511 Concrete for Structures

Materials (511.02)

Item 511.02 requires all concrete above the ground line in a given substructure unit or all concrete for any given superstructure be made of aggregate of the same kind and color, except upon permission of the Engineer.


Concrete (511.03)

Concrete for structures will be Class QC 1, QC 2, QC 3, or QC 4, or as specified in the Contract documents. The mix design and control are outlined in Item 499 and in Supplement 1126, except when modified as specified. 

The Contractor has to submit, in writing, the Department accepted Job Mix Formula (JMF) to the Engineer, for a check for conformance to contract requirements, at least ten days before placing concrete.


Quality Control Requirements and Mass Concrete (511.04)

When the contract requires Quality Control/Quality Assurance, (QC/QA) Concrete, in addition to the JMF, the Contractor is required to submit a Quality Control Plan (QCP) for the work and perform quality control testing of the concrete as specified in C&MS 455. Also per C&MS 455, the Department or its representative will perform Quality Assurance sampling and testing as specified or as deemed necessary.

 For quality assurance, the Engineer will make acceptance test cylinders as follows:

1.      Structure over 20 foot span. A set of test cylinders from each 200 cubic yards of concrete or fraction thereof incorporated into the work each day.

2.      Structures of 20 foot span or less. At least one set of test cylinders for each 50 cubic yards of concrete.

The Contractor must provide a sealed, temperature controlled, Concrete Cylinder Curing Box (CCCB) capable of holding at least twelve 4-inch x 8-inch cylinders for both quality control and quality assurance cylinders.

Mass Concrete Requirements (511.04.A)

Mass Concrete is defined as concrete components with a minimum dimension of 5 feet. In C&MS 499, QC-4 is the designated class of concrete for Mass Concrete mix designs. In addition to submitting a mix design,  per C&MS 499.03 and Supplement 1126, a Quality Control Plan per C&MS 455, the Contractor is also required to submit a Thermal Control Plan (TCP) to the Engineer, for a check for conformance to contract requirements, at least ten days before placing concrete. The purpose of the TCP is for the Contractor to explain how they plan to prevent shrinkage cracking in Mass Concrete placements.

The TCP must control the placement of mass concrete so that:

1.      The highest maximum internal temperature in the concrete is not greater than 160 ºF.

2.      The maximum differential concrete temperature does not exceed  36 ºF.

over 28 days from the time of concrete placement.

The TCP shall include:

1.      Duration and method of curing.

2.      Procedures to control concrete temperature at the time of placement. The mix shall contain no frozen pieces of ice after blending and mixing components.

3.      Methods and equipment used for controlling temperature differentials.

4.      Temperature sensor types, locations and installation details. As a minimum, concrete temperatures shall be monitored at the calculated hottest location, on at least 2 outer faces, 2 corners, and top surfaces.

5.      Temperature monitoring and recording system; operation plan; recording and reporting plan with example output; and a remedial action plan.

6.      Criteria, (allowable air and concrete temperatures and time), for form removal to control the maximum temperature differential.

The Contractor may propose maximum differential temperature limits based on strength gain with time as an alternate to the maximum differential concrete temperature criteria.

All cracking of mass concrete where the differential temperatures exceed 36ºF is the responsibility of the Contractor.

The Contractor must monitor and document all temperature sensors during the cure period. If the maximum limit or differential temperature limits are exceeded, the Contractor must take immediate action to correct the problem and revise and resubmit the TCP. The Department will determine if the proposed repair methods are acceptable or if removal is required.


Mixing of Concrete (511.05)


All concrete used in structures must contain 6 ± 2 percent entrained air as specified in 499.  An air determination should be made for each part of the structure. This determination should be made as early as possible on the first load of concrete.  For substructure concrete, as many additional air tests as necessary should be made to ensure required air content.  For superstructure concrete, an air test should be made for each load of concrete used.  Concrete containing less than the specified amount of air may have the air content increased by the addition of an air entrained agent and an additional 30 revolutions of the concrete mixer drum at mixing speed. 

Concrete that is pumped can lose air as the concrete passes through the pump.  Therefore, it is important that air tests be made at the point of placement, after the concrete passes through the pump.

Accepted chemical admixtures may be incorporated into concrete to improve workability and to extend the setting time.  Chemical admixtures must meet the requirement of 705.12 that specifies they meet the requirements of ASTM C 494 chemical admixtures.  These admixtures are as follows.

·         TYPE A - Water reducing

·         TYPE B - Retarding

·         TYPE C - Accelerating

·         TYPE D - Water reducing and retarding

·         TYPE E - Water reducing and accelerating

·         TYPE F - Water reducing, high range

·         TYPE G - Water reducing, high range, and retarding

The type of admixture is optional with the Contractor.  However, when the air temperature is 60 °F  (16 °C) or higher at the time of placement of superstructure concrete, and the span is over 20 feet (6.1 m), the addition of a Type B or D admixture is required.


Slump (511.06)

The slump of the workable concrete shall be maintained within the range specified in 499.03.  An occasional load exceeding the nominal slump, but within the maximum, may be used, provided immediate steps are taken to adjust the slump of succeeding loads.  Before concrete exceeding the nominal slump range may be used, the Contractor or supplier must take positive action to reduce the slump of following loads. 


The results of the air tests together with yield tests are shown on the back of Form TE-45.  The Ready Mixed Concrete Plant Ticket must show the number of revolutions at mixing speed.  A mixer’s rated RPM for mixing speed and agitation speed will be listed with the operating data on the mixer.  The mixers must be checked to see that they are operating at the rated speeds.  The structure unit in which that load of concrete is placed should be noted on the ticket.  A full list of the required data to appear on a batch ticket is listed in Table 499.07-1.


Placing Concrete (511.07)

The Contractor must submit to the Engineer a description of proposed placing procedures. If the contract requires QC/QA Concrete, this procedure would be included in the QCP.

Advance Notice of Placing Concrete

The Contractor must notify the Engineer at least 24 hours in advance of placing concrete.  Review this provision with the Contractor near the start of work on a structure. This ensures a clear understanding regarding the stage of completed work necessary to permit inspection before approval to proceed.  The need for all or part of the 24 hours will depend on the amount of additional inspection required to ensure that the reinforcing steel has been properly placed and that the forms are in the correct location.

Placement Tolerances

The Contractor is required to place and finish concrete to the lines and grades shown in the plans. The concrete must provide coverage over or around reinforcing steel as described in 509.04. Table 511.07-1 lists placement tolerances from plan dimensions.

Evaporation Rate

In an effort to reduce or eliminate drying shrinkage cracks in the superstructure concrete, the concrete should not be placed when the evaporation rate of water from the freshly placed concrete is too high.  Use the graph (Figure 1) in C&MS Item 511.07 to check the evaporation rate.

The Contractor should check the evaporation rate immediately before the placement of superstructure concrete begins.  The evaporation rate should also be checked if there is a change in temperature, humidity, or wind speed during the placement of superstructure concrete. Wind speed can have the greatest effect on the evaporation rate; therefore, changes in wind speed should be more closely monitored.  Many times, during the summer months, it will be necessary to place superstructure concrete at night in order to comply with the evaporation rate limits. 

