal screed directly on previously placed concrete slabs to check and grade an adjacent slab only after the previously placed slab has aged at least 24 hr. Place and screed the concrete after the previously placed slabs have aged at least 48 hr. Maintain curing of the previously placed slabs during placement.

5. Staged Placement of Bridge Slabs on Continuous Steel Units

When staged placement of a slab is required, ensure that the previously placed concrete attains a compressive strength of 3,000 psi before placing the next stage placement. Multiple stages may be placed in a single day if compliance-confirmed.

6. Storage of Materials on the Structure

Obtain compliance-confirmation to store materials on completed portions of a structure once a compressive strength of 3,000 psi has been attained. Maintain proper curing if materials will be stored on structures before completion of curing.

7. Placement of Equipment and Machinery

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Do not place erection equipment or machinery on the structure until the concrete has attained the design strength specified in Section 03 04 21 “Hydraulic Cement Concrete” Pg 8 of 18 Paragraph 3.1 Construction, “Classification and Mix Design”, unless otherwise compliance-confirmed.

8. Carting of Concrete

Once the concrete has attained a compressive strength of 3,000 psi, it may be carted, wheeled, or pumped over completed slabs. Maintain curing during these operations.

9. Placing Bridge Rails

Reinforcing steel and concrete for bridge rails may be placed on bridge slabs once the slab concrete has attained a compressive strength of 3,000 psi. If slipforming methods are used for railing concrete, ensure the slab concrete has attained its design strength specified in Section 03 04 21 “Hydraulic Cement Concrete” Pg 8 of 18 Paragraph 3.1 Construction, “Classification and Mix Design”,” before placing railing concrete.

10. Opening to Construction Traffic

Bridges and direct-traffic culverts may be opened to all construction traffic when the design strength specified in Section 03 04 21 “Hydraulic Cement Concrete” Pg 8 of 18 Paragraph 3.1 Construction, “Classification and Mix Design”,” has been attained if curing is maintained.

11. Opening to Full Traffic

Bridges and direct-traffic culverts may be opened to the traveling public when the design strength specified in Section 03 04 21 “Hydraulic Cement Concrete” Pg 8 of 18 Paragraph 3.1 Construction, “Classification and Mix Design”, has been attained for all structural elements including railing subject to impact from traffic, when curing has been completed for all slabs, and when the concrete surface treatment has been applied as directed by COR. Obtain compliance-confirmation before opening bridges and direct-traffic culverts to the traveling public. Other noncritical structural and nonstructural concrete may be opened for service upon the completion of curing unless otherwise specified or directed.

12. Post-Tensioned Construction

For structural elements designed to be post-tensioned ensure that strength requirements on the plans are met for stressing and staged loading of structural elements.

13. Backfilling

Backfill in accordance with Section 31 31 60, “Excavation and Backfill for Structures”.

B. Plans for Falsework and Forms

Submit 2 copies of plans for falsework and forms for piers, superstructure spans over 20

ft. long, bracing systems for girders when the overhang exceeds 3 ft. 6 in., and bridge widening details. Submit similar plans for other units of the structure as directed. Show all essential details of proposed forms, falsework, and bracing. Have a licensed professional COR design, seal, and sign these plans. COR compliance-confirmation is not required, but the COR reserves the right to request modifications to the plans. The Contractor is responsible for the adequacy of these plans.

C. Falsework

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Design and construct falsework to carry the maximum anticipated loads safely, including wind loads, and to provide the necessary rigidity. Submit details in accordance with Section 3.2B Plans for Falsework and Forms.

Design job-fabricated falsework assuming a weight of 150 pcf for concrete, and include a liveload allowance of 50 psf of horizontal surface of the form. Do not exceed 125% of the allowable stresses used byTxDOT for the design of structures.

For commercially produced structural units used in falsework, do not exceed the manufacturer’s maximum allowable working loads for moment and shear or end reaction.

Include a liveload allowance of 35 psf of horizontal form surface in determining the maximum allowable working load for commercially produced structural units.

Provide timber that is sound, in good condition, and free from defects that would impair its strength. Provide timber that meets or exceeds the species, size, and grade requirements in the submitted falsework plans.

