Section 2413. Surfacing and Repair and Overlay of Bridge Floors.

2413.01 DESCRIPTION.
Surfacing bridge floors shall consist of placing a wearing course on a prepared surface, and other necessary work shown in the contract documents or specified herein.

Repair and overlay of bridge floors shall consist of removing concrete from the existing surface, replacing and overlaying with new concrete, and other necessary work shown in the contract documents or as specified. When structural repairs are included in the project, Class C or Class D concrete, as specified, may be mixed using equipment meeting requirements of Article 2413.03, B. The concrete mixture used for the overlay may be used for the repair; the water and consistency shall be as specified in Article 2403.03, A. Unless otherwise provided in the contract documents, overlay shall accomplish a raise of the existing roadway surface and shall cover the entire concrete floor surface, including those areas to be repaired. Bridge floor repair and overlay shall be classified as follows:

A. Class A Bridge Floor Repair.
Class A bridge floor repair shall consist of removing floor concrete below the level described for Bridge Floor Overlay, but less than full depth, transporting the existing concrete removed from the project, and replacing the excavated volume with concrete to a level bounding the Bridge Floor Overlay classification. Lower limit for Class A Bridge Floor Repair shall be to suitable existing concrete, as determined by the Engineer, but to at least the level of the top of the top reinforcing steel.

B. Class B Bridge Floor Repair.
Class B bridge floor repair shall consist of removing floor concrete below the level described for Bridge Floor Overlay for the full depth of the floor, transporting the existing concrete removed from the project, and replacing the excavated volume with concrete to a level bounding the Bridge Floor Overlay classification.

C. Bridge Floor Overlay.
Bridge floor overlay shall consist of removing floor concrete to a depth 1/4 inch (5 mm) below the existing, finished surface, except at drains and elsewhere as noted in the contract documents, transporting the existing concrete removed from the project, and overlaying with a concrete course of a depth designated. Thickness of the concrete overlay shall be measured from a level 1/4 inch (5 mm) below the original surface to a final raised surface as shown. Where removal to a level lower than 1/4 inch (5 mm) below the original surface is necessary because of surface fixtures, the minimum thickness of abutting overlay shall be 3/4 inch (20 mm) and shall be tapered to the full designated thickness.

Unless otherwise specified, the work shall be done using either Portland cement concrete or latex modified concrete, at the Contractor's option.

2413.02 MATERIALS.
All materials shall meet requirements for the respective items in Division 41.

Only one brand of cement shall be used during an individual placement. Class O concrete mixtures shall not contain fly ash, Type IP cement, or Type I(PM) cement.

Sections 4110, and 4115 shall apply to the aggregates. Only those coarse aggregates specifically allowed by Article 4115.065 for this work shall be used.

A. Portland Cement Concrete.
Class O PCC is required and it shall meet the requirements of Materials I.M. 529 and the following requirements:

The slump, measured in accordance with Materials I.M. 317 shall be 3/4 inch (20 mm) with a maximum of 1 inch (25 mm) and no minimum requirement. Testing for slump of concrete from a continuous mixer shall commence within 2 to 4 minutes after the concrete is discharged.

The intended air entrainment of the finished concrete is 6%, but the air content of fresh, unvibrated concrete at the time of placement, as determined by Materials I.M. 318 shall be 6.5%, with a maximum variation of ± 1.0%.

Grout for bonding new concrete to previously placed concrete shall consist of equal parts by weight (mass) of Portland cement and fine aggregate for concrete mixed with sufficient water to form a stiff slurry. The consistency shall be so that the slurry can be applied with a stiff brush or broom to the previously placed concrete in a thin, even coating that will not run or puddle in low spots. An equivalent grout of Portland cement and water, to be applied by pressure spray may be substituted with approval of the Engineer. For sealing vertical joints between adjacent lanes and at the curbs, this grout shall be thinned to paint consistency.