In addition to the evaporation rate, superstructure concrete is not allowed to be placed when the ambient air temperature is 85 °F (30 °C) or higher or is predicted to go above 85 °F (30 °C) during placement.  The temperature of the concrete is not allowed to exceed 95 °F (35 °C) during the mixing and placement.  Many times it is necessary for the Contractor to reduce the temperature of the mixing water and/or aggregates in order to control the temperature of the concrete.

Evaporation retardant is mostly water and its use is not permitted.  Be aware that evaporation retardants are also marketed as finishing agents, but under either name their use is prohibited.


Several methods may be used to convey the concrete to the forms.  Any method that ensures placement of concrete of the proper consistency without segregation is satisfactory.  Usually ready-mix trucks with open chutes, buckets, drop chutes, and concrete pumps are used to place substructure concrete.  Open chutes must be sloped sufficiently to allow concrete of the proper consistency to flow readily.  Drop chutes may be maneuvered to distribute the concrete, but the delivery end must be kept vertical.  Concrete is deposited as near as possible to its final position with as short of a vertical drops as practical but not over 5 feet (1.5 m).

Consolidation of concrete by the vibration method is required for structures.  Spud vibrators generally are used and should have a workman assigned exclusively to each vibrator.  The vibrator should be pushed into and pulled out of the freshly deposited concrete slowly and as vertical as possible.  For narrow sections, the vibrator may be applied to the sides of the forms or a form vibrator may be used.  Establish a pattern of placing and vibrating that provides practically horizontal surfaces and uniform vibrator coverage.  Generally a vibrator can consolidate concrete in approximately a 4-inch to 8-inch radius depending on the type of concrete.  Visual inspection of consolidation is a two-step process of one, seeing the surface of the concrete flatten out, and two, seeing air bubbles come to the surface within the vibration radius.  Therefore, a uniform coverage pattern must be used to ensure uniform consolidation.


Where concrete will be placed to bedrock, the rock should be free of mud and cleared of all loose rock or other accumulations.  Soil serving as the footing bottom should be sufficiently dry and stable so that it will not be interspersed in the concrete.

Concrete may occasionally be placed in water; however, with the exception of drilled shafts, concrete is not to be placed under water.  When concrete is placed in water, placement should begin in one corner of the forms and continue against the previously deposited concrete until full height of the footing is attained.  Full height should be carried forward, displacing the water ahead and out a small opening in the opposite corner of the forms.  Vibration of the concrete should be kept well back of the water.  Concrete must never be deposited in running water since it will cause separation of cement from the mixture. If pumping is controlling the water level, the pumping may be halted or reduced immediately after the concreting is complete, so that the water level rises slowly and inundates the footing to provide the cure.

When the plans require a concrete seal, or it becomes necessary for the Contractor to use a seal to stop the upward flow of water, the concrete must be deposited under water in a manner that minimizes separation of the cement.  This type of seal is sometimes referred to as a mud mat.  A concrete seal is deposited in a compact mass with a minimum of disturbance from the water it displaces.  When a tremie or concrete pump is used, the end of the pump or tremie hose or tube must be plugged prior to lowering into the water and kept filled during placement.  Failure to keep the tremie or pump filled with concrete during placement could result in water entering into the tremie tube or pump hose.  This will result in the cement being washed from the aggregate.  The Contractor’s plans for the mix and placement should be reviewed prior to the pour.  Where the Contractor elects to use a seal, it is his responsibility to choose a thickness and methods that produce satisfactory results.

Piers and Abutments

Concrete for backwalls above the approach slab seat shall not be placed until the abutments have been backfilled to within 2 feet (610 mm) of the bridge seat elevation.  

When expansion joints are involved, the backwall should not be placed until after the superstructure concrete is placed.  As the superstructure concrete is placed, the beams will grow in length as the camber decreases.  If the backwall is placed prior to placing the superstructure concrete, the required opening in the end dam will be lost as the beams grow in length.

The tops of backwalls that become roadway surface require special methods for setting the grade.  Although the recommended methods have been used to set the end dams, the elevations can be slightly off grade. Therefore, the tops of the end dams should not be used alone to project the grade for the backwall.  The preferred method of obtaining the correct grade is to place a 10-foot (3.05 m) straightedge as a screed supported on the superstructure concrete and the end dam.   The backwall can be struck to the proper grade.  Grade strips tacked to the backwall form that have their elevations established in a manner described above may be used to establish the grade.  In the event that the grade for the surface of concrete is not flush with the end dam edge bar, it should be finished to the grade established above and edged to a radius equal to the offset where it abuts the edge bar.

After the forms have been stripped from backwalls and before the approach slabs are placed, the top surface of concrete is subject to damage by spalling of the sharp edge on the approach slab side.  Covering the surface with a plank or any other method that will afford equal protection should be provided.

Concrete should never be deposited through closely spaced reinforcing steel where it may accumulate and take set prior to encasement or cause segregation of aggregate.  The bars, such as the top main bars in a pier cap, should temporarily be moved out of the path of the concrete or hopper until the concrete level has reached the vicinity of the bars and then reset.  If the plans require bearings for which anchor bolt holes will be drilled later, the bars must be reset accurately and checked with a template.

Bearing Seats

Bearing areas on abutments and piers must be finished accurately to the plan elevations in order that the deck may be placed on profile grade.  The elevations should be checked accurately when finished to correct possible errors and settlement of the forms containing the original marks.  Take elevations as soon as possible after completion of the substructure units and record them for future reference.

Bearing seats that are high or uneven must be leveled to the proper elevation by bush hammering or grinding and then smoothed with a thin film of Portland cement paste to fill the pitted surface.  Bearing seats that are over 1/8 inch (3 mm) low are leveled as described above and raised to the proper elevation by steel shims placed under the masonry plates. If elastomeric bearings are specified, steel shims should not be placed under the bearing.  In this case, consult the Office of Structural Engineering pertaining to the acceptability of the Contractor’s proposed method of correcting the bearing seat.

Where it is necessary to cut down the bearing area, the lowering is extended approximately 1 inch (25 mm) around the area of the masonry plate and carried full width to the face of the abutment or pier cap for drainage.

Pre-Pour Conference for Placing Concrete for Superstructures

Prior to the scheduled day for deck placement, preferably the day before, a conference should be held to review the plans and preparations for the pour (Forms CA-S-4 and CA-S-6).  The Contractor’s Superintendent and key personnel, together with the Engineer and available inspectors who will be involved, should attend.  At this time, the Superintendent should state his plan of operation, and agreement should be reached with the Engineer on all of the following:

7.      Provision for adequate concrete delivery to ensure continuous placing and to provide sufficient length of workable concrete for proper straight edging.  This includes the number of trucks assigned and an access route where ingress and egress will be maintained at all times.

8.      Spacing of the trucks, especially at the start and end, so that no load will be delayed unduly in discharging or will placing be delayed for lack of concrete.

9.      A system of communicating with the concrete plant to permit ready adjustments in the mix or delivery

10.  Proper tools and equipment on hand have been checked and are in good working order.  A finishing bridge must be used when the deck cannot be reached for proper finishing.

11.  A competent and experienced bridge superintendent who will be in charge and at least two experienced finishers.

12.  Factors that might determine the need for chemical admixtures are explained.

13.  Protection on hand in case of rain or low temperatures.

14.  For decks with hinges, and where it is planned to terminate a pour at the expansion joint over the hinge, concrete placement should proceed in the direction that will load the longer part of the hinged span first.  This will minimize the effects of unequal span loading, unless otherwise specified in the plans.

