10-15 Section 1002. Contractor Quality Control for Concrete
1002.01. Description This work consists of providing and maintaining an effective concrete QC plan for all concrete production and placement on the project. The Engineer will not sample or test for QC or assist in controlling the Contractor ’s production operations. 1002.02. Materials None specified. 1002.03. General Requirements.
A.Standard Reference Procedures. The following ASTM test methods apply to the Department ’s established procedures for sampling and testing:
1.ASTM C31/C31M – Standard Practice for Making and Curing Concrete Test Specimens in the Field
2.ASTM C39/C39M – Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
3.ASTM C78/C78M – Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)
4.ASTM C138/C138M – Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
5.ASTM C143/C143M – Standard Test Method for Slump of Hydraulic -Cement Concrete
6.ASTM C172/C172M – Standard Practice for Sampling Freshly Mixed Concrete
7.ASTM C173/C173M – Standard Test Method for Air Content of Freshly Mixed Concrete by the Volumetric Method
8.ASTM C231/C231M – Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
9.ASTM C293/C293M – Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Center -Point Loading)
10.ASTM C1064/C1064M – Standard Test Method for Temperature of Freshly Mixed Hydraulic-Cement Concrete
B.Quality Control Elements . Prepare, implement, and maintain a QC plan for concrete, specific to the project, that will provide quality oversight for MDOT Standard Specifications for Construction Section 1002
10-16 production, testing, and control of constructi on processes . The QC plan
must be in conformance with the contract and must identify all procedures used to control production and placement including when to initiate corrective action to maintain the quality and uniformity of the work. Submit the QC plan to the Engineer for review a minimum of 14 days before the start of related work . The Engineer will notify the Contractor of any objections relative to the content of the QC plan within 7 days of receipt of the QC plan. Do not begin concrete placement bef ore approval of the QC plan by the Engineer . If the approved QC plan fails to provide acceptable work, or acceptable control of the work, the Engineer may require the Contractor to revise the QC plan . Revisions to the QC plan must be approved by the Engine er prior to resuming work. If the local average minimum temperature is forecast to be below 40°F for 10 consecutive days, submit a revised QC plan, for the Engineer ’s approval, addressing in detail changes in materials, concrete batching and mixing process es, construction methods, curing, and protection of the in situ concrete to ensure that the necessary quality characteristics of the hardened concrete product will not be compromised as a result of the cold weather . The revised QC plan must be approved by the Engineer prior to cold weather concrete placement . Do not remove supplementary cementitious material from the concrete mixture. Project -specific items required in the QC plan include, but are not limited to, the following:
1.Organization al chart;
2.QC Admi nistrator and contact information;
3.The name(s), credentials, and contact information of the on- site QC staff responsible for QC testing and QC plan enforcement;
4.Methods for interaction between production and QC personnel to implement timely corrective acti on including suspension of work;
5.Coordination of activities;
6.Documentation, procedures, and submittals;
7.Project and plant specifics;
8.Certifications for concrete production facilities;
9.Current testing equipment calibration documentation, including calibrati on factor;
10.Sampling, testing, and initial curing facilities for QC and quality assurance ( QA) strength test specimens; MDOT Standard Specifications for Construction Section 1002
10-17 11. Stockpile management plan;
12.Corrective action plan;
13.Mixing time and transportation, including time from batching to completion of deliver y and batch placement rate (batches per hour), along with the manufacturer ’s documentation relative to the batching equipment ’s capabilities in maximum mixing capacity and minimum mixing time;
14.Placement and consolidation methods including monitoring of vibration, depth checks, and verification of pavement dowel bar alignment;
15.Process for monitoring stability of air content of fresh concrete during concrete production and placement;
16.Hot and cold weather protection considerations and methods;
17.Control charts with action and suspension limits;
18.Verification for non- deleterious alkali -silica reactivity (ASR), as specified in the contract;
19.Mix design, JMFs, and supporting documentation;
20.Proposed production lot size and location for use of each JMF on the project;
21.Frequency of sampling, testing, and yield verification;
22.Handling, protection, initial curing, and transporting of strength test specimens;
23.Methods to monitor construction equipment loading and open-to -traffic strengths;
24.Finishing and curing procedure;
25.Ride QC; and
26.List of QC records to be submitted to the Engineer in accordance with subsection 100 2.03.C.