Provide wedges made of hardwood or metal in pairs to adjust falsework to desired elevations to ensure even bearing. Do not use wedges to compensate for incorrectly cut bearing surfaces.

Use sills or grillages that are large enough to support the superimposed load without settlement. Take precautions to prevent settling of the supporting material unless the sills or grillages are founded on solid rock, shale, or other hard materials.

Place falsework that cannot be founded on a satisfactory spread footing on piling or drilled shafts with enough bearing capacity to support the superimposed load without settlement. Drive falsework piling to the required resistance determined by the applicable formula in section 03 03 04 “Driving Piling.” Design drilled shafts for falsework to carry the superimposed load using both skin friction and point bearing.

Weld as directed by COR. Securely brace each falsework bent to provide the stiffness required, and securely fasten the bracing to each pile or column it crosses.

Remove falsework when it is no longer required or as indicated on the submitted falsework plan. Pull or cut off foundations for falsework at least 2 ft. below finished ground level. Completely remove falsework, piling, or drilled shafts in a stream, lake, or bay to the compliance-confirmed limits to prevent obstruction to the waterway.

D. Forms

Submit formwork plans in accordance with Section 3.2B Plans for Falsework and Forms.

1. General

Except where otherwise specified or permitted, provide forms of either timber or metal.

Design forms for the pressure exerted by a liquid weighing 150 pcf. Take the rate of concrete placement into consideration in determining the depth of the equivalent liquid. Include a liveload allowance of 50 psf of horizontal surface for job-fabricated forms. Do not exceed 125% of the allowable stresses used by the TxDOT for the design of structures.

For commercially produced structural units used for forms, do not exceed the manufacturer’s maximum allowable working loads for moment and shear or end reaction. Include a liveload allowance of 35 psf of horizontal form surface in determining the maximum allowable working load for commercially produced structural units.

Provide steel forms for round columns unless otherwise compliance-confirmed.

Provide commercial form liners for imprinting a pattern or texture on the concrete surface as shown on the plans.

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Provide forming systems that are practically mortar-tight, rigidly braced, and strong enough to prevent bulging between supports, and maintain them to the proper line and grade during concrete placement. Maintain forms in a manner that prevents warping and shrinkage. Do not allow offsets at form joints to exceed 1/16 in.

For forms to be left in place, use only material that is inert, nonbiodegradable, and nonabsorptive.

Attachment of forms or screed supports for bridge slabs to steel I-beams or girders may be by welding subject to the following requirements:

• Do not weld to tension flanges or to areas indicated on the plans.

• Weld in as directed by COR.

Take into account:

• deflections due to cast-in-place slab concrete and railing shown in the dead load deflection diagram in the setting of slab forms,

• differential beam or girder deflections due to skew angles and the use of certain stay-in-place slab forming systems, and

• deflection of the forming system due to the wet concrete.

For bridge approach slabs, securely stake forms to line and grade and maintain in position. Rigidly attach inside forms for curbs to the outside forms.

Construct all forms to permit their removal without marring or damaging the concrete. Clean all forms and footing areas of any extraneous matter before placing concrete. Provide openings in forms if needed for the removal of laitance or foreign matter

Treat the facing of all forms with bond-breaking coating of composition that will not discolor or injuriously affect the concrete surface. Take care to prevent coating of the reinforcing steel.

Complete all preparatory work before requesting permission to place concrete.

If the forms show signs of bulging or sagging at any stage of the placement, cease placement and remove the portion of the concrete causing this condition immediately if necessary. Reset the forms and securely brace them against further movement before continuing the placement.

2. Timber Forms

Provide properly seasoned good-quality lumber that is free from imperfections that would affect its strength or impair the finished surface of the concrete. Provide timber or lumber that meets or exceeds the requirements for species and grade in the submitted formwork plans.

Maintain forms or form lumber that will be reused so that it stays clean and in good condition. Do not use any lumber that is split, warped, bulged, or marred or that has defects that will produce inferior work, and promptly remove such lumber from the work.

Provide form lining for all formed surfaces except:

• the inside of culvert barrels, inlets, manholes, and box girders;

• the bottom of bridge slabs between beams or girders;

• surfaces that are subsequently covered by backfill material or are completely enclosed; and

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• any surface formed by a single finished board or by plywood.

