ITEM 499  CONCRETE—GENERAL

499.01  Description

499.02  Materials

499.03  Concrete Mix Design

499.04  Adjustments and Controls

499.05 Equipment

499.06 Handling, Measuring, and Batching Materials

499.07 Batch Plant Tickets

499.08 Mixing Concrete

 

499.01  Description.  This specification consists of proportioning requirements for Portland concrete mix designs, mixing, and controls of Portland cement concrete.

 

499.02  Materials.  Furnish materials conforming to:

Portland cement............................. 701.01, 701.02, 701.04

............................. 701.05 and 701.09 or blended cement[1]

Microsilica............................................................... 701.10

Ground granulated blast furnace slag

.... (GGBFS)............................................................ 701.11

Fly ash..................................................................... 701.13

Fine aggregate [2][3].................................................. 703.02

Coarse aggregate[3].................................... 703.02, 703.13(4)

Recycled Concrete Aggregate (RCA)....... Supplement 1117

Air-entraining admixture.......................................... 705.10

Chemical admixture for concrete[5].......................... 705.12

[1] If blended cement is used, provide mill certification of all the cement and pozzolanic components and final product for approval by the Office of Materials Management

[2]          703.02 natural sand or sand manufactured from stone as specified in Item 703.02.A.3 is required in 255, 256, 451, 452, 526, and 511 deck slabs.

[3] Aggregates may be standard gradation sizes from 703.02 and Table 703.01-1 or they may be a modified gradation defined with the mix design submittal and certified by the office of Materials Management under Supplement 1069.

[4]          Applies only to 305, 451and 452 concrete.

[5]          Admixtures shall contain no more than 50 parts per million chloride ions by weight of cement except for Type C accelerating admixtures or calcium chloride for QC-FS only

 

Use water for concrete mixing free from sewage, oil, acid, strong alkalis, vegetable matter, clay, and loam.  Potable water is satisfactory for use in concrete.  Non-potable water will meet the requirements of ASTM C1602.  Water from a reclaiming system will contain no more than 0.06% chlorides.  Test the non-potable water monthly and maintain data verifying that the water meets the requirements. Provide the data at Engineer’s request.

 

499.03 Concrete Mix Designs.  Develop concrete mix designs with 1 inch maximum nominal size coarse aggregate according to ACI 301, Section 4 meeting the requirements of Table 499.03-1.; Limit the pozzolan content of any developed mix designs according to Table 499.03-2.  Conform to the requirements and procedures of this specification and  Supplement 1126 for concrete mix design submittals and approvals.

 

Only use mix designs accepted by the Department and issued a JMF number.

 

TABLE 499.03-1 CONCRETE MIX DESIGN REQUIREMENTS

 

Quantities per Cubic Yard

Provide Concrete with 6±2% Air Content

Class

Design Strength

psi (MPa)

Permeability [1]

Maximum (Coulombs)

Cementitious Content [2]

Minimum.

 lbs (kg)

Aggregate

Requirements

QC 1

4,000 (28.0) at 28 days

2,000

520 (236)

Well-Graded

QC 2

4,500 (31.0) at 28 days

1,500

520 (236)

Well-Graded

QC 3 Special

As per plan

1,500

or as per plan

520 (236)

or as per plan

Well-Graded

QC 4 Mass Concrete

As per plan [3]

2,000

or as per plan

470 (213) [4] [5]

or as per plan

Well-Graded

QC MS [7]

See Supplement 1126

N/A

800 [7] (475)

1 inch nominal maximum size

QC FS [7]

See Supplement 1126

N/A

900 [7] (534)

1 inch nominal maximum size

QC Misc [6]

4,000 (28.0) at 28 days

N/A

550[8](233)

1 inch nominal maximum size

[1]  AASHTO T277 Modified

 

[2]  Cementitious Content includes cement and pozzolan materials, denoted as Cm

 

[3] Strength for Mass Concrete (QC 4) may  be tested at either 28 or  56 days.

 

[4] Do not use Type III cement or accelerating admixtures in mass concrete.

 

[5] The maximum fly ash or GGBF slag content may be increased up to 50%.

