1004 - Portland Cement Concrete Mixtures

1004 - Portland Cement Concrete Mixtures

• Please see 1004 - Portland Cement Concrete Mixtures

1004 Portland Cement Concrete for Pavements

GENERAL

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MATERIALS

All materials used in MDOT’s construction and maintenance projects must be tested and/or approved before incorporation into the project. Materials are approved based upon one of four guidelines:

Basis of Acceptance	Guidelines
Acceptance	The material must be sampled, tested, and approved before incorporation into the work.
Tested Stock	A material stockpile of known quantity is sampled, tested and approved for use before shipment to the project and the supplier/distributor agrees to abide by MDOT’s program. Approved suppliers are found in the Materials Source Guide.
Certified	A material with a proven track record of meeting specifications and the supplier agrees to MDOT’s program. Approved suppliers are found in the Materials Source Guide.
Qualified Product	Proprietary materials or products previously evaluated and approved by C&T. Approved materials and products are found on the Qualified Products List in the Materials Source Guide.

Independent Assurance Testing (IAT) is done by Region materials personnel to verify that the proper procedure and equipment used in sampling and testing is within the guidelines.

Material testing for the project begins with the award of the project. At the pre-construction meeting, the Contractor must give MDOT a copy of the Testing Order listing the materials to be used and their sources.

The Materials Source Guide and the Materials Quality Assurance Procedures Manual contain guidelines and sampling procedures.

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Concrete Admixtures

Most MDOT-specified concrete will contain one or more of the following admixtures:

Air Entraining Agents - These agents are used for concrete exposed to freezing and thawing. A calibrated container, interlocked with the batching sequence and in sight of the plant operator, is required when dispensing air entraining agents.

Water Reducers - Water reducers are used in most pavement concrete to reduce the cement content and/or water-cement ratio to achieve the required minimum strength. An interlocking dispenser, similar to that used with air entraining agents, is required.

Water Reducing Retarders - Reducing retarders are seldom used except for bridge deck placement where it may be desirable to place enough concrete to allow the beams to deflect before the concrete has achieved its set. This may help reduce the likelihood of deck cracking or loss of bond between the uncured concrete and the reinforcement and/or shear developers before the concrete has achieved sufficient strength. However, retarders should not be used as a replacement for maintaining the pour sequence specified on the plans.

Non-Chloride Set Accelerators - These are used in full-depth pavement repairs to achieve early opening to traffic in moderate to warm weather. If early opening to traffic is required, every effort should be made to use as little set accelerator as necessary to achieve the required concrete strength. Current MDOT specifications require the Contractor to design the concrete mixture using the least amount of non-chloride set accelerator to achieve the minimum strength at the required opening to traffic time. The Contractor is also required to produce a trial batch and report strength results for each mix design prior to placing concrete. In general, non-chloride set accelerators are not effective toward achieving opening strengths earlier than 12 hours after concrete placement. In addition, if the average air temperature during curing is below 60 degrees, the opening to traffic strength may be further delayed. Batching and dispensing equipment at the plant, similar to that used for air entraining agents, is required.

Only MDOT approved air entraining, water reducing and water reducing retarding, non-chloride accelerating agents are permitted. The Materials Source Guide, issued by C&T, should be consulted for a list of currently approved materials and dosage rates.

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Instructions to Concrete Mix Inspector

601.01 - INSTRUCTIONS TO CONCRETE MIX INSPECTOR MATERIALS

It is the responsibility of the concrete mix inspector to ensure that the Contractor or ready mix concrete producer is supplying concrete meeting specification requirements. All concrete testers will be required to possess a Michigan Level 1 Concrete Tester Certification (three year certification). Certification and testing will be conducted at various locations statewide by the Michigan Concrete Association and the Michigan Concrete Paving Association. No other method of qualification will be allowed. To accomplish this, the inspector must:

• Read the requirements in the current edition of the National Ready Mixed Concrete Association (NRMCA) - Quality Control Manual, Plant Certification Check List. Copies of the checklist are available in the Region or TSC office.

• Verify the plant has been inspected and certified by a private inspection agency meeting the requirements of the NRMCA certification program, or has been accepted for use by the Region materials personnel as a noncertified automated plant, or approved manual plant.

• Have the proper equipment to check the concrete mixture for slump, air content and temperature.