B. Latex Modified Concrete.
The latex modified concrete shall be a workable mixture having the following properties or limits:
 

PROPERTIES OF LATEX MODIFIED CONCRETE
Material or Property	Type 2 Concrete
Cement (parts by weight (mass)) Fine Aggr. (parts by weight (mass)) Coarse Aggr. (parts by weight (mass)) Latex Emulsion Admixture (gal/bag (L/kg) cement) Air Content of Plastic Mix, % (Note 1) Slump, inches (mm), maximum (Notes 1 and 2)	1.0 (1.0) 2.5 (2.5) 2.0 (2.0) 3.5 (0.3) 3-6 5 (125)
Note 1. Following sampling of the discharged, normally mixed material: the commencement of the tests shall be delayed from 4 to 4.5 minutes. Note 2. Water may be added to obtain slump within the prescribed limits. Concrete with a slump less than 3 inches (75 mm) may be rejected if it is not placed satisfactorily and with a closed tight surface.

The formulated latex admixture shall be a nontoxic, film forming, polymeric emulsion in water to which all stabilizers have been added at the point of manufacture and shall be homogeneous and uniform in composition.

The physical properties of the latex modifier shall conform to the following requirements:

PHYSICAL PROPERTIES OF LATEX MODIFIER
Polymer type Stabilizers (a) Latex* (b) Portland cement composition Percent solids Weight per gallon (lb at 25°C) (Mass per liter (kg at 25°C) Color	Styrene butadiene Nonionic surfactants Poly dimethyl siloxane 46.0 - 49.0 8.4 (1.0) White
*Chloride content of the latex must be less than 0.5%.

Latex admixture to be stored shall be kept in suitable enclosures which will protect it from freezing and from prolonged exposure to temperatures in excess of 85°F (30°C). Containers of latex admixture may be stored at the bridge site for a period not to exceed 10 calendar days. Such stored containers shall be covered completely with suitable insulating blanket material to avoid excessive temperatures.

2413.03 EQUIPMENT.
Equipment used shall be subject to approval of the Engineer and shall comply with the following:

A. Preparation Equipment.
Preparation equipment shall be of the following types:

1. Sawing Equipment.
Sawing equipment shall be capable of sawing concrete to the specified depth.

2. Sandblasting or Shot Blasting Equipment.
Sandblasting or shot blasting equipment shall be capable of removing rust, oil, and concrete laitance from the existing surface of the bridge floor.

3. Power Driven Hand Tools.
Power driven hand tools will be permitted with the following restrictions:

a. Jack Hammers heavier than nominal 30 pound class (with a mass greater than 14 kg) shall not be used.

b. Jack Hammers or mechanical chipping tools shall not be operated at an angle in excess of 45 degrees measured from the surface of the slab.

c. Chipping Hammers heavier than a nominal 15 pound (with a mass greater than 7 kg) class shall not be used.

4. Hand Tools.
Hand tools such as hammers and chisels shall be provided for removal of final particles of unsound concrete or to achieve the required depth.

5. High Pressure Water Blasting Equipment.
High pressure water blasting equipment shall be capable of removing rust, oil, concrete laitance, and unsound concrete from the existing surface of the bridge floor.

B. Proportioning and Mixing Equipment.

1. Proportioning and mixing equipment for Portland cement concrete shall meet requirements of Article 2001.20, D, and Article 2001.21, C. In addition, the device for proportioning water shall be accurate within 1.0%, and the mixer shall be a construction or stationary concrete mixer of the rotating paddle type. A continuous mixer used in conjunction with volumetric proportioning, described above, may be used.

Sufficient mixing capacity or mixers shall be provided for either type of mixture to permit the intended quantity to be placed without interruption.

2. Proportioning and mixing equipment for latex modified concrete shall be of a self contained, mobile continuous mixing type subject to the following:

a. The mixer shall have storage for sufficient bulk cement, fine and coarse aggregate, latex modifier, and water to produce, on the site, not less than 6 cubic yards (4 m³) of concrete. The mixer shall be capable of metering materials and producing uniform concrete.

b. The mixer shall be capable of positive measurement of cement being introduced into the mix. A cement meter register, visible at all times, shall indicate this quantity.

c. The mixer shall provide positive control of the flow of water and latex emulsion into the mixing chamber. Water use shall be indicated by a recording water meter. The flow shall be readily adjustable to provide for minor variations in aggregate moisture.

d. The mixer shall be capable of being calibrated to automatically proportion and blend all components of indicated composition on a continuous or intermittent basis, as required by the finishing operation, and shall discharge mixed material through a conventional chute directly in front of the finishing machine.

