ITEM 455 Quality Control PLAN, TESTING AND ASSURANCE for QC/QA Concrete
455.02 Quality Control Plan Basic Requirements
455.03 Additional Quality Control Plan Requirements for Structures
455.04 Additional Quality Control Plan Requirements for Concrete Pavement
455.05 Department Quality Assurance
455.06 QCP Submittal and Corrective Action
455.07 Basis of Payment
455.01 General. Use this specification for items 451, 452, 305 and 511 when the bid item description requires QC/QA. This specification defines the minimum Quality Control Plan (QCP) requirements, the Contractor’s minimum quality control (QC) materials testing and the Department’s quality assurance (QA) materials verification testing requirements.
Develop a QCP to assure that all materials and construction practices for the item will conform to the specifications. Establish the responsibilities, duties and frequency for both in-process controls and quality control testing at the concrete’s source and at the job site.
455.02 Quality Control Plan Basic Requirements. Submit a complete QCP that includes, at a minimum, the following:
A. Basic Information. Provide the following information:
1. The name and location of the Department inspected and approved concrete producer.
2. The Department accepted Job Mix Formula (JMF) to be used for each item.
3. The name and accreditation of the AMRL Accredited Laboratory to be used for testing the strength samples for structures or pavements.
4. Name of the person(s) who is responsible for compliance with the QCP; acting as liaison to the Department; reporting any non-specification test results and assuring that adjustments are made to remedy problems.
5. Names of all technicians who will perform plant or field site inspection, sampling and testing. Use ACI Grade I certified technicians to perform concrete sampling and testing. Provide copies of their ACI certificates.
6. Calibration records of test equipment to be used on the project.
7. Develop and provide example forms for reporting QC test results to the Engineer conforming to 455.03.C or 455.04.G.
B. Minimum Quality Control at the Concrete Source. Address how the following items will be controlled in the QCP:
1. Verify that the material sources are certified for the type of work in which they are to be used.
2. Verify that aggregates, cementitious materials and admixtures sources and design weights match the proposed JMF.
3. Describe how aggregates will be hauled, stockpiled and handled to minimize segregation, avoid contamination, and assure a uniform gradation.
4. Describe procedures and frequency used to control and measure aggregate moistures.
5. Provide the batching sequence and mixing procedures to be used to assure that material balling does not occur.
6. Describe how adjustments to the SSD aggregate design weights in the JMF are made to compensate for moisture contained in the aggregates during batching.
7. Describe how adjustments to mix water will be made to compensate for aggregate moistures to assure the JMF’s water-cementitious ratio (W/Cm) is not exceeded.
8. Define how the batching tolerances of 499.06 are assured.
9. Provide the information reported on the batch ticket and how it will be validated that it meets the requirements of 499.07.
10. Describe the method and frequency of assuring that the combined aggregate gradation remains within Zone II of the Coarseness Factor Chart. If adjustments are made to the JMF proportions, provide the individual aggregate gradations, combined aggregate gradation, and verification that the proportions remain within Zone II of the Coarseness Factor Chart to the Engineer prior to placement.
11. If using a non-potable water source, describe the procedures and frequency to verify that the water meets the requirements of ASTM C1602.
a. If a reclaiming system is used, describe the method and frequency of testing to ensure that the water contains no more than 0.06% chlorides.
12. Describe how and when the water is removed from the mixer prior to batching a new load of concrete.
13. Describe methods to verify that the storage and dispensing methods for the admixtures comply with the manufacturer’s recommendations.
14. Describe methods to keep the concrete temperature within specifications and how to mitigate effects of changes to the set time.