Provide form lining of an compliance-confirmed type such as masonite or plywood. Do not provide thin membrane sheeting such as polyethylene sheets for form lining.

Use plywood at least 3/4 in. thick. Place the grain of the face plies on plywood forms parallel to the span between the supporting studs or joists unless otherwise indicated on the submitted form drawings.

Use plywood for forming surfaces that remain exposed that meets the requirements for B-B Plyform Class I or Class II Exterior of the U.S. Department of Commerce Voluntary Product Standard PS 1.

Space studs and joists so that the facing form material remains in true alignment under the imposed loads.

Space wales closely enough to hold forms securely to the designated lines, scabbed at least 4 ft. on each side of joints to provide continuity. Place a row of wales near the bottom of each placement.

Place facing material with parallel and square joints, securely fastened to supporting studs.

For surfaces exposed to view and receiving only an ordinary surface finish as defined in Section 03 35 00 Concrete Finishing, place forms with the form panels symmetrical (long dimensions set in the same direction). Make horizontal joints continuous.

Make molding for chamfer strips or other uses of materials of a grade that will not split when nailed and that can be maintained to a true line without warping. Dress wood molding on all faces. Unless otherwise shown on the plans, fill forms at all sharp corners and edges with triangular chamfer strips measuring 3/4 in. on the sides.

To hold forms in place, use metal form ties of an compliance-confirmed type or a satisfactory substitute of a type that permits ease of removal of the metal. Cut back wire ties at least 1/2 in. from the face of the concrete.

Use devices to hold metal ties in place that are able to develop the strength of the tie and adjust to allow for proper alignment. Entirely remove metal and wooden spreaders that separate the forms as the concrete is being placed.

Provide adequate clean-out openings for narrow walls and other locations where access to the bottom of the forms is not readily attainable.

3. Metal Forms

Requirements for timber forms regarding design, mortar-tightness, filleted corners, beveled projections, bracing, alignment, removal, reuse, and wetting also apply to metal forms except that metal forms do not require lining unless specifically noted on the plans.

Use form metal thick enough to maintain the true shape without warping or bulging. Countersink all bolt and rivet heads on the facing sides. Design clamps, pins, or other connecting devices to hold the forms rigidly together and to allow removal without damage to the concrete. Use metal forms that present a smooth surface and that line up properly. Keep metal free from rust, grease, and other foreign materials.

4. Form Supports for Overhang Slabs

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Form supports that transmit a horizontal force to a steel girder or beam or to a prestressed concrete beam are permitted provided a satisfactory structural analysis has been made of the effect on the girder or beam as indicated in the submitted formwork plans.

When overhang brackets are used on prestressed concrete beam spans with slab overhangs not exceeding 3 ft 6 in., use beam bracing as indicated in the plans. For spans with overhangs exceeding this amount, use additional support for the outside beams regardless of the type of beam used. Submit details of the proposed bracing system in accordance with Section 3.2B Plans for Falsework and Forms.

Punch or drill holes full size in the webs of steel members for support of overhang brackets, or torch-cut them to 1/4 in. under size and ream them full size. Do not burn the holes full size. Leave the holes open unless otherwise shown on the plans. Never fill the holes by welding.

E. Drains

Install and construct weep holes and roadway drains as shown on the plans.

F. Placing Reinforcement

Place reinforcement as provided in Section 03 21 10, “Reinforcing Steel.” Do not weld reinforcing steel supports to I-beams or girders or to reinforcing steel except where shown on the plans.

Place post-tensioning ducts in accordance with the compliance-confirmed prestressing details and in accordance with Section 03 04 26, “Prestressing.” Keep ducts free of obstructions until all post-tensioning operations are complete.

G. Placing Concrete

Give the COR sufficient advance notice before placing concrete in any unit of the structure to permit the inspection of forms, reinforcing steel placement, and other preparations.

Follow the sequence of placing concrete shown on the plans or specified.

Do not place concrete when impending weather conditions would impair the quality of the finished work. If conditions of wind, humidity, and temperature are such that concrete cannot be placed without the potential for shrinkage cracking, place concrete in early morning or at night or adjust the placement schedule for more favorable weather. Consult the evaporation rate nomograph in the Portland Cement Association’s Design and Control of Concrete Mixtures for shrinkage cracking potential. When mixing, placing, and finishing concrete in non-daylight hours, adequately illuminate the entire placement site as compliance-confirmed.