C. Placing and Finishing Equipment.
Placing and finishing equipment shall include adequate hand tools for placement of the mixture and for working it down to approximately the correct level for striking off with the screed. A self propelled finishing machine will be required for all surfacing and overlays, and the front screed shall be designed to consolidate the mixture to be placed to 100% of the rodded density. The machine shall operate on supporting rails which are adequately secured to the previously placed surface and are adjustable to the correct profile without shimming, which do not deflect under the load of the machine, and which may be removed without damage to the edge of the new surface that is to remain in place. When placing the mixture in a lane abutting a previously completed lane, that side of the finishing machine adjacent to the completed lane shall be suitably equipped to travel on the completed lane. The finishing machine shall be inspected and approved before work is started on each project.

The finishing machine shall meet the following additional requirements for the type of mixture to be placed:

1. Portland Cement Concrete.
The finishing machine shall meet requirements of Article 2412.06 and shall have a mechanical strike off to provide a uniform thickness of mixture in front of the screed designed to consolidate the mixture by vibration, as specified. The bottom face of this screed shall be at least 5 inches (125 mm) wide with a turned up or rounded leading edge to minimize tearing of the surface of the plastic concrete. Each screed shall have an effective weight (mass) of at least 75 pounds for each square foot (365 kg/m²) of bottom face area. Each screed shall be provided with positive control of the vertical position, the angle of tilt, and the shape of the crown. Design of the finishing machine together with appurtenant equipment shall be such that positive machine screeding of the plastic concrete will be obtained within 1 inch (25 mm) of the face of the existing curbs. The length of the screed shall be sufficient to extend at least 6 inches (150 mm) beyond the line where a saw cut is intended to form the edge of a subsequent placement section, and shall overlap the sawed edge of a previously placed course at least 6 inches (150 mm). The finishing machine shall be capable of forward and reverse motion under positive control. Provision shall be made for raising the screeds to clear the screeded surface for traveling in reverse.

2. Latex Modified Concrete.
The finishing machine shall be self propelled and shall be capable of forward and reverse movement under positive control. Provision shall be made for raising all screeds to clear the screeded surface for traveling in reverse. The finishing machine shall be capable of finishing the surface to within 1 foot (0.3 m) of the edges of the area being placed.

The screeds shall be provided with positive control of the vertical position.

Internal vibration equipment will be required for consolidation at the edges of the placement.

D. General.
The overall combination of labor and equipment for proportioning, mixing, placing, and finishing the new surface shall be of such minimum capability as to meet the following requirements except when noted otherwise in the contract documents.
 

MINIMUM CAPACITY AND LABOR REQUIREMENTS
Total Surface Area per Bridge, sq. yd. (m2)	Minimum Requirement, cu. yd. per hour (m3 per hour)
0-328 (0-274) 329-492 (274.1-410) 493-656 (410.1-550) over 656 (over 550.1)	1.0 (0.8) 1.5 (1.2) 2.0 (1.6) 2.5 (2.0)

The finishing machine shall be designed so that when the mixture is being mixed and placed at the specified minimum rate, under normal operating conditions, the elapsed time between depositing the mixture on the floor and final screeding shall not exceed 10 minutes.

2413.04 PREPARATION OF SURFACE FOR SURFACING.
Material for test holes and all loose, disintegrated, or unsound concrete shall be removed from the bridge floor, as designated by the Engineer.

The thickness of all new concrete above the prepared surface shall be as specified in the contract documents. The clearance shall be checked in the following manner before concrete is placed.

A filler block having a thickness 1/4 inch (5 mm) less than the designated thickness shall be attached to the bottom of the screed; with screed guides in place, the screed shall be passed over the area to be concreted. As an alternate to passage of the finishing machine, an approved template, supported by the screed guides, may be passed over the area to be concreted. If the filler block does not clear the area to be concreted, the profile of the new surface shall be adjusted as approved by the Engineer.

In preparation for placement of new concrete, the surface shall be sandblasted or shot blasted, followed by an air blast. This cleaning shall remove all dirt, oil, and other foreign material, as well as any unsound concrete, laitance, or loose material from the surface and edges against which the surface mixture is to be placed. It is desired that the surface be roughened by the cleaning to provide satisfactory bond with the surfacing mixture. Metal floor drains and areas of the curb or railing above the proposed surface shall be protected from the cleaning.