C.QC Records . Maintain complete records of all QC tests and inspections . Document the action that was taken to correct deficiencies . Include sufficient information to allow the test results to be correlated with the items of work represented. Furnish one copy of all QC records, including test reports, to the Engineer within 24 hours after the date covered by the records in a format acceptable to the Engineer. MDOT Standard Specifications for Construction Section 1002
10-18 If the Engineer is performing QA sampling and testing at the same time
the Contractor is performing QC sampling and testing, all associated QC records must include the appropriate production lot identification number that correlates with the Department ’s QA production lot identification number.
D.Personnel Requirements . Individuals performing QC tests must demonstrate that they are proficient and capable of sampling and testing concrete or aggregate in accordance with the associated test procedures and Department requirements prior to the beginning of related work . Any JMF adjustments must be made by a Michigan Concrete Association (MCA) certified Michigan Concrete Technician Level II. The QC Administrator must have full authority and responsibility to take all actions necessary for the successful implementation of the QC plan, including but not limited to, the following:
1.Monitoring and using QC tests, control charts, and other QC practices to ensure that delivered material s and proportioning meet specification requirements;
2.Monitoring materials shipped to the project, prior to their use, to ensure their continued compatibility toward producing consistent quality;
3.Periodically inspecting all equipment utilized in transporting, proportioning, mixing, placing, consolidating, finishing, and curing to ensure proper operation;
4.Monitoring stockpile management, concrete batching, mixing, transporting, placement, consolidation, finishing, and curing to ensure conformance with specifi cation requirements;
5.Maintaining and submitting all QC records and reports;
6.Directing the necessary corrective action to ensure continual conformance within the QC action limits;
7.Suspending production for the project when suspension limits are exceeded; and
8.Conducting or monitoring adjustments to the JMF .
E.QC Laboratory Requirements. Laboratories, including field laboratories and all associated testing equipment that prepare concrete mixes or perform QC testing, must demonstrate to the Engineer that they are equipped, staffed, calibrated, and managed to be capable of batching and testing concrete in accordance with the applicable test methods and procedures . Mix designs and their accompanying JMFs must include a MDOT Standard Specifications for Construction Section 1002
10-19 statement signed by an MCA -certified Michigan C oncrete Technician
Level II that all applicable standard test methods have been followed in verifying the mix design and JMF.
F.QC Sampling and Testing . Do not continue production of nonconforming work . Perform sampling, testing, and initial curing according to ASTM C31/C31M.
1.Provide the Engineer a minimum of 24 hours of notification prior to each concrete placement.
2.Conduct startup sampling and testing of concrete for temperature, slump, density (unit weight), and air content on the first load. Do not place concrete until testing verifies that the fresh concrete properties have not exceeded the QC action and suspension limit thresholds specified in Table 1002-1 . Continue testing subsequent loads as described in the QC plan for each grade of concrete del ivered to the work site each day . The QC sampling and testing must be independent from the Department ’s QA sampling and testing. Table 1002- 1: QC Action and Suspension Limits Quality Characteristic Action Limits Suspension Limits Air content (a) <5.0% or >9.0% Air content change (a) >1.5%(b) Conc. temp. As defined in the Contractor ’s QC plan(c) <45° F or >90 °F at time of placement Slump (max.) (inch) See Table 1004- 1, notes ( c) through ( n) Density (unit weight) N/A Aggregate gradation Refer to procedure for Optimized Aggregate Gradation in the contract.
a.Action limits for air content must be defined in the Contractor ’s QC plan and cannot be <5.5% or >8.5 %.
b.Suspend work if the air content of fresh concrete after adjusting for the change through a pump exceeds the suspension limits after the pump or paver, regardless of the air content change.
c.Concrete exceeding the maximum specified limit for slump and temperature requirements must be rejected regardless of th e total mixing time at the time of arrival to the project.
3.Prior to initial concrete placement, the testing personnel for both the Engineer ’s QA and Contractor ’s QC will conduct side -by-side correlation testing of the same concrete sample to verify correlation of both the Department ’s and the Contractor ’s test results for air content of fresh concrete. A sample is considered a representative quantity of concrete taken during production which is used to measure the quality characteristics for the concrete. Additional side-by -side correlation MDOT Standard Specifications for Construction Section 1002
10-20 testing will be conducted whenever there is a change in QC ’s or QA ’s
equipment or testing personnel for the project, or if the Engineer determines that there is a significant difference between the QC and QA test results. If the air content results of the side- by-side tests conducted by the QC and QA testers and equipment differ by more than 0.8% air by volume of concrete, a referee air content test must be conducted by a third party, des ignated by the Engineer but independent of the project, before the beginn ing or continuation of concrete placement in order to resolve issues associated with non-correlation.