15.  Properly curing the concrete and placing the wet burlap in a timely manner.

Closure Pour

Many times a bridge deck will be constructed part width at a time to maintain traffic on a portion of the existing or completed structure. At times, an existing structure will be widened by adding at least two beam lines.  A closure pour will be used to account for the differential deflection that will occur between the portion of the deck that has already been placed and has yet to be placed.  This closure pour is important and should be performed.  A closure pour involves a strip of concrete several feet (a meter) or more wide that is not placed until after the deck concrete is placed in both phases.  It is placed the entire length of the deck between the two portions of deck.

When a closure pour is specified, the forms on the second phase of the deck yet to be placed must not be supported by the first phase that has been previously placed.  The reinforcing steel must not be spliced, and cross bracing shall not be placed between phases until the concrete in the second phase has been placed.

Immediately prior to placing the concrete in the closure pour, it is important that the cross bracing between the first two phases be completely installed.  At this time, it is acceptable to support the forms for the closure pour from the two completed adjacent phases.

Setting the Grade for Finishing the Deck

When finishing a deck, setting the grade correctly is paramount for placing a deck on profile grade.  A table of screed rail elevations is shown on the plans for composite box beam bridges, rolled beam, girder, and concrete I beam bridges. Screed elevations should be provided in the plans for all curb lines or deck edges, profile grade points, transverse grade-break lines and phased construction lines for the full length of the bridge. Bearing points, quarter span points, mid-span points and splice points, as well as any additional points required to meet a maximum spacing between points of 25’-0”, should be provided in the plans. Screed elevations above each beam/girder line are no longer required by the ODOT Bridge Design Manual due to the differential deflection between beam/girders. The amount of beam/girder deflection that occurs due to the wet weight of concrete at each screed cross-section will vary based on the span length of each beam/girder, the magnitude of concrete load applied to each beam/girder and the size of each beam/girder cross section.

Screed Elevations are control elevations for concrete deck finishing machines that represent the theoretical deck surface locations prior to deflections caused by deck concrete placement and other anticipated dead loads. Screed elevations are provided to ensure the bridge deck is completed to the correct elevations.

Top of Haunch Elevations represent the theoretical location of the bottom of the deck above the beam/girder haunch prior to deflections caused by deck placement and other anticipated dead loads. Elevations must be taken on the end dams and at every point on the beams required for setting the grade of the screed rail, including points over the piers. There should be no deflections at the bearing points over the piers and abutments, with the maximum deflections occurring at the mid-spans. The Haunch Height (Haunch Fill) equals the Top of Haunch Elevation (Deck Bottom) minus the surveyed Beam Top Elevation. These elevations provide the contractor the means to determine the proper haunch depths for setting deck falsework. See Figure 511.A.


Beam Row


Rear Abut

¼ Pt

½ Pt

¾ Pt

Pier 1


Deck Bot






Beam Top






Haunch Ht







Deck Bot






Beam Top






Haunch Ht







Deck Bot






Beam Top






Haunch Ht







Deck Bot






Beam Top






Haunch Ht







Deck Bot






Beam Top






Haunch Ht







Table 511.A – Determining Haunch Height

This is an acceptable method of recording this information.

The Final Deck Surface Elevations shown in the plans represent the deck surface location after all anticipated dead load deflections have occurred. These elevations should line up with the approach slab and pavement elevations off of the bridge. Whenever the profile grade of the deck is adjusted, this must be considered when setting the grade for the approach slabs and pavement in order to provide a smooth transition. Even though it has not been necessary to adjust the grade, the as-built grade of the deck should be used to establish the grade of the approach slabs, since the actual dead load deflections may vary from the calculated deflections shown on the plans.

Figure 511.A – Deck Elevations and Deflections


Figure 511.B – Screed Points at curb lines, profile grade and grade- breaks


Figure 511.C – Top of Haunch Elevations in Non-Deflected (Unloaded) Position


Differential deflection should be built into the Camber Diagram.


Figure 511.D – Interior Deflection > Exterior Deflection


Will occur with addition of concrete weight. Do not adjust screed rails to increase deck and cover thickness at interior of deck.


Figure 511.E – Interior Deflection < Exterior Deflection


Will occur with addition of concrete weight. Do not adjust screed rails to decrease deck and cover thickness at interior of deck.

Superstructure Framing, Setting Falsework, Setting Screed Rails and Dry Run

The Contractor’s carpenter foreman should use the following procedure when setting the deck falsework, setting the screed rails, and performing the dry run with the Engineer:

1.      Ensure all superstructure framing, (e.g., each intermediate crossframe and diaphragm), is permanently fastened according to C&MS 513.26.

2.      Once beam/girder erection is complete, mark the elevation control locations on the top of the beam/girder flanges.

3.      At each control location, survey and record the top of beam/girder elevation

4.      Calculate the haunch depths at each control location as the difference between the plan Top of Haunch Elevation (Deck Bottom), and the surveyed Beam Top Elevation.

5.      Using the haunch depths and screed elevations, erect the deck falsework. The bottom deck form in the overhangs shall be set by subtracting the deck edge thickness from the nearest screed elevation.

6.      With the falsework in place, mark the screed elevation control locations on the surface of the falsework.

7.      Set the screed rail elevations at control locations given in the plans using the screed elevations provided. Intermediate rail elevations may be determined by stringline between plan specified screed locations.

8.      Once the finishing machine setup is complete, run the unit the full length of the screed rails and back using the machine’s weight to take out any “timber crunch” or formwork settlement. Reset screed rail as necessary.

9.      Locate the finishing machine at each screed rail control location with the carriage moved nearest the screed rail. Measure and record the screed rail elevation. The difference between rail elevations with and without the finishing machine represents the deflection due to the weight of the finishing machine. Each screed elevation should be adjusted upward by the measured deflection. Measured deflections of 0.25” or less may be ignored.

10.  Starting at the beginning of the pour, locate the finishing machine at each screed cross-section and center the paving carriage above the interior screed elevations (e.g. crown points, profile grade lines, etc.) Adjust the finishing machine crown such that the elevation of the bottom of the paving rollers equals the screed elevation at that location.

11.  Record the magnitude and direction of the crown adjustment necessary when moving the finishing machine from one screed cross-section to the next.

12.  During placement, when the vertical crown adjustment is 0.25” or less, the total crown adjustment shall be made at the midpoint between adjacent screed cross-sections. For greater total adjustments, half of the total adjustment shall be made at the first quarter point between adjacent screed cross-sections and half at the third quarter point between adjacent screed cross sections.

13.  Using the cross-slope adjustments noted for each screed cross section, move the carriage to locations above each beam/girder line and above each mid-bay. Measure and record the distance from the surface of the formwork to the paving rollers and verify concrete/rebar clearance.

14.  When the thickness or cover does not meet plan requirements, verify the following:

a)      Are screed rail elevations set properly?

b)      Are haunch depths correct?

c)      Are overhang thicknesses correct?

d)     Do crown point elevations match screed elevations?

e)      Were rail elevations adjusted for weight of machine?

f)        Are the reinforcing steel chairs set to the correct height?

g)       Is there a plan error for screed elevations?