15. Define the desired slump and tolerance for concrete in each construction item.
16. Define the acceptable yield range, testing frequency to verify that the concrete is maintained within the range.
455.03 Additional Quality Control Plan Requirements for Structures. In addition to basic QCP minimum requirements of 455.02, provide the following for structures:
A. Material Quality Control Requirements. Provide the following controls for the concrete materials:
1. Divide the concrete for the project into lots and sublots and define the placement sequence for each work item as follows:
a. Division of Lots. A lot consists of concrete in a structure of the same class of concrete. Generally this is divided into substructure and superstructure items. Include approach slab concrete with the superstructure lot. Combine structural components requiring the same class of concrete with different reference numbers into a single lot. However, one exception is a slipformed parapet may be considered separately from a bridge deck of same class of concrete.
b. Division into QC Sublots. Divide each lot into sublots of not more than 50 yd3 (40 m3) for obtaining QC samples. In no case should there be less than 3 sublots in a lot. The Engineer will approve the sublot division.
2. Determine and define the sampling location depending on placement method (i.e. pumping, tremie, direct chute deliver, etc.) and the manpower to be utilized to perform the testing.
a. Define in the QCP plan equipment and methods to be used for 455.03.A.3.b.
3. Perform at least the following Quality Control Testing for Air content and Slump as follows:
Air Content. Sample the concrete to perform the QC air testing at the point of discharge. Use the following quality control procedures during placement:
a. Sample and test the air content on at least the first three (3) loads of concrete delivered for each day’s placement. Ensure the air content is within the specified parameters in Table 499.03-1. If the air content is stabilized to the Engineer’s satisfaction, extend the testing frequency to each sublot.
b. For concrete delivered to the point of placement by means of pumping equipment, provide a hose at the end of the line that is at least 0.5 inch (12 mm) smaller in diameter than the line on the boom to provide back-pressure in the system in order to minimize the amount of air loss in the concrete. If proposing an alternate method to produce the back-pressure and minimize the air loss, describe the proposed method in the quality control plan.
During the first three loads, sample the concrete at the point of discharge and the point of placement and test to verify that the loss of air going through the pump does not exceed 1%. Obtain concrete samples at the point of placement without interrupting the continuous flow of concrete by either passing the pump line over a sampling container or obtain a composite sample from five different portions of the deposited concrete prior to vibration.
Make adjustments to the pump setup when the air loss is more than 1%. If successful in controlling the air loss below 1%, the required minimum air content for the concrete at point of discharge will be increased by air loss over the requirements of Table 499.03-1.
c. If an acceptable air loss cannot be achieved, sample the air at the point of placement on every load tested.
When concrete cannot feasibly be sampled at the point of placement, at the Engineer’s direction, provide a trial placement of concrete with pumping equipment at the most severe condition (e.g. the pump line boomed straight up and down), using the proposed method to verify that the method has acceptable air loss.
If a load of concrete is tested and found to have an air content beyond the limits of Table 499.03-1, do not accept and place that load unless it can be adjusted to be within the specified limits. Do not adjust the air content using a defoaming agent.
i. Notify the Engineer and test at least the next three loads for air to ensure that the air content is again stabilized to the Engineers satisfaction. The sampling frequency may then be extended back to one test for every sublot.
4. Establish who is responsible for reporting air and slump results to the Engineer within 1 day after each placement.
5. Describe the methods for initial curing, transporting, curing, testing and reporting test results of the QC compressive strength specimens to the Engineer within five(5) days or the completion of testing.
a. Define the unique sample identification and tracking method of concrete specimens.
6. QC Compressive Strength Testing. Perform QC sampling for compressive strength for each sublot from the load randomly determined by the Engineer. Sample the concrete at the point of discharge unless the concrete’s air content is being sampled at point of placement.
For each sublot make one (1) set of three (3) – 4 x 8 inch (100 x 200 mm) QC compressive strength cylinders. Perform all required curing, transporting, capping and testing of the samples to conform to the applicable ASTM specifications.
Have the AMRL laboratory perform the compression testing on the cylinders.
7. Field Cured Strengths. Determine whether field cured cylinders, beams or maturity curve acceptance will be used for 511.13 and 511.14 strength testing. Define how many cylinders or beams will be made per placement.