[6] For QC Misc mixes only –Water/Cementitious ratio limited to 0.50 maximum

[7] Cement Only – No pozzolan materials

[8] Cement of cement and up to15% fly ash or up to 30% GGBF slag

 

 

Determine the permeability by testing according to AASHTO T277 except moist cure the permeability samples for 7 days at 73 °F followed by 21 days of moist curing at 100 °F.  Perform permeability testing at 28 days.

Observe the following limitations on the pozzolan materials as a percent of total cementitious content:

  

TABLE 499.03-2 POZZOLAN MATERIALS

Material

Maximum Content

(%)

Fly Ash

25

GGBF Slag

30

Micro-Silica

10

When using multiple pozzolan materials, do not exceed the individual maximum contents above for each material.  A combination of pozzolan materials may not exceed 50% of the total cementitious content by weight.

 

A. Slump.  Maintain slump within the nominal slump range in Table 499.03-3.  If below the maximum water-cementititous ratio of the Job Mix Formula (JMF), then adjust the quantity of water to meet slump requirements.  Do not use concrete with a slump greater than the maximum shown in Table 499.03-3.  When the slump exceeds the nominal slump limit of Table 499.03-3 but is below the maximum limit, the Contractor may use an occasional load of concrete in this condition, provided the mixture of succeeding loads is immediately adjusted to reduce the slump to within the nominal range.  Conduct tests on the plastic concrete for pavement at the point of placement or at an Engineer-designated location.

TABLE 499.03-3  CONCRETE SLUMP

Type of Work

Nominal Slump

inch (mm)[1]

Maximum Slump

inch (mm)[2]

Concrete pavement (305, 451, 452, 615)

1 to 3 (25 to 75)

4 (100)

Structural Concrete (511, 610, 622)

1 to 4 (25 to 100)

5 (125)

Superstructure concrete (511, 526)

2 to 4 (50 to 100)

4 (100)

Non-reinforced concrete (601, 602, 611608, 609, 622)

1 to 4 (25 to 100)

5 (125)

[1]  This nominal slump may be increased to 6 inches (150 mm), provided the increase in slump is achieved by adding a chemical admixture conforming to the requirements of 705.12, Type F or G.

[2]  This maximum slump may be increased to 7 inches (180 mm), provided the increase in slump is achieved by adding a chemical admixture conforming to the requirements of 705.12, Type F or G.

 

B. Air Content.  Ensure that the air content in all concrete at the point of placement is within the percentage range specified in Table 499.03-1

499.04 Adjustments and Controls.  Provide the following adjustments and controls during batching and placement of the concrete:

1. Batch the concrete to the proportions of the accepted JMF. Provide a workable and finishable mix.  Adjustments to the JMF’s aggregate proportions up to 100 lbs (44 kg) for workability may be made. Adjustments greater than 100 lbs (44 kg) may be made if approved by the Engineer.  Maintain an absolute volume of  27.0 cubic feet/cubic yard for the adjusted concrete mix. For Well Graded  JMF adjustments, maintain the combined aggregate gradation within the optimal zone II requirements for well-graded mixes as defined in Supplement 1126.  If outside the optimal zone II of the Coarseness Factor Chart adjust the JMF’s proportions to maintain the combined gradation  within Zone II and report the JMF changes to the Engineer. 

2. Handle, haul and store aggregates to minimize segregation, avoid contamination, and assure a uniform grading within the specified gradation.  Do not combine aggregates from different sources or of different gradings in the same stockpile.  Do not use segregated or contaminated aggregates.

3. Remove all wash water by reversing each truck drum at the plant immediately prior to reloading.

4. Adjust the SSD aggregate design weights In the JMF to compensate for the moisture contained in the aggregates and moisture the aggregates will absorb during batching.  Adjust the mix water to compensate for the aggregate moistures.

5. Do not exceed the maximum water-cementitious ratio of the JMF.

6. Use only compatible admixtures in the concrete.  Dispense all admixtures according to the manufacturer’s recommendations.  Furnish a volumetric dispenser for the Type F or G admixture or ensure that there is a gage on each truck-mounted Type F or G admixture dispensing tank.  If any admixture is added at the job site, mix the load for a minimum of 5 minutes.

7. Do not exceed the maximum water/cementitious ratio of the accepted JMF.  Use a water-reducing admixture conforming to 705.12; proportionately increase the cementitious content; or develop and submit for acceptance a new JMF.  Adjust the absolute volume of the aggregates if the cement content is increased.