15.  If each of the preceding items are in order, differential deflections between beams/girders in the screed cross section may be involved.

DO NOT adjust screed rail elevations.

Use CA-S-22 Dry Run Form as a template.

When a closure pour is specified, the designer assumes that the finished elevation of the existing deck is correct.  Due to conditions beyond his control or conditions he has overlooked, the finished elevation of the deck may not be as he assumed.  If this condition exists, it should be detected prior to placing the widened or second portion of the deck.  Therefore, prior to placing the widened or second portion of the deck, the Contractor should check the finished elevation of the existing portion of the deck to ensure that it is correct.  If it is determined that the finished elevation of the existing portion of the deck is not correct, the Office of Structural Engineering should be contacted for additional instructions.  


Slipform Construction of Bridge Railing (511.08)

In lieu of conventional forming, the Contractor may be permitted to slipform the parapets. This operation is accomplished with concrete that has a slump of around ±1 inch.

Prior to placing the concrete, the Contractor must take additional measures to tie the reinforcing steel in order to prevent it from dislocating during the slipforming operation. If these measures are not taken, the slipforming operation will cause the reinforcing steel to move out of its proper location.

Due to the low slump, many times the Contractor will attempt to add water to the mix as it comes down the chute from the concrete truck and enters into the hopper of the slipforming machine.  This is not allowed since it will result in concrete of inferior quality.

During the slipforming operation, small amounts of concrete will drop from the edge of the deck and onto the surface below the bridge.  If the slipforming operation takes place directly over a traveled roadway, the Contractor should furnish all necessary platforms to protect the traffic from falling concrete.  These platforms will allow access to complete the finishing operation and facilitate inspector access.

The Contractor should take steps to ensure that the finished concrete meets the specified tolerances.  These steps should include adequately tying the reinforcing steel, determining the proper slump, and properly setting up the slipforming machine.  Failure to meet the specified tolerances could result in the rejection of the parapet.

Any defects such as cracking, tearing, or honeycombing should be repaired immediately.  Occasionally, when repairing defects, the Contractor will not completely fill the defect with concrete, but will only bridge over the defect by placing the concrete on the surface of the parapet.  This is not acceptable. The Contractor should take steps to ensure that the defect is completely filled with concrete.

Normally, a small amount of hand finishing is required after the concrete has been formed.  Hand finishing can be difficult due to the low slump of the concrete.  To facilitate finishing the concrete, many times the Contractor will sprinkle water or evaporation retardant onto the surface of the concrete.  The use of these substances to aid in hand finishing is not allowed since it will only result in a surface that is subject to scaling in the future. The contractor should not broom finish the surface.

After the concrete has initially set, it is important to saw the control joints to the plan depth into the parapet as soon as possible.  Any delay in performing this operation will result in additional shrinkage cracks in the parapet.


Construction Joints (511.09)

The surface of construction joints should be even and have coarse texture such as produced by a wood float on fresh concrete.  Vibrated concrete with a closed level surface is satisfactory.  Where the construction joint terminates at an offset in the concrete surface, such as between the fascias of the deck slab and the sidewalk, the joint should be finished neatly at the corner with a wood float.

Transverse joints as permitted in 511.09, or longitudinal construction joints placed in deck slabs of steel beam or girder bridges, are constructed with keys located between the reinforcing mats and having a depth of 3/4 inch (19 mm).  If the Contractor desires a longitudinal construction joint due to an excessive slab width and because it is not provided by the plans or specifications, the request must be submitted to the Office of Structural Engineering for review.


Work Stoppage (511.10)

During the placing of a deck, unexpected difficulties may occur that halt further placing.  These may be a sudden shower, a breakdown in the concrete plant or the finishing machine, or other unforeseen interruptions.

When a shower occurs, no manipulation of concrete should be performed other than channeling the concrete that was last deposited so that water will not pond on the concrete and run back on the finished or partially finished surface.  The textured surface should be covered with the curing material as rapidly as possible.  Non-textured surfaces should be covered with polyethylene sheeting.  After the shower, all ponded water should be removed from the concrete and out through the forms before resuming placing and finishing operations.  The last surface covered with the curing material should be inspected. If it has been marred, the texture should be restored.

Investigate stoppages immediately.  If it is found that it will not allow resumption of concrete placing in sufficient time, a bulkhead must be placed immediately.  If practical, the location should not be over a pier.  The emergency bulkhead may consist of a wood strip laid across the top of the longitudinal reinforcing bars.  This strip should be as deep as the plan cover, usually 2-1/2 inches (64 mm).  Kickers can be used to secure the strip or shims inserted between the bars in order to obtain proper crown and grade.  The concrete below the wood strip should be compacted to approximately a 45 degree slope and all excess removed as far from the joint as possible and disposed of before it hardens.  After the concrete has set, but still fractures easily, the bottom edge should be broken to provide a vertical face below the bottom reinforcing steel.  This may be accomplished with a pry bar prying up from the forms. Exercise care to ensure the surface of the forms is not damaged.  See Figure 511.G - Emergency Bulkhead.

Figure 511.F – Emergency Bulkhead


Depositing and Curing Concrete During Cold Weather (511.12)

Heated concrete and protection must be provided whenever concrete is placed at an atmospheric temperature of 32 °F (0 °C) or lower or whenever weather forecasts predict temperature below 32 °F (0 °C) within the curing period.  Concrete must not be placed in contact with material having a temperature of less than 32 °F (0 °C).

The official U.S. Weather Bureau forecast for any curing period generally can be obtained from the District Office.  This information also can be obtained from some local airports and radio stations.

When the 5-day weather forecast does not predict 32 °F (0 °C) or lower temperatures at any time during the period, the Contractor should not be required to erect enclosures or to use insulated forms.  However, during the fall, winter, and spring, adequate material and equipment should be on hand to provide for unpredicted temperatures below 32 °F (0 °C).

To ensure freedom from freezing until protection can be established, the temperature of concrete should not be less than the minimum of 50 °F (10 °C) specified, but should not exceed 90 °F (32 °C) maximum.  Concrete placed at low temperatures above freezing develop higher ultimate strength and greater durability than concrete placed at higher temperatures.  Higher temperatures require more mixing water, cause slump loss, possible quick setting, and increase thermal shrinkage.  Rapid moisture loss from hot, exposed concrete surfaces may cause plastic shrinkage cracks.  It is recommended that the temperatures of fresh concrete, as placed, be kept as close to the 50 °F (10 °C) minimum temperatures as practicable.  When the air temperature is 32 °F (0 °C) or lower, it is necessary to raise the temperature of the concrete by heating the mixing water or aggregate or both.  The concrete must be protected from freezing, and specified curing temperatures must be maintained by a heated enclosure, insulated forms, or by either of these in combination with flooding.

Decks slabs less than 10 inches (254 mm) thick must be protected from freezing, and specified temperatures maintained for the curing period by a heated enclosure.

Arrangements for covering and insulating newly-placed concrete must be made in advance of placement and should be adequate to maintain the specification temperature in all parts of the concrete.