If developing a maturity curve, provide the maturity curve to the Engineer with the QCP.
a. Field Cured Samples. Describe the methods for transporting, testing and reporting the test results of field cured samples for falsework removal and opening to traffic or propose in the QCP maturity testing and provide the maturity curves for the concrete conforming to Supplement 1098.
b. Define the reporting methods to be used to keep the Engineer informed that field cured strength results conform to the requirements for construction, falsework removal and opening to traffic.
B. Construction Process Quality Control Requirements. In addition to the requirements of 455.02, Provide the following for the construction processes:
1. Establish and define in the QCP the minimum required rate of concrete delivery for continuous placement for each construction item; determine if the plant capacity is capable of providing the concrete at the established rate; and determine how many trucks will be used to provide the concrete at the specified rate of delivery.
2. Describe the procedures and equipment to be used for delivering and placing concrete for each item; methods of consolidating, finishing and grooving the concrete; and methods of curing the concrete.
3. Describe methods and frequency of assuring the grade, super elevation, slab thickness, reinforcing steel cover, etc. meets the plan dimensions.
4. Establish the orientation of the finishing machine on a skewed superstructure to conform to 511.07.
5. Describe the methods to be used to meet cold or hot weather procedures as necessary.
6. Describe methods to prevent the evaporation rate from exceeding the specification requirements and actions to be taken when ambient and concrete temperatures exceed the requirements of 511.07.
7. Describe the methods of protecting concrete if inclement weather occurs.
8. Describe how and when the vibrator frequency is verified to conform to 511.07.
9. Describe the placement procedures to be used to assure that the tolerances for slipformed concrete meets the requirements of 511.08.
10. Describe the methods and schedule for providing control joints in parapets according to 511.08.
11. Describe the lighting plan equipment and methods, when necessary for placement according to 511.07.
C. Reporting. For the Laboratory tested QC air content results report the following information within one day of completing the testing. For the Laboratory tested QC compressive strength results report the following information within five(5) days of completing the testing:
1. Sample ID, as provided by the Department *
2. Project number
3. Producer name
4. Class of concrete
5. Batch Ticket number
6. Date sampled
7. Lot and Sublot identification
8. Placement and sample location
9. Air content
11. Concrete Temperature
12. Batch Weight *
13. Unit Weight *
14. Specimen Size *
15. Date Tested *
16. Age *
17. Individual strength results and average strength *
18. Type of fracture *
19. Laboratory name
20. Technician name
* Not required when reporting air content test results.
455.04 Additional Quality Control Plan Requirements for Concrete Pavement. In addition to the requirements of 455.02, provide the following information:
A. Division of Pavement into Lots. For the purpose of thickness and strength determination, a lot consists of the entire pavement area of the same pavement thickness and the same class of concrete. Areas using high-early strength concrete are considered a separate lot. In the QCP define the lots for the project. The Engineer will approve the lot division.
B. Division of Lots into Quality Control Sublots. Provide the placement sequence and placement widths for the pavement work and determine the sublot division conforming to Supplement 1064. Provide the Engineer the proposed sublots. The Engineer will approve the sublot division.
C. Material Control Requirements. During production of the concrete pavement, perform the following quality checks:
1. Check the aggregate stockpile conditions, gradation and moisture condition daily.
a. Provide the name and OAIMA Level II certification of the person(s) performing the aggregate gradation.
b. Define the methods of reporting results to the Engineer including whether the concrete aggregate proportions still conform to the mix’s well graded requirements.
2. For portable plants, assure that the plant is inspected by the Department prior to placing concrete. Describe the procedures and frequencies to verify the mixer blades condition and the scale, gage, meter and admixture dispenser operation.
3. During paving, perform the following:
a. Yield. Define the tolerance and determine the frequency for testing the yield. At a minimum, test the first day of paving, then every fifth day of placement thereafter.
b. Air, Slump and Temperature. Sample and test the concrete at least each ½ day of operation at the placement location.
4. Testing for opening the pavement to traffic early according to 451.18. Describe the methods to be used to assure the modulus of rupture obtains 600 psi (4.2 MPa). Define the methods to report results to the Engineer.