• Check to see that truck mixers, agitators or nonagitating hauling units meet the requirements of the NRMCA.

• Cast strength specimens, as needed, for quality assurance.

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Plant Site Review

Before the concrete supplier starts to deliver concrete to the project, the inspector should check the plant site. Plants cannot adopt a standard layout because their layout depends on the site and method of materials delivery and storage. However, they can observe certain fundamental principles, especially for the handling and stockpiling of aggregate materials.

The stockpiles should be far enough apart to avoid contaminating one material with another.

While it is not a requirement, if the base for the stockpiles and roadways for the trucks are built with well-compacted granular material, it will ease the Contractor’s operations and reduce rejection of aggregates due to contamination with foreign materials.

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Contamination Sources

Trucks usually deliver aggregate materials to the plant and deposit them at the base of the stockpiles. From there, they are cast into the stockpiles by a , or a front-end loader. This introduces two possible sources of contamination with foreign material.

• If the trucks haul over muddy roads or across clay areas, the dual tires may carry large quantities of clay or mud into the stockpile area.

• If the operator becomes careless in building the stockpile and gouges the bucket into the earth under the base, contaminated material may be introduced into the stockpile. Make frequent inspections of the stockpile operations.

Materials contaminated during stockpiling or charging of the bins must be removed and changes made to the operation to prevent further contamination.

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Maintaining Moisture in Stockpiles

If blast-furnace slag coarse aggregate is being used in the concrete, the Contractor should continuously water the slag stockpile while it is being built and maintained. This is especially important during periods of hot weather and low relative humidity. If dry slag coarse aggregate is permitted to be introduced into the concrete mixture during batching, it will absorb excessive amounts of mix water, thus, increasing the potential for early-age uncontrolled random cracking of the pavement.

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NRMCA Plant Certification

Portable and stationary concrete batch plant facilities supplying Portland cement concrete (PCC) must be certified and meet NRMCA requirements. Portable concrete batch plant facilities must be recertified on an annual basis at the start of production. After each move, the Contractor must perform a verification inspection of the plant following the NRMCA plant certification checklist.

Documentation that the batch plant meets NRMCA certification requirements must be provided to the Engineer prior to batching concrete. A certified scale company must certify scales after each move.

A waiver of NRMCA certification will be permitted if it is determined that no NRMCA-certified facility is within 25 miles (40 km) of the project limits. Batching facilities meeting the requirements of a fully automated plant, and approved by Region materials personnel, will then be permitted.

If a NRMCA, or a certified or approved automated plant is not available, then a waiver of automation will be permitted and a manual plant may be used with the Engineer’s approval.

Every plant, regardless of certification or approval status, must have a current scale check report on file. The five page Concrete Plant Equipment Inspection Report, Form 580 (Figure 601-1) should be on file at the TSC (with corrections documented for any deficiencies noted) for plants receiving waiver of NRMCA certification. NRMCA certified plants must display their current Certificate of Conformance on-site, and furnish the Department with a photocopy to be on file at the TSC.

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Documentation

Concrete Tickets

The Contractor/concrete producer will have computer-generated delivery tickets from plants certified by NRMCA.

NRMCA Ticket Information
1	Name of concrete producer
2	Plant designation where batched.
3	Ticket serial number
4	Truck Number
5	Contractor name
6	MDOT job NumberDate and time the batch was loaded.
7	Grade of concrete
8	Certification executed by the producer stating that all materials have been tested and approved, or certified as meeting MDOT’s specifications. Plants dedicated to only one project are excluded from this requirement.
9	An automated printout of actual batch weights will accompany each delivery ticket.
10	Cubic Yards of Concrete
11	Delivery Date
12	Batch Loading Time
13	Maximum allowable on-site addition of water
14	Extra water added on site
15	Contractor signature or initials
16	Type and name of admixtures with amount batched

Provide a space on each ticket for the engineer to sign. Tickets need to be signed by the street or structure inspector only when, in the Engineer’s opinion, a signature is needed to document elapsed times, concrete grades or other specification requirements.

Concrete tickets for Superstructure Concrete Verify and record discharge time on tickets and sign all concrete delivery tickets. Include any testing results (air, temperature and slump) on the ticket

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Exposed Concrete

The following items may be accepted on the basis of conventional field testing (slump, air and strength) and only intermittent plant observation will be required, as deemed necessary by the Engineer:

• Curb and gutter, valley gutter and sidewalk.