During the first few days which require protection, most of the hydration heat of the hardening cement is developed. As a result, if heat generated in the concrete is adequately conserved, outside heat generally is not required to maintain concrete at the correct temperature.  This heat may be conserved by using insulating blankets and insulated forms where repeated reuse of forms makes this practical. Outside temperatures at concrete walls, piers, abutments, or slabs above ground may be protected with insulation under various conditions (see chart to follow).  On work where protection by insulation is permitted, project personnel should check the protection proposed by the Contractor and be reasonably sure that the proposed insulation is adequate for the expected exposure before concrete placement is permitted to begin.

The application of insulation should be as follows:

1.        Blanket insulation is applied tightly against wood forms with nailing flanges extending out from the blankets so they can be stapled or battened to the sides of the framing.  Seal the ends of the blankets by removing a portion of the mat and stapling or battening the blanket to headers to exclude air and moisture.  Corners and angles are most vulnerable.  Take extreme care to ensure they are well insulated and the insulation is held firmly in place.

2.        In case of steel forms, the insulation should be applied tightly against the form and held securely with the ends sealed to exclude air and moisture.

3.        Where practicable, the insulation or insulated form should overlay any cold concrete previously placed by at least 1 foot.

4.        Any tears in the liner are to be repaired immediately with accepted waterproof material.

5.        Where tie rods extend through an insulated form, a plywood washer, approximately 3/4 × 6 × 6 inches (19 x 150 x 150 mm), should be placed on top of the insulation blanket and secured in a satisfactory manner.

6.        The tops of all pours must be covered with insulating blankets, except for areas around protruding reinforcing bars that may be insulated with straw or wrapped with insulation blankets.  Waterproof covers should be used to cover the top of such pours, as required by specifications.

7.        Protective enclosures may be constructed of canvas, plywood, polyethylene, plastic, etc. in such a manner that will maintain uniform temperatures and allow free circulation to the warmed air.

8.        For the underside of deck slabs, 3/4 inch (19 mm) plywood forms have an equivalent thickness of 0.6 inch (16 mm) and will provide protection of 32 °F (0 °C) minimum air temperature.

9.        Close packed straw under canvas may be considered a loose fill type if wind is kept out of the straw.  The insulating value of dead air space greater than about 1/2 inch (13 mm) thick does not change greatly with increasing thickness.

Heated Enclosure (511.12.A)

When salamanders or other heaters supply heat, local drying and burning of the forms may result and necessitate moving or adjustment of the setup.  Regular observance of the forms and burlap should be made to ensure that the concrete is kept wet for the duration of the curing period, as required in 511.14.  Combustion type heating units shall be vented from the enclosure to preclude damaging fresh concrete. The enclosure should surround the top, sides, and bottom of the concrete to be placed during cold weather.

Temperature Control

Thermometers for use in enclosures should be the high-low recording type and be furnished by the Contractor.  If the enclosure is long or high, more than one thermometer may be required.  The readings in the morning and the afternoon normally represent the low and high temperature respectively; carefully select the time when the high-low recording thermometers are checked.

When insulated forms are used, the thermometer must be furnished and installed by the Contractor.  They must be capable of indicating surface temperature of the concrete.  In case of a tall section, such as pier shafts or retaining walls, more than one thermometer will be required because of the temperature gradient.  Temperatures should be read twice daily for high and low readings.  When insulated forms are used, temperature of concrete will cause a lag in the temperature change of the surrounding air.  Time of observance need not be as selective for representing the high and low, but is used to indicate a trend that may require venting of the forms or erecting an enclosure.  When venting of a vertical form is necessary, it should be raised slightly at the bottom to create a chimney effect.

The temperature record must include the required temperature readings for the entire curing period.  Outside air temperatures may be local reported temperatures.

Temperature and control methods used, as well as temperature readings, must be recorded on the Inspector’s Daily Report.

Cold Weather Curing Time

To fulfill the curing requirements for concrete placed in cold weather, the surface temperature must be maintained as specified in 511.14 or be exposed to ambient air temperatures no less than 50 °F (10 °C) for 5 days.

In case any day’s temperature readings fall below the minimum specified, the duration of heating must be extended to provide the required number of days.  In case of loss or breakage of thermometers, replacements or other provisions must be made to provide a complete record.


Removal of Forms (511.13)

Falsework must not be removed until after the time-temperature requirements of 511.14 are met or satisfactory beam tests are attained.  During cold weather, forms are to be removed after the curing period in such a manner that the temperature of the concrete does not drop more than 20 °F (7 °C) in any 24-hour period.

Note 1 in Tables 511.14-1A and B states that span is defined as the horizontal distance between faces of the supporting elements when measured parallel to the primary reinforcements.  For slab deck bridges, the primary steel runs longitudinally down the deck.  For beam supported structures, the primary steel runs transversely across the deck. 

Curbs and Parapets

Forms for curbs and parapets should be observed carefully for condition of surface, flush fit of panel joints, proper installation of bevel strips, and visual and measured alignment and elevation.   Adequate form supports should be provided to ensure proper position of concrete during and after placement.  Surface rubbing does not justify the use of inferior forms or lack of adequate supports.

When expansion devices are used to allow for bridge deck expansion, more open space for expansion must be provided in the curb and parapet than is required for expansion devices.  Where conduits cross this opening, give special attention to clearance for expansion fittings to ensure free movement of the deck.

Transverse joints may be placed in the sidewalk or curb section near the center of any span.


Curing and Loading (511.14)

Curing is governed by 511.14 that requires either Method A, Water Curing or Method B, Membrane Curing.  Curing time is 7 days. No curing is required for surfaces covered by forms for the duration of the curing period.  Concrete that will be overlaid with concrete or sealed, as well as all superstructure concrete, must be cured in accordance with Method A, Water Curing.  The top surface of superstructure deck concrete must be cured for 7 days in accordance to Method A and then cured within 12 hours in accordance with Method B. Do not shorten the minimum required Method A curing time regardless of strength gain.

The curing material must be applied as soon as possible to avoid cracking of the concrete.  Application of the curing material should be applied immediately after the finishing operation is complete.

When it is necessary to work on concrete during the curing period, such as placing deck concrete adjacent to a construction joint, only the area immediately adjacent to the joint should be exposed and the remaining area protected from damage by the workers.  Plywood sheets may be used for protection.  The exposed area should be kept moistened until adjacent work is complete, after that, the cover should be restored and normal cure resumed.

Floor forms provide the cure for the underside of the slab and are not to be removed before the end of the curing period.

Method A, Water Curing (511.14.A)

When two thicknesses of burlap are used to water cure the concrete, they should be kept wet by the continuous application of water from soaker hoses or other sprinkling devices during the required period.  In lieu of continual sprinkling devices, white polyethylene sheeting or wet plastic coated blankets may be used to cover the concrete.

On bridge decks, a single layer of wet burlap is kept wet by a continuous application of water and covered by white polyethylene. The polyethylene should be placed transversely.  The edges should be lapped and held securely to maintain a moisture seal.  The curb area may be covered with a longitudinal strip that is held securely to the fascia form and laps the transverse strips.  A continuous batten may be used to seal the blanket to the form and reinforcing bars may be laid on the laps to make the seal.  Check areas suspected of having the seal broken during subsequent work or weather disturbances. If these areas are found to be drying out, soak the burlap and reseal the white polyethylene.

Plastic-coated blankets must be inspected prior to use to ensure that they are sound and will retain the moisture required to cure the concrete.  All holes and tears must be repaired so that they are watertight.  The material should be rejected if defects are numerous and repairs are questionable or if the plastic coating has cracked from aging.