D. Pavement Cores for Compression and Thickness. Define at what age the sublot cores for strength and thickness will be taken. Define the age the cores will be tested for compressive strength. Take strength cores at the same location as the cores for thickness determination. Determine sublot core locations according to Supplement 1064.
1. Pavement Thickness Measurement. Define who will be measuring the pavement thickness according to Supplement 1064. Define the frequency of reporting pavement thickness results to the Engineer. When the sublot core’s thickness is deficient, follow the requirements of 451.18 for additional core locations to determine the deficiency’s limits.
2. Define how the Engineer will be provided access to witness the measurements.
3. Define the method and frequency of reporting pavement thickness results to the Engineer
E. Concrete Strength. For each sublot, test the core strengths using an AMRL accredited laboratory.
1. Propose the method and frequency of reporting the results to the Engineer for acceptance.
F. Construction Process Requirements
1. Define the minimum required rate of concrete delivery for continuous placement and assure that the equipment and transportation is adequate to provide the concrete at that rate.
2. Describe the methods of protecting the concrete in the case of inclement weather.
3. Describe the methods and frequency of controlling and checking the plastic thickness during paving and reporting issues to the Engineer.
4. Define fine grading methods and equipment
5. Define the procedure and frequency of conditioning the subbase or subgrade before pavement placement.
6. Define who will perform the HIPERPAV analysis required in 451.09 and the proposed timeframe the Engineer will have to review the report.
7. Describe equipment and methods for consistently delivering and evenly spreading the concrete in front of the paver.
8. Describe the procedure for dowel bar or load transfer device installation and methods for determining proper placement location after concrete placement. Assure methods conform with 451.09.B.
9. Describe methods of monitoring the vibrator operation and frequency, time of day, station location and track speed according to 451.05.B
10. Define materials, methods and controls for curing and joint sealing and assuring application requirements.
11. Describe joint sawing methods and proposed timing to the sawing operation.
12. Describe finishing and pavement grooving methods.
13. Pavement Smoothness.
a. Define methods to check pavement smoothness conforming to 451.13 and reporting to the Engineer
b. If other smoothness tolerances are required in the contract define the methods to measure, evaluate, and report the results to the Engineer
1. Report the following QC testing information to the Engineer daily.
a. Project number
b. Class of concrete
c. JMF number
d. Batch Ticket number
e. Date and Time sampled
f. Air content
h. Concrete Temperature
i. Aggregate moistures results
j. Aggregate gradation results
k. Laboratory name
l. Technician name
2.Report the pavement thickness measurements conforming to the form in Supplement 1064.
3. Report the compressive strength test results from the QC cores sampled according to 451.18.B with the following information:
a. Pavement lot
b. Class of concrete
c. JMF number
d. Sublot number
e. Core Location
f. Placement date
g. Age at time of testing, in days
h. Compressive strength.
i.Name of Concrete Producer
j. Name of Contractor
k. Name of Laboratory
455.05 Department Quality Assurance. The Department will perform Quality Assurance sampling and testing as specified or as deemed necessary.
A. Structure Concrete. The Engineer will perform will determine random number locations for QC compressive strength testing of each sublot.
1. Random Number Determination. The Engineer will determine a random number for each sublot to determine from which load the QC sample will be taken using the table in Supplement 1127 or a random number generator.
The Engineer will perform side-by-side sampling and testing with the contractor and for slump air and compressive strength and compare results.
1. Slump and Air. The Engineer will perform side-by-side air and slump field testing with the Contractor and compare results. If the difference between the Department’s and the Contractor’s test result is greater than the tolerances listed below, the Contractor and Engineer will determine the reason for slump or air content differences and make necessary adjustments. The Engineer may stop the placement until the reason for the difference is established and corrected. The Engineer will check one of the first three loads delivered. Once the results are within the tolerances listed below, the Engineer may reduce the QA sampling and testing frequency to 10% of the Contractor’s subsequent QC tests.
Slump ±1 inch (25 mm)
Air Content ±1%.