8. Reject concrete loads, if during placement of any concrete, cement or microsilica balling is observed.  Revise the mixing process and/or loading sequence to prevent further balling.

9. If slump loss occurs before placement of the concrete, the concrete may be “replasticized” with an admixture to restore plasticity.  The Engineer will recheck the slump range and air content to ensure conformance to the specifications.  If after “replasticizing” the components of the load are segregated, the Department will reject the load. 

10. Completely discharge the concrete from each delivery truck within the time requirements of 499.08.

11. Provide sufficient quality control at the plant to assure conformance with this specification and project requirements.

12. Use an approved set-retarding admixture conforming to 705.12, Type B or D when the concrete temperature exceeds a nominal temperature of 75 °F (24 °C).

499.05  Equipment.  Use a Department approved batch plant and trucks.  Provide batching and mixing equipment meeting the following requirements:

A. Batching Plants.  Operate each plant so that aggregate materials are not segregated and there is no intermingling of the materials before batching.  Use weighing mechanisms that allow a visible means of checking weights and produce a printed record.  Use dispensing mechanisms for water and admixtures that allow a visible means of checking quantities and produce a printed record.

Use cement and aggregate weighing mechanisms that are accurate to within ±0.5 percent of the correct weight.  Ensure that devices for weighing or metering water are accurate to ±1.0 percent throughout the range used.

Maintain a certification from a Sealer of Weights and Measures or a scale servicing company attesting to the accuracy of the weighing and metering devices.  Have this service performed within a 12-month period before use of the plant.  A Certificate of Performance issued by the National Ready Mixed Concrete Association may be used instead of the Sealer of Weights and Measures or a scale servicing company.

Maintain the services of a scale servicing company or ten standard test weights to reach a capacity of 500 pounds (227 kg) for testing the weighing devices at the batch plant.  The Ohio Department of Agriculture will seal all device-testing weights every 3 years.

The Engineer will test weighing and dispensing devices as often as deemed necessary to ensure continued accuracy.

B. Mixers.  Provide mixers and agitators conforming to AASHTO M 157, Sections 10, 11.2, 11.5, and 11.6, except that the Department will allow mechanical counters.

For bodies of non-agitating concrete hauling equipment, provide smooth, mortar-tight, metal containers capable of discharging the concrete at a satisfactory controlled rate without segregation.  Provide covers when required by the Engineer.  The Engineer will allow trucks having dump bodies with rounded corners and no internal ribs or projections for non-agitating hauling.

499.06  Handling, Measuring, and Batching Materials.  Do not stockpile aggregates from different sources or different gradations together.  The Engineer may direct reworking or cleaning, or may reject aggregates that have become segregated or mixed with earth or foreign material. 

Prior to and during batching, maintain all coarse aggregates at a uniform moisture content.

For all slag aggregates or other aggregates with a reported absorption above 3.0 percent, only use aggregates with moisture contents at or above the ODOT-reported SSD for that aggregate as follows:

1.       Use appropriate stockpile watering systems capable of raising and maintaining aggregate moisture at or above SSD.  Test the moisture content of the watered aggregate stockpiles at least five (5) locations to assure the stockpile is at or above SSD

2.       Have processes to maintain the aggregate stockpile at SSD until stockpile draining for SSD consistency has begun. Twenty-four (24) hours before batching concrete with the aggregate, shut down the stockpile watering process to allow drainage and to establish a uniform moisture content.  

3.       Run moisture content tests at least twice a day during concrete production.  If the moisture content varies between tests by more than 1% increase the moisture testing frequency to assure correct batching information. 

4.       Provide the moisture content test results as part of all quality control plant ticket information.    

Separately weigh the amounts of fine aggregate and coarse aggregate, as determined by the Engineer and outlined in 499.03.  Use a separate weighing device for cementitious materials.

Conduct batching such that the weight of cement is within a tolerance of ±1.0 of the weight required and the weight of each aggregate batched is within ±2.0 percent of the weight required.  Measure water by weight or volume to within a tolerance of ±1.0 percent of the required amount.  Dispense admixtures to within a tolerance of ±3.0 percent of the required amount.

The Engineer will approve methods and equipment used to add admixtures into the batch.  Add air-entraining admixture at the time of batching.