For the PCC mixture, it is not intended or desired that existing concrete, prepared for surfacing, be presaturated before grout and new concrete is placed. The prepared surface shall be dry to allow some absorption of the grout.

For the latex modified concrete, the surface of existing concrete shall be saturated but free of standing water.

2413.05 PREPARATION OF SURFACE FOR REPAIR AND OVERLAY.
Concrete shall be removed from each area, designated in the contract documents or by the Engineer, to a depth and in a manner consistent with the classification for that area. Areas as shown in the contract documents are based on the best information available; actual areas will be determined by the Engineer.

A. Class A Bridge Floor Repair.
Concrete may be removed by chipping, shot blasting, hydro blasting, or by a combination of these, except that final clean up, in any case, shall be by use of hand tools. Class A repair removal shall be considered to start 1/4 inch (5 mm) below the existing surface, but this shall not preclude removal coincidental with preparation for overlay. Removal for Class A repair shall extend at least to the level of the top reinforcing bars, and the removal shall extend deeper, as necessary, to remove unsound concrete.

All reinforcing bars and newly exposed concrete shall be thoroughly cleaned by sandblasting or shot blasting. Where bond between existing concrete and reinforcing steel has been destroyed, the concrete adjacent to the bar shall be removed to a depth that will permit new concrete to bond to the entire periphery of the exposed bar. A minimum of 3/4 inch (20 mm) clearance shall be required around the bar. Care shall be exercised to prevent cutting, stretching, or damaging any exposed reinforcing steel. The Engineer may require enlarging a designated area should inspection indicate deterioration of concrete or corrosion of reinforcing beyond the limits previously designated.

For Class A repair and in preparation for bridge deck overlay, the surface may also be prepared or partially prepared using a high pressure water system, at the Contractor's option. Procedures shall be as recommended by the equipment manufacturer, subject to approval of the Engineer and within such limitations as may be imposed.

Additional removal may be required to provide for test holes.

B. Class B Bridge Floor Repair.
Within all areas designated for Class B repair, and any designated areas of Class A repair in which the depth of the remaining sound concrete is less than 50% of the original depth of the bridge floor, all concrete shall be removed. Designated Class A repair areas shall be measured as Class B Bridge Floor Repair when full depth removal is required. At the direction of the Engineer, limited areas of removal greater than 50% of the floor thickness, such as beneath reinforcing, may be allowed; these limited areas of excess depth will be measured as Class A Bridge Floor Repair. Concrete shall be removed by jack hammer, chipping hammer, or by a combination of scarifying and chipping hammer, except that the final removal at the periphery of Class B repair areas shall be accomplished by 15 pound (7 kg) jack hammer, chipping hammer, or hand tools. Class B repair removal shall be considered to start 1/4 inch (5 mm) below the existing surface, but this shall not preclude removal coincidental with preparation for overlay. All exposed reinforcing bars and newly exposed concrete shall be thoroughly cleaned by sandblasting or shot blasting. Care shall be exercised to prevent cutting, stretching, or damaging exposed reinforcing.

Forms shall be provided to enable placement of new concrete in the full depth opening. The forms shall preferably be suspended from existing reinforcing bars by wire ties. Forms may, in the case of large area openings, be supported by blocking from the beam flanges. Forms will in all cases be supported by elements of the existing superstructure unless specifically noted or shown otherwise in the contract documents.

C. Bridge Floor Overlay.
The entire existing concrete floor area shall be uniformly scarified or prepared to a depth of 1/4 inch (5 mm), except over areas of Class A and Class B repair where the 1/4 inch (5 mm) removal may be coincidental with operations for repair removal. Removal to a greater depth will be required at drains and elsewhere, as noted in the contract documents.