2. Compressive Strength. The Engineer will obtain compressive strength QA samples from the same location as the Contractor’s quality control samples at a frequency of one QA sample for every 10 sublots, or at least one per lot. The Engineer will make six (6) 4 x 8 inch (100 x 200 mm) cylinders for each sample. The Engineer will mark the cylinders with identification and the Contractor shall provide initial curing at the project.
After the initial curing at the project site, deliver three (3) QA cylinders to the Department’s Laboratory and three (3) QA cylinders to the AMRL accredited laboratory for standard curing and testing. The Accredited Laboratory will test the QA sample and the QC sample and report the test results on the form accepted by the QCP. Distinguish the QA from the QC results for the sublot.
The Engineer will compare and verify that the Department tested QA, Contractor tested QA and the matching QC test results are within 14% of the Departments QA result. If the comparison is favorable, the Contractor QC testing is considered verified.
a. When the comparison of the results are more than 14%, investigate the results with the Engineer to determine the reason for the difference. If the reason for the difference cannot be determined to the Engineer’s satisfaction, the Engineer will require the Contractor to either non-destructively test or core the concrete represented by the cylinder tests to determine compressive strength. Hire an independent laboratory to perform this additional testing. The Engineer will witness the testing and evaluate the results. The Department will reimburse the Contractor for all testing costs when the Department’s results are in error. If the QC results are found to be valid, use the QC results. If the QC results are not valid, use the core results to determine the compressive strength values for pay factors, 511.22.
B. Pavement and Base Concrete. The Engineer will perform side-by-side sampling and testing with the Contractor and compare results.
1. Air Content. The Department will perform side-by-side quality assurance testing of the air content on at least 10 percent of the Contractor’s QC samples. The results will be compared and if the difference between the Department’s and the Contractor’s test results is greater than ±1% the Contractor and Engineer will determine the reason for difference and make necessary adjustments. The Engineer may stop the placement until the reason for the difference is established and corrected. Make any required modifications or changes to the QCP, the technician, and equipment before continuing paving.
2. Compressive Strength. The Engineer will randomly select 1 out of every 10 QC core locations to have an additional core obtained as a QA strength sample according to Supplement 1127. The QA core sample will be provided to the Engineer and the Department will cure and test, the QA core at the date specified by the Contractor.
The Engineer will compare and verify that the Department tested QA core and the matching Contractor tested QC core test result are within 13% of the Departments QA result. If the comparison is favorable, the Contractor QC testing is considered verified.
If the difference between core results is greater than 13%, the Engineer will investigate both the Contractor’s laboratory and the Department’s laboratory for the accuracy of the equipment and procedures for conducting the compressive strength testing of the cores. If the investigation does not determine the reason for the discrepancy between cores, the Contractor will re-core the sublot in dispute and the core will be tested in the Department’s Central Laboratory. The Central laboratory core result will be compared to the Contractor’s QC core result. If the comparison is within 13%, the Contractor’s QC result will be accepted and considered verified. If not within the 13% range, the project sublots will be re-cored by the Contractor and tested by the Department. The results will be used for payment under 451.19.B.
455.06 QCP Submittal and Corrective Action. Submit the proposed QCP to the Engineer for acceptance at least 10 days prior to placing concrete.
If the submitted QCP is not accepted by the Engineer, revise and resubmit the QCP and provide an additional 10 days for acceptance. Reschedule the concrete placement, when necessary, to allow time for the review and acceptance of QCP.
The QCP acceptance is based on the concept that the proposed QCP procedures will provide work meeting all specification requirements. If the accepted QCP is not being followed the Engineer will require compliance or re submittal of any modifications for review and acceptance.
When the actual work produced by the QCP does conform to specification requirements, the Engineer will require modification of the QCP to return the work to conformance. When notified by the Engineer propose modifications to the QCP for acceptance. Do not continue work until the Engineer has either accepted the revised QCP or determined work can continue.
455.07 Basis of Payment. The cost of developing and implementing the QCP is incidental to the cost of the concrete sold with the QC/QA requirement.