If changes in weather conditions require protective measures after work starts, furnish adequate shelter to protect the concrete against damage from rainfall or from freezing temperatures as outlined in this Item. Continue operations during rainfall only if compliance-confirmed. Use protective coverings for the material stockpiles. Cover aggregate stockpiles only to the extent necessary to control the moisture conditions in the aggregates.

Allow at least 1 curing day after the concrete has achieved initial set before placing strain on projecting reinforcement to prevent damage to the concrete.

1. Placing Temperature

Place concrete according to the following temperature limits for the classes of concrete defined in Section 03 04 21 “Hydraulic Cement Concrete” Pg. 8 of 18, Paragraph 3.2 Construction, “Classification and Mix Design”:

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• Place Class C, F, H, K, or SS concrete only when its temperature at time of placement is between 50 and 95°F. Increase the minimum placement temperature to 60°F if ground-granulated blast furnace (GGBF) slag is used in the concrete.

• When used in a bridge slab or in the top slab of a direct-traffic culvert, place Class CO, DC, or S concrete only when its temperature at the time of placement is between 50 and 85°F. Increase the minimum placement temperature to 60°F if GGBF slag is used in the concrete. The maximum temperature increases to 95°F if these classes are used for other applications.

• Place Class A, B, and D concrete only when its temperature at the time of placement is greater than 50°F.

• Place mass concrete, defined by Section 3.2G.14 Mass Placements, only when its temperature at the time of placement is between 50 and 75°F.

2. Transporting Time

Place concrete delivered in agitating trucks within 60 min. after batching. Place concrete delivered in non-agitating equipment within 45 min. after batching.

Revise the concrete mix design as necessary for hot weather or other conditions that contribute to quick setting of the concrete. Submit for compliance-confirmation a plan to demonstrate that these time limitations can be extended while ensuring the concrete can be properly placed, consolidated, and finished without the use of additional water.

3. Workability of Concrete

Place concrete with a slump as specified in Section 03 04 21 Hydraulic Cement Concrete Table 8, “Slump Requirements”. Concrete that exceeds the maximum slump will be rejected. Water may be added to the concrete before discharging any concrete from the truck to adjust for low slump provided that the maximum mix design water– cement ratio is not exceeded. Do not add water or chemical admixtures after any concrete has been discharged.

4. Transporting Concrete

Use a method and equipment capable of maintaining the rate of placement shown on the plans or required by this Item to transport concrete to the forms.

Transport concrete by buckets, chutes, buggies, belt conveyors, pumps, or other methods.

Protect concrete transported by conveyors from sun and wind to prevent loss of slump and workability. Shade or wrap with wet burlap pipes through which concrete is pumped as necessary to prevent loss of slump and workability.

Arrange and use chutes, troughs, conveyors, or pipes so that the concrete ingredients will not be separated. When necessary to prevent segregation, terminate such equipment in vertical downspouts. Extend open troughs and chutes, if necessary, down inside the forms or through holes left in the forms.

Keep all transporting equipment clean and free from hardened concrete coatings.

Discharge water used for cleaning clear of the concrete.

5. Preparation of Surfaces

Thoroughly wet all forms, prestressed concrete panels, T-beams, and concrete box beams on which concrete is to be placed before placing concrete on them.

Remove any remaining puddles of excess water before placing concrete. Provide

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Ensure that the subgrade or foundation is moist before placing concrete for bridge approach slabs or other concrete placed on grade. Lightly sprinkle the subgrade if dry.

6. Expansion Joints

Construct joints and devices to provide for expansion and contraction in accordance with plan details and the requirements of this Section.

Prevent bridging of concrete or mortar around expansion joint material in bearings and expansion joints.

Use forms adaptable to loosening or early removal in construction of all open joints and joints to be filled with expansion joint material. To avoid expansion or contraction damage to the adjacent concrete, loosen these forms as soon as possible after final concrete set to permit free movement of the span without requiring full form removal.