D. General.
The thickness of concrete above the prepared surface or reinforcing steel shall be at least 3/4 inch (20 mm) and shall be greater if specified in the contract documents. The clearance shall be checked in the following manner before concrete is placed:

A filler block having a thickness 1/8 inch (3 mm) less than the overlay thickness shall be attached to the bottom of the screed; with screed guides in place, the screed shall be passed over the area to be concreted. As an alternate to passage of the finishing machine, an approved template, supported by the screed guides, may be passed over the overlay area. Where the intended clearance does not allow use of this method, a string line or other means shall be used, subject to approval of the Engineer. All old concrete which does not have sufficient clearance shall be removed. All reinforcing steel which does not have sufficient clearance shall be depressed and fastened down. It may be necessary to remove concrete beneath some reinforcement to permit depressing the reinforcement adequately. The minimum clear distance around these bars for placement of new concrete shall be 3/4 inch (20 mm).

Areas from which concrete has been removed shall be kept free of slurry produced by wet sawing of concrete joints. All of this slurry shall be removed from prepared areas before new concrete is placed.

Hand tools shall be used to remove final particles of concrete or to achieve the required depth. The entire surface, including curbs and exposed reinforcement, against which new concrete is to be placed shall be sandblasted or shot blasted. The cleaning shall be of an extent to remove all dirt, oil, and other foreign material, as well as any unsound concrete. Immediately before applying grout in preparation for placement of new concrete, the surface shall be cleaned with air blast. For the Portland cement concrete, it is not intended or desired that existing concrete, prepared for repair or overlay be presaturated with water before grout and new concrete is placed. The prepared surface shall be dry to allow some absorption of the grout.

At the time of placement of either PCC or latex modified concrete, the area shall be clean and the reinforcement free of rust; rust forming because of dew on clean reinforcement overnight will not be considered objectionable, but reinforcement with a greater amount of rust shall be subject to recleaning before the concrete is placed. The area shall be cleaned by air blast before the concrete is placed.

For latex modified concrete, the surface shall be flushed with water and kept wet for at least 1 hour before concrete placement. Puddles of free water shall be removed before covering with concrete.

2413.06 PROPORTIONING AND MIXING.
The mixture shall be proportioned and mixed at the project site. Ready mixed concrete will not be approved.

The water reducing admixture for improved workability of Portland cement concrete shall be incorporated and mixed into the concrete in accordance with the manufacturer's recommendations and the Engineer's instructions.

A. Stationary Mixer.
When a construction or stationary mixer is used, proportioning and mixing shall be in accordance with applicable provisions of Article 2403.06.

B. Continuous Mixing Equipment.
When continuous mixing equipment is used, the following shall apply:

1. Mobile continuous mixers shall accurately proportion all materials for the specified mixture.

2. The proportioning equipment for each material shall be calibrated in the presence of the inspector, or the Engineer may accept a previous calibration and require satisfactory verification checks only, at the settings indicated by the previous calibration.

3. The proportioning equipment shall be operated at the speed recommended by the manufacturer during calibration, checks, or normal operation.

4. Continuous mixers shall be recharged at the site.

5. The Contractor may make yield checks or other checks and the inspector will cooperate in such checking.

6. The materials shall be mixed in an approved mixer within 1 mile (2 km) of the site of placement. They shall be mixed in accordance with the specified requirements for the equipment used. The mixture, as discharged from the mixer, shall be uniform in composition and consistency.

7. For latex modified concrete, mixing capability shall be such that finishing operations can proceed at a steady pace with final finishing completed before the formation of the plastic surface film.

2413.07 PLACING AND FINISHING.
An approved finishing machine will be required as specified in Article 2413.03, C. Supporting rails upon which the finishing machine travels shall be placed outside the area to be surfaced. Provisions for anchorage of supporting rails shall provide for horizontal and vertical stability; positive anchorage may be required by the Engineer. A hold down device shot into concrete will not be permitted unless the concrete is to be subsequently surfaced. Hold down devices of other types leaving holes in exposed areas will be approved provided the holes remaining are grouted full. Plans for anchoring support rails and the mixture placing procedure shall be submitted to the Engineer for approval.

For latex modified concrete, transverse bulkheads, equal in depth to the thickness of the surface, shall be installed to the required grade and profile prior to placing the concrete.

The locations of longitudinal joints may be shown in the contract documents. If not shown, the locations shall be subject to approval of the Engineer, and the approval will be based on avoiding joints in the wheel paths as much as practical.

In order to insure a junction with properly consolidated concrete, the surface course previously placed shall be sawed to a straight and vertical edge at longitudinal and transverse joints and removed before adjacent concrete is placed. The Engineer will determine the extent of such removal.