Burlap and plastic-coated blankets must be thoroughly soaked with water prior to placing on the surface of the concrete.  Dry material placed on the surface of the concrete will draw moisture out. This will increase the chances of drying shrinkage cracks.  If new burlap is used, extra measures may need to be taken to ensure that it is properly soaked since it doesn’t soak up water as well as used burlap.  If burlap to be soaked is delivered to the project in a tightly wrapped condition, it should be loosened to allow the penetration of water.

Method B, Membrane Curing (511.14.B)

The concrete curing membrane is white-pigmented material meeting specifications 705.07.  The material may be either Type 1 (clear or translucent without dye) or Type-D (clear or translucent with fugitive dye).

The membrane should be applied in one or more separate coats by spraying a fine mist at a uniform application rate of one gallon per 200 square feet (70.3 square meters) of surface.  The rate of application is controlled by laying out in advance, on the surface to be cured, an area that will be properly covered by the number of gallons of compound in the spray container.  The procedure helps ensure that the membrane is applied at not less than the required rate.

Loading Requirements for QC/QA Concrete

See Table 511.14-1 in C&MS 511. Falsework may be removed from any span and all piers caps, and the concrete open to traffic when the compressive strength of sample cylinders is greater than or equal to 0.85 percent f’c or the flexural strength of sample beam is greater than or equal to 650 psi. Per Supplement 1098, the maturity curve method may be used for determining strength of the concrete. Do not shorten the minimum required Method A curing time regardless of strength gain. When placing concrete for a superstructure between October 15 and March 15, open the deck no sooner than 30 days after placement.

Loading Requirements for Non QC/QA Concrete

See Table 511.14-2 in C&MS 511. No traffic is to be permitted on a structure until the concrete has attained the age specified in 511.14.  For all spans, this is 14 days without a beam test or 7 days with satisfactory beam test. Do not shorten the minimum required Method A curing time regardless of strength gain. When placing concrete for a superstructure between October 15 and March 15, open the deck no sooner than 30 days after placement.

Loading of Completed Structure Units

No load is to be applied or work conducted that will damage new concrete.  This applies to loading or work on any part of the structure that will, in the opinion of the Engineer, cause damage.  Usually this criterion will permit work on a footing after 36 hours (or sooner) with a successful beam test, of normal curing, where bending stresses will not occur.


Surface Finish (511.15)


Shortly after the removal of forms, all cavities produced by form ties and all other holes, honeycomb spots, broken corners or edges, and other defects (except air bubble holes that may be filled by grout cleaning) must be cleaned. After being saturated with water, all cavities shall be completely filled, pointed, and trued with a mortar of the same proportions used in the concrete being finished.

On all exposed surfaces, all fins and irregular projections must be removed with a stone or power grinder, taking care to avoid contrasting surface textures.  Sufficient white cement must be substituted for the regular cement in the filling of holes and other corrective work to produce a finished surface of the same color as the surrounding concrete.

If shown on the plans, exposed surfaces that have an appearance not satisfactory to the Engineer shall be grout cleaned in a manner satisfactory to the Engineer.

The Contractor should be advised that it will be necessary to use good formwork to obtain satisfactory surfaces.

Grout Cleaning (511.15.A)

Grout cleaning shall be performed as outlined in 511.15.

Rubbed Finish (511.15.B)

When specified on the plans, rubbing shall be performed as outlined in 511.15.

Forms should be removed within 2 days after the concrete is placed.  Exceptions are the slab fascia form on which other fascia forms are set and wall forms that overlap a joint. If parapets are placed in cold weather, make provisions to remove forms and begin surface finishing on the day following placing, while maintaining a minimum temperature of 50 °F (10 °C), or postpone the placing of parapets until weather conditions are suitable for proper performance.


Roadway Finish (511.16)

Machine Finishing

A machine finish is required, except for small bridges where the Engineer may waive the requirement. Mechanized finishing machines are preferred to hand finishing methods for both consistency of surface finish and economics. The finishing machine must be self-propelled with forward and reverse drive. Mechanized finishing machines are comprised of fabricated truss sections pinned together to span the bridge deck width to be paved. The truss spans are supported at each end on a set of wheels, called “bogies,” which ride along the length of the bridge on screed rails. Suspended below the truss is a finishing head, called a “carriage,” which levels, compacts, vibrates and finishes the concrete. The machine shall have two rotating rollers, leveling augers and either a vibrating pan or vibrating rollers. See Figure 511.H. Field verify that the vibrating frequency of the pans or rollers is between 1,500 and 5,000 pulses per minute. The contractor must supply the instrument to check the frequency. The roller fins should not protrude more than 1/4 inch from the roller. Protruding fins can mechanically depress the aggregate too far from the surface of the concrete. The Contractor should detail the method used to support the machine on the deck and the complete procedure for placing the slab and submit to the Engineer for review.  Supports for the riding rails must be equipped to handle the weight of the machine in order to avoid failure or any vertical deflection.  The concrete handling, placing, and finishing procedure should be planned to ensure that the concrete will be placed and struck off with a minimum of manipulation and at a sufficient rate in order to provide workable concrete in an area adequate for proper, final hand finishing.  Success of the Contractor’s procedure on previous decks should be considered.

Screed Rail with Bogies (wheels)                     Carriage with rollers & augers


Figure 511.G – Finishing Machine    

For transverse machines, the screed should be assembled or adjusted to the required crown established from a taut line while suspended in the same manner as it will be in operation.

Prior to ordering concrete, and after the finishing machine has been made ready, make a dry run over the entire deck.  Check slab thickness and reinforcing steel cover along with crown conformance to both end dams and expansion joints.  If the rate of crown varies, and the machine can be adjusted during operation, the required crown should be determined at regular intervals not exceeding 25 feet (7.62 m), the required increment of adjustment established and the location referenced on the side of the bridge.

Plan dimensions for deck thickness, the reinforcing of steel cover which was verified during the dry run, and the witnessing of screed adjustments to the required crown must be recorded in the project records.  A last-minute check that form dimensions and reinforcement have been verified and documented should be made at this time on the Inspector’s Daily Report. Use CA-S-22 Dry Run Form as a template.

Finishing machines can be placed such that the truss sections are skewed with respect to the screed rails. This orientation allows for concrete placement parallel to the substructure skew as required by the C&MS 511. For skew angles of 15 degrees and greater, the finishing machine can be skewed to within 5 degrees of the plan specified skew angle. See Figure 511.I.

The carriage can also be skewed with respect to the truss sections. This feature allows the carriage to finish the concrete transverse to the bridge when the truss sections are placed at some other orientation (e.g., parallel to the substructure skew). In order to ensure a proper finish at transverse grade breaks (e.g., crown points), the carriage should always be oriented to finish the concrete transverse to the bridge. A special length truss section insert is required above the grade break locations such that the grade break line lies directly below opposite corners of the section. For skewed bridges without transverse grade breaks, skewing the carriage with respect to the truss sections is not required. The finishing machines can be hinged at the pin connections between truss sections in order to provide transverse grade breaks (e.g., crown points).


Paving Direction


Figure 511.H – Finishing machine oriented with skew

Although proper measurements made during the dry run should ensure plan dimensions, check measurements after the concrete is struck to grade in order to verify that the machine is still in adjustment and reinforcing steel remains in place.  Slab thickness measurements can be obtained by probing with a 1/4-inch-straight wire (6 mm) and the cover over re-steel with a 90 degree bent wire of the same size.  These measurements should be taken shortly after the start of the finishing operation, and periodically thereafter, or when an area appears questionable.  Wide, flat sections such as super elevated slopes are questionable and must be checked.  The probing should be performed in plastic concrete where it will be easier to close the void.

Some cover checks are required; however, they do not need to be as numerous as the depth checks that also reflect cover.  It is recommended that as many depth checks as possible be made as time permits.  A statement should be entered in the project records indicating that check measurements have been made and conform to plan dimensions. If localized areas do not conform to plan dimensions, they should be noted, and any corrective action documented.

During operation, a uniform head of concrete should be maintained along the full length of the screed.  Screeds should be lifted from the surface when not in use.  During operation, only the operator is permitted on the machine.  The machine should continually be in operation as long as practical and the concrete placing procedure should not exceed the speed of the machine.

Tracking or walking in the screeded surface is not tolerated.

Final Finishing                                  

It is imperative that final finishing follow immediately behind the finishing machine.  If this final finishing should fall behind, the rate of concrete placement should be reduced.

The construction joint surface under the sidewalk or the safety curb should not be used as a place for finishers to stand or as a passageway for workers.  Planks may be placed on the sidewalk reinforcement providing sufficient additional ties and braces are used if necessary to obtain a rigid framework that will not disturb the bond of the stirrups.

Minor surface irregularities left after screeding can be corrected with long handled floats.  This operation should be held to a minimum and any major irregularities encountered should be corrected by the use of a straightedge.  Use of water, evaporation retardants, or finishing agents on the surface of the concrete to facilitate finishing is not permitted.  If a Contractor adds water by continually washing his tools, require that they use a towel to dry the tools prior to reuse.


Bridge Deck Grooving (511.17)

The deck surface must be textured by using a broom to provide a surface satisfactory to the Engineer. The broom must produce a uniform, gritty texture in either the longitudinal or transverse direction.  The texturing should take place as the pour progresses after other finishing operations have been completed.  Note: If the concrete tears or “mud balls” are produced on the surface, the Contractor needs to apply less pressure to the broom or wait a few minutes until the concrete has begun to set.

After the water curing of the concrete is complete, and either before applying curing compound, or some period after applying curing compound, and before opening the bridge to traffic, longitudinal grooves, parallel to the bridge centerline, must be sawed into the surface of the deck. Apply curing compound within 12 hours after grooving the deck. The grooves must be sawed in a continuous, uniform pattern spaced at 3/4 inch minus 1/4 inch or plus 0 (19 mm minus 6mm or plus 0) and must be approximately 0.15 inch (4 mm) deep and 0.10 inch (3 mm) wide.  Grooves must be within 9 to 12 inches from devices such as scuppers or expansion joints.  On skewed bridges, in order to accommodate the equipment used to saw the grooves, the grooves must be sawed from 2 inches to 2 feet from the expansion joint.  This results in grooves with a staggered or stepped appearance. Maintain a minimum clearance of 9 inches (220 mm) to a maximum of 30 inches (750 mm) clearance between the grooves and the curb or parapet toe. However, at no point shall un-grooved portions of deck extend beyond edge line and into the temporary or permanent travelled lanes.

For staged, or phase bridge deck work, the grooves must be sawed parallel to the final, permanent bridge centerline. If the different stages or phases of the bridge deck work occur within one construction season, any stage opened to traffic shall receive an interim coarse broom finish during placement. Then the longitudinal grooves are sawed after the final stage. The interim broom finish will not be allowed as a surface texture when opened to traffic over a winter season. Longitudinal grooves must be sawed in the deck prior to opening to traffic for a winter season.

For bridge decks that widen from one end to the other, the longitudinal grooves must be sawed parallel to the centerline of the roadway. On the side of the bridge that widens, saw the longitudinal grooves to follow the edge line. Saw longitudinal grooves in the gore areas, avoiding the overlapping of grooves.


Sidewalk Finish (511.18)

Float Finish

Concrete for sidewalks, safety curbs, and tops of substructure units are struck off with a template and finished with a float to produce a sandy texture.


Sealing Joints and Cracks (511.19) 

After curing, all cracks, transverse and longitudinal joints in the deck, joints between the concrete deck and steel end dams, and joints between the concrete deck and safety curbs, barriers and parapets must be sealed with high molecular weight methacrylate (HMWM) prior to opening the deck to traffic.


Compressive Strength (511.20) 

Sample and test concrete strength according to C&MS 511.04.

Concrete Requiring QC/QA

When the bid item requires QC/QA, the Engineer will evaluate the QC compressive test sublot results according to Supplement 1127 to determine pay factors for structure concrete. 

If a single test result for compressive strength of a sublot of concrete is found to be less than 88 percent f’c, the Engineer will determine the location for evaluating the strength of the sublot represented by the low compressive strength concrete. Nondestructive testing or coring will be performed at such locations. If the reported nondestructive test results are greater than the specified f’c, the Engineer will accept the concrete and use the original cylinder results for calculating the compressive strength pay factor (PFc). If coring is performed, the core results will be used in place of the original cylinder results for pay factor determination.

If the nondestructive test results are less than the specified f’c, the concrete must be cored. The Engineer will determine the locations for the required concrete coring by the contractor for testing by the Department. The contractor must patch core holes with approved patching material. If the core results are above 88 percent f’c, the core strength results will be used for calculating the compressive strength pay factor (PFc).

If the core results indicate that the compressive strength of the concrete is below 88 percent  f’c, the Contractor must submit a plan for corrective action to the Engineer for approval. If the corrective plan is not approved, the Engineer will require the Contractor to:

1.      Remove and replace the unacceptable concrete that the sublot represents and retest the new sublot at no cost to the Department or

2.      Leave the unacceptable material in place and be paid for the sublot with a pay factor of 0.75.

If three or more sublot compressive strength acceptance test results are less than f’c, but greater than 88 percent f’c, the Engineer will require an investigation by the contractor of the reasons for the consistent low strengths. No additional placements of the concrete JMF will be made .until the investigation is completed to the satisfaction of the Engineer. The investigation should include all facets of the concrete operation including batching, mixing, delivery, clean up, sampling, testing, quality control plan, etc.  If the Engineer is unsatisfied with the results of the investigation, the JMF and the quality control plan will become not approved. The Contractor will have to develop and submit a new JMF and quality control plan conforming to the requirements of Supplement 1126, C&MS 499.03 and C&MS 511.04.  Pay factors under C&MS 511.22 for these low strength sublots will be based on the original reported cylinder strengths.

Concrete Not Requiring QC/QA

When the bid item does not require QC/QA, the Engineer will evaluate the strength results following the requirements of Table 511.22-2 and as follows:

1.      If a single compressive strength test result is less than f’c, the material will be considered unacceptable material and the Department will determine acceptance according to C&MS 106.07.

2.      If three or more compressive strength test results are less than f’c, the Contractor will be required to perform an investigation of the reasons for the consistent low strengths. No additional placements of the concrete JMF will be made until the investigation is completed to the satisfaction of the Engineer. The investigation should include all facets of the concrete operation, including batching, mixing, delivery, cleanup, sampling, testing, etc.  If the Engineer is unsatisfied with the results of the investigation, the JMF will become not approved. The Contractor will have to develop and submit a new JMF conforming to the requirements of C&MS 499.03.