• Concrete dividers, medians and glare screens.

• Culvert head walls, spillways and paved ditches.

• Nonproduction base course.

• Slope paving and headers.

• Temporary pavements and nonproduction pavement patching.

• Sign and light standard foundations.

Batch weights will be set up from an approved mix design. The concrete delivery tickets will contain the same information required for production projects, including certification that the materials used in the concrete are State tested or certified as meeting specification requirements. A NRMCA certified plant should be used the Standard Specifications for Construction using Form 580 (Figure 604-1).

Yield checks are optional, as overruns may be expected with small pours, and they may not provide correlative information.

Documentation - The individual pours may be summarized on Inspector’s Report of Concrete Placed, Form 1174A (Figure 601-6) and submitted weekly, or more frequently, as judgment dictates. The report is intended to be a source document and history which will provide information on slump, air, etc. in the event the pour should develop some deficiency. Form 1174A should have the wording “Random Plant Inspection” printed in a prominent place to indicate that a continuous plant inspection was not observed. Any pay quantities should be reported on Daily Work Report (DWR), Form 1122B (Figure 601-7).

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Nonexposed Concrete

Concrete without plant inspection and with limited field testing, as approved by the Engineer, may be used with the following concrete items:

• Manhole, catch basin and inlet foundations.

• Sign, signal and light bases.

• Fence post and guardrail anchors.

• Conduit and sewer encasement.

• Thrust blocks.

• Other nonexposed items designated in the plans or proposal such as tremie seals, mud mats or subfootings.

Substructure concrete above the subfooting and water main encasement are not to be considered in this category but must have complete reporting and inspection.

Documentation: Form 1174 will not be required, but pay quantities will be reported on Form 1174A and the Daily Work Report (DWR), Form 1122. Cylinders/beams, when made, should be reported on Concrete Cylinder/Core Compression Test Results, Form 1160B (Figure 602-2) if cylinders were cast and submitted after strength determination was completed or Report of Modulus of Rupture, Form 1160A (Figure 602-3). Concrete delivery tickets are to state the cement content per cubic yard.

DATE QUALITY CONTROL PLAN CHECK SHEET
GENERAL INFORMATION
CONTRACTOR’S NAME	PROJECT NAME
CONTROL SECTION NO.	JOB NO.
PERSONNEL QUALIFICATIONS
QC Plan Administrator
NAME	QUALIFICATION
Possession of one of the following credentials will be considered qualified: Professional Engineer (MI). National Institute for Certification of Engineering Technicians - Level III (Concrete). Concrete Technician - Level II (MCA or MCPA).
Persons Performing QC Tests
NAME	QUALIFICATION
Possession of one of the following credentials will be considered qualified: Concrete Technician - Level I or II (MCA or MCPA).
EQUIPMENT AND FACILITIES
Air Meters
SERIAL NO.	TYPE	CALIBRATION PROVIDED YES/NO
Description of curing facilities given		Acceptable? Yes / No
Description of how samples will be handled		Acceptable? Yes / No

DATE QUALITY CONTROL PLAN CHECK SHEET
Compression Testing Machine
SERIAL NO.	TYPE	CALIBRATION PROVIDED YES/NO
SAMPLING SYSTEM
The special provision for Contractor quality control lists minimal testing required.
Yield	After the start of the first concrete operation for each mix design, determine yield.	Acceptable? Yes / No
Slump	At the start of the placement, test first load (subsequent loads, if required). During concrete placement, test for slump at least once per hour.	Acceptable? Yes / No
Air Entrainment	At the start of the placement, test first load (subsequent loads, if required). During concrete placement, test for air content at least once per hour.	Acceptable? Yes / No
Temperature	At the start of placement, test first load (subsequent loads, if required). During concrete placement, test for temperature at least once per hour.	Acceptable? Yes / No
Strength	Determine the strength at least once every 200 yd3 for a specific mix design. A single strength test consists of two cylinders, or two beams.	Acceptable? Yes / No
ADMINISTRATION
Quality Control Plan
PERSON REJECTING CONCRETE
WHOM THIS PERSON WILL NOTIFY
CONTRACTOR’S REPRESENTATIVE (SIGNATURE)

Figure 601-6 - Form 1174A - Inspector's Report of Concrete Placed

Figure 601-7 - Form 1122B - Inspector's Daily Report

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Concrete Technician’s Checklist