The Contractor shall take every reasonable precaution to secure a smooth riding bridge deck. Prior to placement operations, the Contractor shall review the equipment, procedures, personnel, and previous results with the Engineer, and the inspection procedures will be reviewed to assure coordination. Precautions shall include the following:

Assurance that concrete can be produced and placed within the specified limits, continuously and with uniformity.

After finishing, the Contractor shall check the surface with a 10 foot (3 m) straightedge; causes for irregularities exceeding 1/8 inch (3 mm) should be eliminated, and corrections should be made, if practical.

Each placement will be checked in accordance with Section 2317 the day following placement or before another section is placed.

After the surface has been cleaned and immediately before placing Portland cement concrete, a thin coating of bonding grout shall be scrubbed into the dry, prepared surface. At the Contractor's option, the grout may be sprayed onto the surface in a manner subject to approval of the Engineer. Care shall be exercised to insure that all parts receive a thorough, even coating and that no excess grout is permitted to collect in pockets. The rate of progress in applying grout shall be limited so that the grout does not become dry before it is covered with new concrete. If the grout becomes dry, it shall be removed by sandblasting and new grout applied.

Concrete shall be placed in a continuous operation. The new concrete shall be manipulated and mechanically struck off slightly above final grade. It shall then be mechanically consolidated to 100% of the rodded density, with a minus tolerance of 2%, and screeded to final grade. The rodded density will be determined in accordance with Materials I.M. 358.

An internal vibrator shall be used for consolidation at the curb side, and along the longitudinal construction joint adjacent to a previously constructed lane.

The following applies to repair and overlay work:

Although repair classes are considered to begin 1/4 inch (5 mm) below the original concrete surface, repair concrete shall be placed monolithically with the overlay course, except as described for larger areas of Class B repair. Fresh concrete, 3 inches (75 mm) or more in thickness, shall be vibrated internally in addition to the surface screed vibration.

Areas of Class B repair 2 square yards (2 m²) or greater shall have floor forms supported by beams or stringers. These larger areas of Class B repair shall have individual concrete replacement to the lower boundary for the superimposed overlay. Floor repair concrete, described in Article 2413.02, or Class D structural concrete, meeting requirements of Sections 2403 and 2412, may be used for the partial placements. Surfaces of these individual placements are to be left rough, and all placements for each construction stage shall be complete before the overlay course is started. If a full depth repair is staged, a beveled keyway not less than 1 1/2 inch by 3 inches (35 mm by 75 mm) shall be provided at the vertical joint. Concrete placement and reinforcing support shall comply with applicable portions of these specifications except as modified by the contract documents. The partial placement shall have a 72 hour cure as described for the overlay surface. After the cure, partial placements are to be surface dried, sandblasted or shot blasted, and cleaned prior to the application of the overlay course or grout.

When a tight, uniform surface has been achieved, the surface shall be given a suitable grooving, by hand methods, similar to that described in Article 2301.16, A, with the following exceptions:

• Grooving shall be transverse to the centerline of roadway.
• Transverse grooving shall be randomly spaced from 3/4 inch to 1 5/8 inches (20 mm by 40 mm) with no more than 50% of the spacings exceeding 1/4 inches (30 mm) with a minimum of four different spacings in a 2 foot (0.6 m) width.

This operation shall be done at a time and manner that the desired texture will be achieved while minimizing displacement of the larger aggregate particles. The texture should not extend into the areas within approximately 2 feet (0.5 m) of curbs. As soon as finishing has been completed, all vertical joints with adjacent concrete shall be sealed by painting with thinned grout.

A. Interstate and Primary Projects.
Transverse grooving or tining in plastic concrete of bridge deck overlay (and bridge approach overlay when included in a bridge deck overlay project) will not be allowed. Longitudinal grooves shall be cut into the hardened concrete surfaces using a mechanical cutting device. Longitudinal grooving shall be done after surface correction grinding.

Longitudinal grooves shall be 1/8 inch +/- 1/64 inch (3 mm +/- 0.4 mm) in width, 1/8 inch +1/32 inch or -1/16 inch (3 mm +0.8 mm or -1.6 mm) in depth, and the grooves shall be uniformly spaced at 3/4 inch (19 mm) intervals measured from center to center of groove.