499.07  Batch Plant Tickets.  Furnish a concrete batch plant ticket to the Engineer for each load of concrete delivered for use on the project.  Use computer generated batch tickets.  At a minimum, include the information listed in Table 499.07-1 on each ticket:

TABLE 499.07-1  EVERY BATCH TICKET

Name of ready-mix batch plant

 

Batch plant No.

 

Batch plant location

 

Serial number of ticket

 

Date

 

Truck number

 

Class of concrete

 

JMF Number

 

Batch time

 

Batch size

yd3 (m3)

Actual weights of cementitious material:

 

   Cement

lb (kg)

   Fly ash

lb (kg)

   Ground granulated blast furnace slag

lb (kg)

   Microsilica

lb (kg)

   Other

lb (kg)

Actual weights of aggregates:

 

   Coarse

lb (kg)

   Intermediate

lb (kg)

   Fine

lb (kg)

   Other

lb (kg)

Actual weight of water

lb (kg)

Actual volume of admixtures:

 

   Air-entrainer

fl oz (mL)

   Superplasticizer

fl oz (mL)

   Water-reducer

fl oz (mL)

   Retarder

fl oz (mL)

   Other

fl oz (mL)

Aggregate moisture contents:

 

   Coarse aggregate

%

   Intermediate aggregate

%

   Fine aggregate

%

Water-cementitious ratio, leaving the plant

 

 

Provide the information in Table 499.07-2 with batch tickets for each day’s first load of concrete and for each JMF.  Include Table 499.07-2 information on the batch ticket or furnish the information on a separate computer-generated or handwritten form attached to the batch ticket.

If during the concrete manufacturing process any of the information listed in Table 499.07-2 changes, resubmit Table 499.07-2 information with the first batch ticket supplied with the changed concrete.

TABLE 499.07-2  FIRST TICKET EACH DAY, EACH JMF

Cementitious Materials:

Source:

Grade or Type:

Cement

 

 

Fly ash

 

 

GGBF slag

 

 

Microsilica

 

 

Other

 

 

Admixtures

Brand:

Type:

Air-entrainer

 

 

Retarder

 

 

Superplasticizer

 

 

Water-reducer

 

 

Other

 

 

 

The provided concrete batch ticket information is according to ASTM C 94/C 94M, Section 13.

The Engineer may require supporting data to validate the basis for furnished aggregate moisture contents.

Include the cost for generating and supplying the information of this section and the concrete batch tickets in the individual concrete items.

499.08  Mixing Concrete.  Use a central mix plant or in truck mixers to mix the concrete.

When using a central mix plant, mix the concrete not less than 60 seconds   Begin the mixing time when all materials are in the drum and end the mixing time when discharge begins.  Include transfer time in multiple drum mixers in the mixing time.  Remove the contents of an individual mixer drum before a succeeding batch is emptied into the drum.

When concrete is mixed using a truck mixer for complete mixing, mix each batch of concrete at the rotation rate designated on the mixer as mixing speed for not less than 70 revolutions of the drum.  Transport mixed concrete from the central mixers in truck mixers, truck agitators, or trucks having non-agitating bodies.  Within 60 minutes after cement and water are combined, deliver and completely discharge concrete.  If an approved set-retarding (705.12, Type B) or water-reducing and set-retarding (705.12, Type D or G) admixture is used at no expense to the Department, complete discharge within 90 minutes after combining the water and the cement.

When concrete is delivered in transit mixers and before discharging any of a batch, the Engineer may allow adding water within the specified water-cement ratio limits.  Perform sufficient mixing, a minimum of 30 revolutions at mixing speed, to adjust the slump and to regenerate the specified air content throughout the batch.  Adding water will not extend the above 60 and 90-minute time limitations.

When approved by the Engineer, the Contractor may use approved admixtures (705.12, Type F or G) for retempering the load to adjust the slump after the start of discharge.  Mix for a minimum of 30 revolutions at mixing speed after addition of the admixture.

Use admixtures containing no more than 50 parts per million chloride by weight of cement only when specified in the Contract Documents, the accepted JMF, or with the Engineer’s written permission.

The procedure to make and test concrete beams for the modulus of rupture is Supplement 1023.

Until discharged in the work, ensure that the temperature of all concrete does not exceed 95 °F (35 °C).