Item	Description
1	Aggregates handled to avoid contamination in stockpiles and storage bins. Is base under stockpile?
2	Test slips or certification for all aggregates. Stockpiles must be identified in commercial plants.
3	Certification slips for cement.
4	Up-to-date materials and technology scale check and plant inspection report (should be within the past year, or since last move). Reports should be at the plant.
5	Cement scales are to be checked as requested by the Engineer using standard 50 lb. (22.68 kg) weights, or any other practical combination of weights furnished by the producer. Make sure scale knife edges are clean and centered.
6	Automatic control check performed periodically as requested by the Engineer and reported by plant inspector (Form 1114).
7	Admixture dispensers are to be checked by plant technician daily. A sufficient supply of admixture should be on hand to avoid running out of material. The air-entraining admixture, water reducing admixture or water reducing and retarding admixture dispenser must be interlocked with the batching cycle to stop. Admixtures must be on a department approved list. If non-air entrained cement is used, both a meter and visual indication of admixture must be present.
8	Check for adequate mixing time for the type of mixer used. Truck mixers are to mix at least 70 revolutions at the plant site.
9	Have updated mix design charts for materials used at the plant, and be sure that the proper mix is being used.
10	Stockpiles must be fairly uniform in moisture content. Slag stockpiles mat have to be wet down to obtain uniform moisture.
11	Select coarse aggregate unit weight and average moisture content for fine and coarse aggregate before start of production.
12	Are proper weights set on scales, presets, punch cards or computers?
13	Equipment and facilities available for water/cement ratio test on bridge decks?
14	Arrange for casting, curing and breaking of test beams.

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CONSTRUCTION

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MEASUREMENT AND PAYMENT

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701 Portland Cement Concrete for Structures

Section Under Revision

GENERAL

Concrete used in bridge construction will typically be one of three grades. Grade T is used for concrete being placed underwater, such as tremie pours. Concrete Grade S2 is typically used for all substructure concrete pours and concrete Grade D is used for bridge deck, railing, sidewalk, sleeper slab, and approach slab pours.

Sack refers to a 94 pound sack of cement. Refer to Section 601 of this Construction Manual for equipment requirements for mixing and placing concrete.

The Contractor will provide communication service from the work site to the batching plant that will always be available to the Engineer during the concreting operations.

Sections 601 and 701 of the Standard Specifications for Construction, and 12SP604(B) QUALITY CONTROL AND ACCEPTANCE OF PORTLAND CEMENT CONCRETE provide the specifications related to strength requirements, quality control, quality assurance and acceptance related to structural concrete.

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MATERIALS

Concrete materials must be accordance with subsection 701.02 of the Standard Specifications for Construction.

Materials	Specification reference
Cement	901
Fly Ash	901
Slag Cement	901
Coarse Aggregate 6A, 6AA, 17A	902
Fine Aggregate 2NS, 2SS	902
Concrete Admixtures	903
Water	911

All material must be inspected and approved before being incorporated in the work. Materials should be checked for damage in shipment or storage and to insure conformity to the required dimension, appearance and condition. Following are four main methods of material inspection acceptance:

• Material may be tested or sampled at the point of production, manufacture or supplier's storage by the Bureau of Field Services or an appointed representative. The project office should receive the resulting test report before using the material. The material should be checked for markings, such as lot number, to identify with the test report.

• Material may be certified by the supplier as meeting the specified requirements. The certification should be received in the project office before using.

• Material may be sampled at the job site. The sample is tested by Bureau of Field Services and a report is sent to the Engineer before using.

• The material may be visually inspected at the site by project personnel to insure conformance with specified requirements. Then, a visual inspection report is prepared and submitted. The required method of inspection is listed for all materials in Division 9 of the Construction Manual and is to be followed. If in doubt, the Region materials staff should be consulted.

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STOCKPILING

Aggregate

Ensure the contractor adheres to the following actions when furnishing and handling aggregate:

• Fine and Coarse - must be furnished, stocked piled and handled in such manner as to prevent segregation.

• Aggregate Secured for Stockpiles - The storage area must be firm, reasonably level, and thoroughly cleaned of all foreign materials.

• Bottom 1 foot of the Stockpile – must not be used unless a paved area is used for stockpiling.

• Frozen Aggregate Lumps – must not be used.

• Equipment – Causing contamination or degradation must not be used.

• Aggregate Moisture Content - must be kept uniform for each day's run without evidence of any surplus water.

• Slag Stockpiles or Other Highly Absorptive Aggregates - must be kept continuously wet to maintain uniform moisture content.

• MDOT Fine & Coarse Aggregates - must be stocked in separate piles or bins apart from aggregates to be used in other work.

• Coarse Aggregate (Blend of Two or More Gradations) - must be stockpiled separately for each gradation.

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Cementing Materials

Cement, slag cement and fly ash furnished to the project in bulk form must be stored in separate weatherproof bins. Wet or contaminated material may not be used.

If the Contractor changes the cement type or source, fly ash source or class or slag cement source or grade, the bin must be emptied to within the quantity used for two concrete batches before refilling with new material. Notice of the material change must be recorded on the first ticket.

The Contractor must furnish the Engineer with a shipment notice (copy) with the following information:

• The quantities of cement, slag cement or fly ash.

• A certification that the material meets MDOT requirements.

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READY-MIXED CONCRETE

Ready mixed concrete is batched and delivered as central mixed or truck mixed concrete.

Types of Concrete

Central Mixed - Completely mixed in a central mixer and transported to the delivery point in a truck agitator, a truck mixer, or in approved, non-agitating equipment.

Truck Mixed - Completely mixed in a truck mixer with an approved revolution counter, at the plant site.

Batch Mixing

Functions of Parts:

Drum or blade - Must revolve at the speed or within the speed range recommended by the manufacturer and shown on a metal plate attached to the mixer.

Mixing Time - Equals the time all cement and aggregates are in the drum until beginning of discharging the concrete. For multi-compartment mixers, the mixing time must include the transfer time between drums.

Batch Mixing Method	Minimum Mixing Time
Central Mix-Turbine	45 seconds
Central Mixed-Revolving drums & pugmills	60 seconds
Central Mixed-Revolving drums & pugmills 1 yd; (0.75 m3)	90 seconds
Truck Mixed Concrete	70 revolutions

Ingredients - Must be charged into the mixer so that some water will enter before cement and aggregate; substantially all the water must be in the drum before one third the specified mixing time has elapsed.

Ensure the mixer drum and truck mixers are completely emptied after each batch before recharging.

The maximum batch size may not exceed the mixer capacity as shown on the attached metal plate. Batch sizes for agitating units and truck mixers used to transport central mixed concrete may not exceed the manufacturer's recommendation for maximum agitating capacity.

If Volumetric Batching and Continuous Mixing methods are used, the concrete must be proportioned, mixed and discharged according to ASTM C 685.

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Elapsed Time

The time between charging the mixer and concrete discharge completion into the work must not exceed that specified in Table 601.01 of the Standard Specifications for Construction.

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Charging Time

Charging time is the time the cement contacts the mixing water or damp aggregates.

When the anticipated time between charging and discharge completion exceeds 30 minutes, the concrete must be continuously agitated.

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Adding Water

For concrete transported in truck mixers:

If additional mixing water is required to obtain the specified slump and the truck mixer is not loaded to more than its rated mixing capacity, water may be added. Water must only be added prior to any discharge.

After all water is added, a minimum of 30 revolutions at mixing speed will be required before discharging any concrete. The additional water will be added and the additional mixing completed at the work site within the maximum time specified in Table 601.01 in the Standard Specifications for Construction.

Except for fog curing, no water may be added to the concrete during discharge or placement. In particular, no water may be added to truck chutes or to pump or slip form hoppers.

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CONCRETE MIXTURE REQUIREMENTS

The Contractor is responsible for determining the concrete mixture proportions (mix design) on projects containing Quality Control (QC) provisions.

Mixes Using Fly Ash or Slag Cement

Fly ash may be used in the concrete mixture according to Table 701.01 in the Standard Specifications for Construction. A greater quantity of fly ash may be used, subject to the following requirements:

A Contractor mix design, produced by a testing laboratory, conforming to ASTM C 1077, must be submitted for the Engineer’s approval. The submittal must include documentation of the slump, air content and a 28-day compressive strength. The compressive strength in Table 701.01 in the Standard Specifications for Construction must be exceeded by at least 500 psi.