Longitudinal grooving on bridge deck overlay and double reinforced bridge approach overlay sections shall not be within the area approximately 2 feet (0.6 m) adjacent to the curbs and shall terminate approximately 6 inches (150 mm) from bridge joints. Longitudinal grooving of single reinforced and non-reinforced bridge approach sections shall not be applied within 6 inches (150 mm) of the edge of the outside lane lines.

For staged bridge deck overlay and bridge approach overlay construction the Contractor may cut longitudinal grooves in the hardened concrete at the end of each construction stage or wait until all stages have been completed. If the Contractor elects to delay cutting of the longitudinal grooves until completion of all stages, the concrete deck overlay and bridge approach overlay for any stage opened to traffic shall receive an interim coarse broom finish during placement. Within 30 calendar days following completion of the last stage of the project the Contractor shall establish temporary lane closures to accomplish longitudinal grooving for all stages. The interim coarse broom finish will not be allowed as a surface texture when opened to traffic over a winter season. If the interim coarse broom texture is present and the Contractor is not in a position to finish all stages of the project, longitudinal grooving shall be cut into the hardened concrete in order to establish an acceptable driving surface texture for the winter season.

B. Other Projects.
When a tight, uniform surface has been achieved, the surface shall be given a suitable grooving, by hand methods, similar to that described in Article 2301.16, A, with the following exceptions:

• Grooving shall be transverse to the centerline of roadway.
• Transverse grooving shall be randomly spaced from 3/4 inch to 1 5/8 inches (20 mm by 40 mm) with no more than 50% of the spacings exceeding 1/4 inches (30 mm) with a minimum of four different spacings in a 2 foot (0.6 m) width.

This operation shall be done at a time and manner that the desired texture will be achieved while minimizing displacement of the larger aggregate particles. The texture should not extend into the areas within approximately 2 feet (0.5 m) of curbs. As soon as finishing has been completed, all vertical joints with adjacent concrete shall be sealed by painting with thinned grout.

Screed rails and/or construction dams shall be separated from newly placed latex modified concrete by passing a pointing trowel along their inside face. Care shall be exercised to assure that this trowel cut is made for the entire depth and length of rails or dams after the mixture has stiffened sufficiently and that it does not flow back.

Section 2317 shall apply to smoothness of the completed deck overlay for Primary projects and when specifically required for other projects.

2413.08 CURING.
Immediately after final finishing, the area finished shall be covered with white pigmented curing compound, meeting requirements of Article 4105.05, applied at a rate of not more than 135 square feet per gallon (3.3 m²/L) . As soon as it can be placed without marring the surface, a  The first layer of prewetted burlap shall be placed on the concrete, and within 10 minutes after finishing. Burlap shall be prewetted with sufficient water, prior to placement, to prevent absorption of moisture from the concrete surface. tThe concrete shall be cured as provided in the following paragraphs:

For Portland cement concrete, the surface shall be cured for at least 72 hours. For the first 24 hours, the burlap shall be kept continuously wet by means of an automatic sprinkling or wetting system. After 24 hours, the Contractor may cover the wet burlap with a layer of 4 mil (100 µm) polyethylene film for a minimum of 48 hours in lieu of using the sprinkling or wetting system. The wet burlap shall be applied within 30 minutes after the concrete has been deposited on the floor, except when the surface will be excessively marred by so doing, as directed by the Engineer. If the concrete is revibrated because of failure to meet density requirements with initial vibration, this the time for placement of prewetted burlap will be extended 15 minutes. Failure to apply wet burlap within the required time shall be cause for rejecting the work so affected. Surface concrete in the rejected area shall be removed and replaced at no additional cost to the Contracting Authority.

For latex modified concrete, the surface shall be cured by wet burlap for at least 24 hours and be air cured for an additional 48 hours. Within 1 hour of covering with wet burlap, a layer of 4 mil (100 µm) polyethylene film shall be placed on the wet layer for the required 24 hour period for curing. The curing material shall then be removed for an additional 48 hour air cure. Burlap polyethylene sheets may be substituted for the polyethylene film with the approval of the Engineer. It is the nature of the latex modifier to form a plastic film at the surface upon drying, usually within 25 minutes in hot, dry weather. It is the intent of this specification that this film be protected from drying and cracking by prompt covering with wet burlap.