When the plans show a Type A joint, provide preformed fiber joint material in the vertical joints of the roadway slab, curb, median, or sidewalk, and fill the top 1 in.

with the specified joint sealing material unless noted otherwise. Install the sealer in accordance with and the manufacturer’s recommendations.

Use light wire or nails to anchor any preformed fiber joint material to the concrete on 1 side of the joint.

Ensure that finished joints conform to the plan details with the concrete sections completely separated by the specified opening or joint material.

Remove all concrete within the joint opening soon after form removal and again where necessary after surface finishing to ensure full effectiveness of the expansion joint.

7. Construction Joints

A construction joint is the joint formed by placing plastic concrete in direct contact with concrete that has attained its initial set. Monolithic placement means that the manner and sequence of concrete placing does not create a construction joint.

Make construction joints of the type and at the locations shown on the plans. Do not make joints in bridge slabs not shown on the plans unless compliance-confirmed. Additional joints in other members are not permitted without compliance-confirmation. Place authorized additional joints using details equivalent to those shown on the plans for joints in similar locations.

Unless otherwise required, make construction joints square and normal to the forms. Use bulkheads in the forms for all vertical joints.

Thoroughly roughen the top surface of a concrete placement terminating at a horizontal construction joint as soon as practical after initial set is attained.

Thoroughly clean the hardened concrete surface of all loose material, laitance, dirt, and foreign matter, and saturate it with water. Remove all free water and moisten the surface before concrete or bonding grout is placed against it.

Draw forms tight against the existing concrete to avoid mortar loss and offsets at joints.

Coat the joint surface with bonding mortar, grout, epoxy, or other material as indicated in the plans or other Items. Provide Type V epoxy per DMS-6100, “Epoxies and Adhesives,” for bonding fresh concrete to hardened concrete.

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Place the bonding epoxy on a clean, dry surface, and place the fresh concrete while the epoxy is still tacky. Place bonding mortar or grout on a surface that is saturated surface-dry, and place the concrete before the bonding mortar or grout dries. Place other bonding agents in accordance with the manufacturer’s recommendations.

8. Handling and Placing

Minimize segregation of the concrete and displacement of the reinforcement when handling and placing concrete. Produce a uniform dense compact mass.

Do not allow concrete to free-fall more than 5 ft. except in the case of drilled shafts, thin walls such as in culverts, or as allowed by other Items. Remove any hardened concrete splatter ahead of the plastic concrete.

Fill each part of the forms by depositing concrete as near its final position as possible. Do not deposit large quantities at 1 point and run or work the concrete along the forms.

Deposit concrete in the forms in layers of suitable depth but not more than 36 in.

deep unless otherwise permitted.

Avoid cold joints in a monolithic placement. Sequence successive layers or adjacent portions of concrete so that they can be vibrated into a homogeneous mass with the previously placed concrete before it sets. When re-vibration of the concrete is shown on the plans, allow at most 1 hr. to elapse between adjacent or successive placements of concrete except as otherwise allowed by an compliance-confirmed placing procedure. This time limit may be extended by 1/2

hr. if the concrete contains at least a normal dosage of retarding admixture.

Use an compliance-confirmed retarding agent to control stress cracks and cold joints in placements where differential settlement and setting time may induce cracking.

9. Consolidation

Carefully consolidate concrete and flush mortar to the form surfaces with immersion type vibrators. Do not use vibrators that operate by attachment to forms or reinforcement except where compliance-confirmed on steel forms.

Vibrate the concrete immediately after deposit. Systematically space points of vibration to ensure complete consolidation and thorough working of the concrete around the reinforcement, embedded fixtures, and into the corners and angles of the forms. Insert the vibrator vertically where possible except for slabs where it may be inserted in a sloping or horizontal position. Vibrate the entire depth of each lift, allowing the vibrator to penetrate several inches into the preceding lift.

Do not use the vibrator to move the concrete to other locations in the forms. Do not drag the vibrator through the concrete. Thoroughly consolidate concrete along construction joints by operating the vibrator along and close to but not against the joint surface. Continue the vibration until the concrete surrounding reinforcements and fixtures is completely consolidated. Hand-spade or rod the concrete if necessary to ensure flushing of mortar to the surface of all forms.

10. Installation of Dowels and Anchor Bolts

Install dowels and anchor bolts by casting them in-place or by grouting with grout, epoxy, or epoxy mortar unless noted otherwise. Form or drill holes for grouting.

Drill holes for anchor bolts to accommodate the bolt embedment required by the plans. Make holes for dowels at least 12 in. deep unless otherwise shown on the plans. When using grout or epoxy mortar, make the diameter of the hole at least

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greater than the dowel or bolt diameter.

Thoroughly clean holes of all loose material, oil, grease, or other bond-breaking substance, and blow them clean with filtered compressed air. Ensure that holes are in a surface dry condition when epoxy type material is used and in a surface moist condition when hydraulic cement grout is used. Develop and demonstrate for compliance-confirmation a procedure for cleaning and preparing the holes for installation of the dowels and anchor bolts. Completely fill the void between the hole and dowel or bolt with grouting material. Follow exactly the requirements for cleaning outlined in the product specifications for prepackaged systems.

For cast-in-place or grouted systems, provide hydraulic cement grout in accordance with Section 03 04 21 “Hydraulic Cement Concrete” Paragraph 2.6 “Mortar and Grout”, epoxy, epoxy mortar, or other prepackaged grouts as compliance-confirmed. Provide a Type III epoxy per DMS-6100, “Epoxies and Adhesives,” when neat epoxy is used for anchor bolts or dowels. Provide Type VIII epoxy per DMS-6100 when an epoxy grout is used. Provide grout, epoxy, or epoxy mortar as the binding agent unless otherwise indicated on the plans.

Provide other anchor systems as required in the plans.

11. Placing Concrete in Cold Weather

Protect concrete placed under weather conditions where weather may adversely affect results. Permission given by the COR for placing during cold weather does not relieve the Contractor of responsibility for producing concrete equal in quality to that placed under normal conditions. If concrete placed under poor conditions is unsatisfactory, remove and replace it as directed at Contractor’s expense.

Do not place concrete in contact with any material coated with frost or having a temperature of 32°F or lower. Do not place concrete when the ambient temperature in the shade is below 40°F and falling unless compliance-confirmed.

Concrete may be placed when the ambient temperature in the shade is 35°F and rising or above 40°F.

Provide and install recording thermometers, maturity meters, or other suitable temperature measuring devices to verify that all concrete is effectively protected as follows:

• Maintain the temperature of the top surface of bridge slabs and top slabs of direct-traffic culverts at 50°F or above for 72 hr. from the time of placement and above 40°F for an additional 72 hr.

• Maintain the temperature at all surfaces of concrete in bents, piers, culvert walls, retaining walls, parapets, wingwalls, bottoms of bridge slab or culvert top slabs, and other similar formed concrete at 40°F or above for 72 hr. from the time of placement.

• Maintain the temperature of all other concrete, including the bottom slabs (footings) of culverts, placed on or in the ground above 32°F for 72 hr. from the time of placement.

Use additional covering, insulated forms, or other means and, if necessary, supplement the covering with artificial heating. Avoid applying heat directly to concrete surfaces. Cure as specified in Section 3.2J Curing Concrete, during this period until all requirements for curing have been satisfied.

When impending weather conditions indicate the possible need for temperature protection, have on hand all necessary heating and covering material, ready for use, before permission is granted to begin placement.

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12. Placing Concrete in Hot Weather

Use an compliance-confirmed retarding agent in all concrete for superstructures and top slabs of directtraffic culverts, except concrete containing GGBF slag, when the temperature of the air is above 85°F unless otherwise directed.

Keep the concrete at or below the maximum temperature at time of placement as specified in Section 3.2G.1 Placing Temperature. Sprinkle and shade aggregate stockpiles or use ice, liquid nitrogen systems, or other compliance-confirmed methods as necessary to control the concrete temperature.

13. Placing Concrete in Water

Deposit concrete in water only when shown on the plans or with compliance-confirmation. Make forms or cofferdams tight enough to prevent any water current passing through the space in which the concrete is being deposited. Do not pump water during the concrete placing or until the concrete has set for at least 36 hr.

Place the concrete with a tremie or pump, or use another compliance-confirmed method, and do not allow it to fall freely through the water or disturb it after it is placed. Keep the concrete surface approximately level during placement.

Support the tremie or operate the pump so that it can be easily moved horizontally to cover all the work area and vertically to control the concrete flow.

Submerge the lower end of the tremie or pump hose in the concrete at all times.

Use continuous placing operations until the work is complete.

For concrete to be placed under water, design the concrete mix in accordance with Section 03 04 21, “Hydraulic Cement Concrete,” with a minimum cement content of 650 lb. per cubic yard. Include an anti-washout admixture in the mix design as necessary to produce a satisfactory finished product.

14. Mass Placements

Mass placements are defined as placements with a least dimension greater than or equal to 5 ft., or designated on the plans. For monolithic mass placements, develop and obtain compliance-confirmation for a plan to ensure the following during the heat dissipation period:

• the temperature differential between the central core of the placement and the exposed concrete surface does not exceed 35°F and

• the temperature at the central core of the placement does not exceed 160°F.

Base this plan on the equations given in the Portland Cement Association’s Design and Control of Concrete Mixtures. Cease all mass placement operations and revise the plan as necessary if either of the above limitations is exceeded.

Include a combination of the following elements in this plan:

• selection of concrete ingredients including aggregates, gradation, and cement types, to minimize heat of hydration;

• use of ice or other concrete cooling ingredients;

• use of liquid nitrogen dosing systems;

• controlling rate or time of concrete placement;

• use of insulation or supplemental external heat to control heat loss;

• use of supplementary cementing materials; or

• use of a cooling system to control the core temperature.

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Furnish and install 2 sets of temperature recording devices, maturity meters, or other compliance-confirmed equivalent devices at designated locations. Use these devices to simultaneously measure the temperature of the concrete at the core and the surface. Maintain temperature control methods for 4 days unless otherwise compliance-confirmed. Maturity meters may not be used to predict strength of mass concrete.

15. Placing Concrete in Foundation and Substructure

Do not place concrete in footings until the depth and character of the foundation has been inspected and permission has been given to proceed.

Placing of concrete footings upon seal concrete is permitted after the cofferdams are free from water and the seal concrete cleaned. Perform any necessary pumping or bailing during the concreting from a suitable sump located outside the forms.

Construct or adjust all temporary wales or braces inside cofferdams as the work proceeds to prevent unauthorized construction joints.

When footings can be placed in a dry excavation without the use of cofferdams, omit forms if compliance-confirmed, and fill the entire excavation with concrete to the elevation of the top of footing.

Place concrete in columns monolithically between construction joints unless otherwise directed. Columns and caps or tie beams supported on them may be placed in the same operation or separately. If placed in the same operation, allow for settlement and shrinkage of the column concrete by placing it to the lower level of the cap or tie beam, and delay placement between 1 and 2 hr. before proceeding with the cap or tie beam placement.

16. Placing Concrete in Box Culverts

Where the top slab and walls are placed monolithically in culverts more than 4 ft.

in clear height, allow between 1 and 2 hr. to elapse before placing the top slab to allow for settlement and shrinkage in the wall concrete.

Accurately finish the footing slab at the proper time to provide a smooth uniform surface. Finish top slabs that carry direct-traffic as specified in this Item. Give top slabs of fill type culverts a float finish.

17. Placing Concrete in Superstructure

Unless otherwise shown on the plans, place simple span bridge slabs without transverse construction joints by using either a self-propelled transverse finishing machine or a mechanical longitudinal screed. For small placements or for unusual conditions such as narrow widening, variable cross-slopes, or transitions, use of manually operated screeding equipment may be permitted.

Support the screed adequately on a header or rail system stable enough to withstand the longitudinal or lateral thrust of the equipment. Adjust the profile grade line as necessary to account for variations in beam camber and other factors to obtain the required slab thickness and concrete cover over the slab reinforcement. Set beams and verify their surface elevations in a sufficient number of spans so that when adjustment is necessary, the profile grade line can be adjusted over suitable increments to produce a smooth riding surface. Take dead load deflection into account in setting the grades of headers and rail systems. Use construction joints, when required or permitted for slab placements on steel or prestressed concrete beams, as shown on the plans. Before placing concrete on steel girder or truss spans, release falsework under the spans and swing the spans free on their permanent supports.

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Make 1 or more passes with the screed over the bridge slab segment before placing concrete on it to ensure proper…