Concrete will be made and cured according to ASTM C 192, with three batches (minimum) made and tested according to the concrete grade. Any subsequent change in the mixture constituents will require that new laboratory data must be submitted for the Engineer’s approval.

Type I or IA Portland cement must be used.

The cement quantity for Type I or Type IA shown in Table 701.01 in the Standard Specifications for Construction may be reduced up to a maximum of 40 percent for fly ash or slag cement substitution.

The fly ash/slag cement weight must be equal to the weight of the cement removed.

If fly ash and slag cement are used in the same mixture, the cement quantity shown in Table 701.1 in the Standard Specifications for Construction may be reduced up to a maximum of 40 percent.

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ADMIXTURES

Air-Entrained Admixtures

Structural concrete, including concrete placed in steel shell piles require an air content of 5.0 to 8.0 percent air.

When the Contractor adjusts the amount of air entraining admixtures used, the actual amount used per sack of cement or per concrete batch will be recorded on the first delivery ticket following the adjustment.

When concrete having low air content is received at the work site in truck mixers, the Contractor may add additional air entraining admixture at the site, mixed in a small amount of water [quart (liter)], with a minimum of 30 mix revolutions until adjustments can be made at the batching plant.

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Water-Reducing Admixtures

When a water-reducing admixture is used, it must be added according to the manufacturer’s recommendations. The dosage used must not be less than the amount shown on the Qualified Products List for Admixtures for Concrete found in the Materials Source Guide. Admixture dosage rates will be based on the total cementitious material (cement plus fly ash or granulated blast furnace slag) in the concrete.

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CONSTRUCTION

Concrete Quality Control and Quality Assurance

The contractor is responsible for Quality Control (QC) of the concrete. The Department is responsible for administering Quality Assurance (QA) of the concrete. The contractor and the department will correlate testing by conducting side by side testing of the same concrete representing the first production lot to verify test results for temperature and air content of the concrete.

The QC sampling and testing must be independent from the Department’s QA sampling and testing. For QC testing, the contractor must sample and test a representative haul unit of concrete immediately after its discharge but before the pump hopper and again after the pump hopper. If the difference in air content between the two samples is greater than 2.0 percent by volume of concrete, the contractor must suspend operations and administer corrective action to determine the cause of the excessive air loss through the pump and to make the necessary adjustments to their operations in efforts to reduce the excessive air loss to less than 2.0 percent.

The engineer will conduct daily QA startup sampling and testing of temperature, slump and air content; QA sampling and testing; monitoring the contractor’s adherence to the QC plan; and inspection of field placed materials.

QA samples must be taken from the concrete as close to its final placement as practical (after the pump). In general, the sampling rate will be approximately one sample per 50 cubic yards, as determined by the engineer, with a minimum of one sampling for each day of production. The QA sampling rate and sample location will be based on cubic yard quantities. Samples will be taken from the concrete at the location as close to its final placement into the forms or on the grade as practical. If sampling from the discharge of the haul unit, the sample will be taken from approximately the middle one-third of the load.

QA sample locations will be determined as described in the ”Random Sampling for Quality Control/Quality Assurance Projects” section of the Materials Quality Assurance Procedures Manual

All concrete QC and QA must be in accordance with the requirements for non-PWL in the SPECIAL PROVISION FOR QUALITY CONTROL AND ACCEPTANCE OF PORTLAND CEMENT CONCRETE (12SP604B).

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QA Sampling and Testing

Sampling and testing must be done in accordance with the SPECIAL PROVISION FOR QUALITY CONTROL AND ACCEPTANCE OF PORTLAND CEMENT CONCRETE (12SP604B).

The following ASTM test methods apply to testing. The Department’s established procedures for sampling and testing are acceptable alternatives.

• C 31 Practice for Making and Curing Test Specimens in the Field
• C 39 Test Method for Compressive Strength of Cylindrical Concrete Specimens
• C 78 Test Method for Flexural Strength of Concrete
• C 138 Test Method for Density, Yield and Air Content of Concrete
• C 143 Test Method for Slump of Hydraulic-Cement Concrete
• C 172 Practice for Sampling Freshly Mixed Concrete
• C 173 Test Method for Air Content of Freshly Mixed Concrete (Volumetric)
• C 231 Test Method for Air Content of Freshly Mixed Concrete (Pressure)
• C 293 Test Method for Flexural Strength of Concrete

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MEASUREMENT AND PAYMENT

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