At the Contractor's option, partial depth concrete for Class B repair may be cured with white pigmented curing compound only. When this curing is completed, the surface shall be sandblasted and allowed to dry, and the existing concrete in that vicinity shall be sandblasted, prior to placement of the overlay course.

2413.09 SEALING.
The tops and traffic sides of curbs, retrofit barrier rails, and concrete barrier rails shall be sealed in accordance with Article 2403.21, D. In addition, for Portland cement concrete floor overlay, the sealer shall be applied along each gutter line, extending 1 foot (0.3 m) onto the roadway. Other areas requiring concrete sealer may be designated in the contract documents or by the Engineer.

2413.10 LIMITATIONS OF OPERATIONS.
Work on the surface shall not be commenced until the lower course meets the requirements of Article 2403.19, B.

If traffic is to be maintained during the construction period of this contract, it will be noted in the contract documents. The Contractor shall provide traffic controls that are required by the contract documents.

Night work will be permitted. When daytime temperatures exceed 85°F (30°C) the Engineer may require placement of latex modified concrete to be made at night or in the early morning hours if a satisfactory surface finish is not being achieved. In either case, adequate lights for nighttime work shall be furnished at the direction of the Engineer by the Contractor without additional compensation. The Engineer shall be given reasonable notice.

A construction dam or bulkhead shall be installed in case of major delay in the placement operation. During minor delays of 1 hour or less, the end of the placement may be protected from drying with several layers of wet burlap.

Adequate precautions shall be taken to protect freshly placed concrete from sudden or unexpected rain. The Engineer may order removal of any concrete damaged by rainfall.

Screed rails may be removed at any time after the concrete has taken initial set. Adequate precaution shall be taken during screed removal to protect the edge of the new surface from damage.

Concrete shall not be placed adjacent to a surface course less than 36 hours old, however, this restriction does not apply to a continuation of placement in a lane or strip beyond a joint in the same lane or strip.

If concrete placement is stopped or delayed for a period of 90 minutes or more, further placement shall be discontinued and may resume only after a period of not less than 12 hours. This restriction does not prohibit continuation of placement provided a gap is left in the lane or strip; the gap shall be sufficient in length for the finishing machine to clear previously placed concrete.

Preparation work will not be allowed in a lane or strip until the lane is closed to traffic. In areas where there is no traffic, preparation of the area may be started in a lane or strip adjacent to newly placed surface the day following its placement. If this work is started before the end of the 72 hour curing period, the work will be restricted as follows:

Sawing or other operations shall interfere with the curing process for the minimum practical time only, and in the immediate work area only, and the curing shall be resumed promptly.

Chipping hammers heavier than a nominal 15 pound (with a mass greater than 7 kg) class shall not be used.

Air compressors shall be operated on the floor only directly over the piers.

Loads other than construction equipment shall not be permitted on any portion of the bridge floor that has undergone preparation and prior to placement and curing of new concrete.

Traffic shall not be permitted on a finished surface course until 72 hours after placement. At temperatures below 55°F (13°C), the Engineer may require a longer waiting time.

PCC shall not be placed when the air or floor temperature is below 40°F (4°C). Latex modified concrete shall not be placed when the air or floor temperature is below 45°F (7°C); however, it may be placed when these temperatures are 45°F (7°C) and a rising temperature is predicted.

Concrete mixture shall not be placed after October 1 and prior to April 1 without written approval of the Engineer.

2413.11 METHOD OF MEASUREMENT.
Bridge Floor Surfacing will be computed by the Engineer in square yards (square meters) from measurements of the areas surfaced. For bridge floor surfacing, concrete removal for test wells may be required by the Engineer. This removal will not be measured for payment.

Class A Bridge Floor Repair, Class B Bridge Floor Repair, and Bridge Floor Overlay will be computed by the Engineer in square yards (square meters) from measurements of the areas repaired or overlaid.

Sealing, as required in Article 2413.09, will not be measured separately for payment.

Longitudinal Grooving in concrete shall be measured in accordance with Article 2412.11.

2413.12 BASIS OF PAYMENT.
For the performance of acceptable work, measured as provided above, the Contractor will be paid the contract unit price in accordance with the following provisions: