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.
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Quantities per Cubic Yard Provide Concrete with 6±2% Air
Content |
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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 |
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[2] Cementitious Content includes cement and pozzolan materials, denoted as Cm |
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[3] Strength for Mass Concrete (QC 4) may
be tested at either 28 or 56 days. |
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[4] Do not use Type III cement or accelerating admixtures
in mass concrete. |
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[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 |
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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:
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.
Type of Work |
Nominal Slump inch (mm)[1] |
Maximum Slump inch (mm)[2] |
1
to 3 (25 to 75) |
4
(100) |
|
1
to 4 (25 to 100) |
5
(125) |
|
2
to 4 (50 to 100) |
4
(100) |
|
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. |
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[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:
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).