Air Content (511.21) 

For concrete that requires QC/QA, test the air content of the concrete according to C&MS 455.03.  When QC/QA concrete is not required, the Department will test the air content as directed by the Engineer.

Concrete Requiring QC/QA

Any concrete with air results outside the requirements of Table 499.03-1 that is placed into the structure is unacceptable material according to C&MS 106.07.  The amount of unacceptable material will be the amount represented by the test result. The Contractor must re-evaluate the unacceptable material, at no cost to the Department, by coring the location containing the unacceptable concrete.  The Contractor must patch the core hole with approved material. If the concrete had high air content, the core must be tested for compressive strength.  Concrete with a minimum strength of f’c may be left in place. If the concrete had low air content, the core must be tested to determine the in-place hardened air content, specific surface and spacing factor according to ASTM C 457. The Contractor must remove and replace unacceptable materials with specific surface results less than 600 in-1 (25 mm-1) or spacing factor results are more than 0.008 in (0.20 mm).  The contractor must hire an independent laboratory, acceptable to the Department, to perform the testing.

Concrete Not Requiring QC/QA

Any concrete with air results outside the requirements of Table 499.03-1 that is placed into the structure is unacceptable material, according to C&MS 106.07.  The amount of unacceptable material will be the amount represented by the test result. The contractor must re-evaluate the unacceptable material, at no cost to the Department. The Department will core the location containing the unacceptable concrete. The contractor must patch the core hole with approved materials. If the concrete had high air content, the Department will test a core for compressive strength.  Concrete with a strength of f’c may be left in place. If the concrete had low air content, the Department will determine the in-place hardened air content, specific surface and spacing factor according to ASTM C 457. The contractor must remove and replace unacceptable materials with specific surface results less than 600 in-1 (25 mm-1) or spacing factor results of more than 0.008 in (0.20 mm).


Pay Factors (511.22)

Apply pay factors as follows:

Concrete Requiring QC/QA

The Department will use pay factors based on the percent within limits (PWL) to establish a final adjusted price.  The PWL will be established per lot(s) accepted in the QCP for each bid item quantity of concrete.  The Department will calculate a PWL according to Supplement 1127 using either the Contractor’s verified QC compressive test results or core results when the QC could not be verified.  The compressive strength pay factor (PFC) from Table 511.22-1 for the lot will be applied to each bid item represented in the lot.   The Department will combine approach slab and deck concrete test results in the same lot to determine final pay factors.

If the PWL value determined for the lot of concrete is below 75%, the contractor must submit a plan for corrective action to the Engineer for approval. If the corrective plan is not approved, the Contractor must remove and replace the lot of unacceptable material, at no cost to the Department, or leave the unacceptable material in place and be paid for the lot of with a pay factor of 0.75.

Concrete Not Requiring QC/QA

For concrete items that the Department performs compression testing, the Department will use a pay factor of 1.00 based on the individual compressive strength results greater than or equal to f’c for the quantity represented by the test results.  If the compressive strength results are less than f’c, that material represented by the test result is unacceptable material, according to C&MS 106.07. See Table 511.22-2.


Method of Measurement (511.23) and Basis of Payment (511.24)

The quantity of concrete for every reference number will be determined from the plan dimensions, in place, complete, and accepted with adjustments made for necessary changes or errors.  Plan dimensions shall be verified and recorded.

The final quantity for structure concrete is rounded off to the unit for the item that is listed in the proposal.  Where plan dimensions are in inches (mm), these should be converted to feet (m) and carried to a decimal place that will not affect the accuracy of the final unit.

Calculations made for necessary changes or plan errors are to be identified properly with the structure unit and reference number and to be validated by the signature or initials of the person who made the calculations and the date they were made.

The Department will calculate separate quantities of concrete due to unacceptable compressive strength per 511.20 and air content per 511.21.

The Department will initially pay the full bid price to the Contractor upon completing the work.  The Department will calculate the final adjusted payment for each item as follows:

PF1 - The final adjusted pay per cubic yard (cubic meter) or square yard (square meter), for accepted quantities of concrete:

PF1 = (Contract Bid Price) x PFC

PF2 - The final adjusted pay per cubic yard (cubic meter) or square yard (square meter) for unacceptable quantities of concrete due to compressive strength or low air content and allowed to stay in place, according to 511.20 or 511.21.

PF2 = (Contract Bid Price) x 0.75

Calculate the adjusted price per bid item by multiplying PF1 or PF2 by the appropriate quantities of concrete, then sum the values. Subtract the full bid price paid to the Contractor from the adjusted price to determine the difference. The Department will execute final adjustments by change order upon receipt of all test data.


Documentation Requirements - 511 Concrete for Structures

Contractor has to submit an accepted Concrete Job Mix Formula (JMF) 10 days before placing concrete.

For QC/QA Concrete, the Contractor has to submit a Quality Control Plan (QCP), according to the requirements in C&MS 455.02 and 455.03.

For Mass Concrete, the Contractor has to submit a Thermal Control Plan (TCP), according to the requirements in C&MS 511.04.A.

The TCP shall include:

1.      Duration and method of curing.

2.      Procedures and equipment to control concrete temperature and differentials.

3.      Temperature sensor types, locations, installation details, monitoring system, operation plan, and a remedial action plan.

4.      Criteria for form removal to control the maximum temperature differential.

The Contractor must provide and maintain a Concrete Cylinder Curing Box.

Prior to concrete placement:

1.      Engineer received advance notice from contractor placing concrete

2.      Form dimensions and elevations field verified.

3.      Forms clean and oiled.

4.      Re-steel placed according to 509.04. 

5.      Contractor has proper equipment for placement, vibration, finishing and curing.

6.      If QC/QA concrete, the Contractor has QC staff to sample and test concrete.

7.      Forms and reinforcing steel heated to minimum 32 ºF (0 ºC) prior to placing concrete             

8.      For deck, depth, and finishing machine operation documented on Dry Run Form (Use CA-S-22 as template)

9.      Place superstructure concrete when air temperature is 85 ºF (29 ºC) or less and not predicted to be above 85 ºF (29 ºC) during placement.

10.  Prepour meeting forms CA-S-4 and CA-S-6. 

During and after concrete placement:

1.       Placement and testing requirements documented on forms CA-C-1 and TE-45.

2.      Record surface temperature inside of cold weather protection.

3.      Evaporation rate as per 511.07.

4.      Concrete vibrated.

5.      On deck, document depth obtained after final screed strike-off on day of pour.

6.      Finish deck as per 511.16.

7.      Amount of curing compound used and/or method of curing per 511.14.

8.      Loading, and removing falsework as per 511.14.

9.       Document the sawing of longitudinal grooves on deck surface as per 511.17.

10.  All joints and cracks sealed per 511.19.

11.  Smoothness requirements are outlined in 451.12 and Proposal Note 555.  A profilometer will be required to check smoothness.

12.  Placement tolerances met per 511.07 or 511.08.

13.  Compressive strength of samples met requirements per 511.20.

14.  Air content requirements met per 511.21.

15.  Pay factors calculated per 511.22.