4.Provide the curing facilities in accordance with subsection 1003.03.G prior to st art of concrete production.
5.Perform QC sampling and testing for air content change of fresh concrete that is either slip formed or pumped as described in the QC plan. Sample and test a representative haul unit of concrete immediately after its discharge but before the slipform paver or pump hopper . Sample and test the concrete representing the same haul unit, again, after the slipform paver or after discharge from the pump (without interruption or alteration of the pumping operation). If the difference in m easured air content between the two test locations for the same concrete is greater than 1.5% air by volume of concrete, suspend operations and administer corrective action. Resume concrete placement only after taking the necessary corrective action to red uce the change in air content of fresh concrete between the two test locations, as approved by the Engineer. If corrective action is required, document the corrective action(s) in the QC records and make the necessary adjustments in the QC plan. The Engineer may require the Contractor to administer additional QC sampling and testing if the Engineer determines that the Contractor ’s current QC sampling and testing methodology is shown to be insufficient to ensure continual control of the quality of the concrete.
6.Take the appropriate corrective action, as described in the QC plan, when QC testing shows that the QC action limits for any quality characteristic have been exceeded. Suspend production if any of the QC suspension limits have been exceeded or if the c orrective action is not sufficient to restore the quality to acceptable levels.
7.Resume production only after making all necessary adjustments to bring the mixture into conformance with all applicable specifications and receiving approval to resume work from the Engineer . Document the adjustments in the QC records. MDOT Standard Specifications for Construction Section 1002
10-21 G. Work Progress Specimens. Ensure that the strength of pavement and
structure concrete meet the requirements of subsection 104.11.B for opening to construction traffic or vehicular traffic, removing shoring or forms, or conducting similar operations . Determine concrete strength by making a series of test cylinders or beams . Cure the specimens in the same manner as the pavements or structures they represent . Allow the Engineer to witness the testing of the work progress cylinder or beam specimens and non-destructive testing, including calibration tests . Work progress samples are defined as an average of two specimens . Adjust operations as necessary to conform to the specified concrete strength requirements. The maturity method may be used at no additional cost to the Department after submitting a plan to the Engineer for approval to estimate the in-place flexural strength and determine compliance with opening-to -traffic requirements . Establish t he necessary preliminary flexural strength v ersus time-temperature factor correlations using the same materials and JMF as the project and in accordance with Department procedures.
H.Reduced QC for Small Incidental Quantities. Reduced levels of on-site QC te sting for concrete may be considered for small incidental quantities. Unless approved by the Engineer, multiple small incidental quantities, including ones that are placed consecutively throughout the project on the same day, are not eligible for reduced Q C consideration if the total plan quantity of concrete for the item exceeds 100 cubic yards. Include details for reduced QC testing and oversight in the approved QC plan in accordance with following:
1.The small incidental quantity of concrete will be limited to a single day’s concrete placement of a maximum 20 cubic yards;
2.The small incidental quantity of concrete is not an integral part of a structural load- bearing element;
3.The Engineer has received written certification from the Contractor that the concret e supplier has a current QC plan in place and available for review upon request by the Engineer;
4.The concrete supplier employs an MCA -certified Michigan Concrete Technician Level II available at the plant or on call during concrete placement to validate and authorize modifications to the concrete JMF;
5.Prior to the first concreting operation, concrete representing the JMF for the small incidental quantity has been sampled and tested by an MCA -certified Michigan Concrete Technician Level I or Level II to verify that, historically, the JMF produced a concrete mixture meeting MDOT Standard Specifications for Construction Section 1002
10-22 the minimum requirements for density (unit weight), slump, air content,
and strength. Annual verification may be acceptable provided there are no changes to the material types or sources, i ncluding the cementitious materials and admixtures;
6.The Engineer verifies that the temperature, slump, and air content conform to specification requirements at the start of the day ’s concreting operation associated with the small incidental quantity; and
7.The Engineer is notified a minimum of 24 hours prior to concrete placement. 1002.04. Measur ement and Payment All costs associated with this work are included in the unit prices for the relevant concrete items . The Department will not pay separately for providing and maintaining an effective QC program.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 1053–1060 of 1,146.