10-23 Section 1003. Quality Assurance (Acceptance) for Concrete
1003.01. Description Unless otherwise specified, all concrete provided and placed on the project is covered by the Department ’s concrete QA program . The Engineer will sample and test concrete for acceptance as part of its QA procedures in accordance with this section . 1003.02. Materials None specified. 1003.03. General Requirements
A.Department QA Plan Considerations. The Engineer is responsible for administering the quality -based acceptance and will institute any actions necessary toward its successful implementation. The Engineer will not accept concrete at a reduced price as an alternat ive to the Cont ractor ’s making adjustments to bring work into conformance. The nominal QA strength test specimen size must be noted in the QA plan. The Engineer will develop and follow a QA plan. The Engineer will provide the QA plan to the QC Administrator a minimum of 7 days prior to the pre-production meeting. The QA plan will be reviewed at the pre-production meeting, and any proposed changes will be documented.
B.Personnel Requirements . Sampling for concrete will be performed by a n MCA -certified Michigan Concrete Technician Level I or Level II . Aggregate sampling for concrete will be performed by a n MCA -certified Aggregate Technician Level II.
C.Contractor Provided Mixtures . Provide mix design and accompanying JMFs using the methods of verification in this subsection. Include sufficient information on constituent materials, admixtures, optimized aggregate gradation analysis when required, trial batch verified physical properties of the fresh concrete, mix proportions per cubic yard, and compressive strength test results necessary to allow the Engineer to fully evaluate the expected performance of the concrete mixture. Follow ACI Standard 211.1 for all mix designs .
1.Mixture Documentation . Prepare mix designs for each grade of concrete required on the project . Submit JMF for each mix design and all required documentation to the Engineer for review 14 days before the anticipated date of placement . The Engineer will notify the MDOT Standard Specifications for Construction Section 1003
10-24 Contractor of any objections within 7 days of rec eiving the mix
documentation. Identify each JMF and reference all accompanying documentation to this identification. Reference each JMF to the appropriate method of verification. Mix design and JMF submittals that do not include all required documentation are incomplete, and the Engineer will return them without review. Mix documentation is valid for 2 years provided the material characteristics have not deviated beyond the requirements specified in the contract. All mix designs and accompanying JMFs must be traceable t o a laboratory meeting the requirements of subsection 1002.03.E. Submit mix design and JMF on MDOT Form 1976, JMF Concrete Field Communicator , including project -specific or historical laboratory test data. Include the recorded air content of fresh concrete using the same admixture and cementitious material sources to be used in the production of the concrete for the project . A JMF will be approved only if all of the minimum mix design requirements specified in the contract have been met.
2.Job Mix Formula (JM F). Select proportions for concrete mixtures according to ACI Standard 211.1. The volume (oven- dry-rodded) of coarse aggregate per unit volume of concrete must be 65 %, minimum . For concrete mixtures using optimized aggregate gradation, the above specified volume of coarse aggregate per unit volume of concrete includes the intermediate aggregate. Provide the necessary ASR documentation per Department requirements. The following f our methods of verification of proposed JMF are acceptable.
a.Method 1 – Trial Batches. Trial batch verification of JMF requires using the same materials and proportions in the trial batches as proposed for the project mix designs . Prepare at least one trial batch for each mix design in sufficient time before starting concrete placement to allow for review according to subsection 1003.03.C.1. Provide the results of temperature, slump, density (unit weight), air content of fresh concrete, 28- day compressive strength, and age of concrete at the time of strength testing, for a minimum of three independent samples . All samples may be taken from a single trial batch for a mix design provided the trial batch is at least 4 cubic yards. MDOT Standard Specifications for Construction Section 1003
10-25 For JMF trial batch verification purposes only, 7-day compressive
strength test results that report at least 70% of the specified 28-day lower specification limit are sufficient documentation instead of 28-day compressive strengths . The average of at least two strength test specimens represent one compressive strength sample test result for each independent sample.
b.Method 2 – Same Mixture. Verification of JMF is based on the concrete producer ’s experience with the same mix design, JMF, and the same materials. Provide the results of temperature, slump, density (unit weight), air content of fresh concrete, 2 8-day compressive strength, and age of concrete at the time of strength testing, for a minimum of three independent samples . The average of at least two strength test specimens represents one compressive strength sample test result for each independent sam ple. Do not substitute material types or sources, including admixtures or cementitious materials, or change mix proportions in the JMF.
c.Method 3 – Similar Mixture . Verification of JMF is based on the requirements described in Method 2. Substitution of coarse and intermediate aggregate sources is permitted if the new source is of the same geologic type as the original aggregates and conforms to the specification requirements for the application. Substitution of fine aggregate is permitted only if the new source has been tested for ASR. Provide the supporting laboratory trial batch documentation and accompanying calculations showing how the mix proportions in the JMF were adjusted, based on the documented differences in relative density (specific gravity), bulk density (unit weight), and absorption of the substituted aggregate sources, to produce a theoretical yield of 100% and the required fresh concrete properties.
d.Method 4 – Annual Verification . At the Engineer ’s discretion , verification may be accepted annually for a concrete producer rather than on a project basis, provided the sources and proportions of the constituent materials, including cementitious materials, source, and types of admixtures, do not change. If the project is the cont inuation of work in progress during the previous construction season and written certification is submitted to the Engineer that materials from the same source and with the same mixture properties are to be used, the Engineer may waive MDOT Standard Specifications for Construction Section 1003
10-26 the requirement for annual renewal verification of the JMF for the
project.
D.Department Provided Mixtures. Unless otherwise specified in the contract or approved by the Engineer, the Engineer will provide the concrete JMF for the following types of concrete regardless of the total quantity for the project:
1.Structural concrete patching mixtures, mortar, and grout;
2.Bridge deck overlay concrete mixtures; and
3.Project -specific concrete mixtures and grades not defined in Table 1004-1 . Provide the necessary ASR docu mentation per Department requirements.
E.Changes in Materials and Properties. Any change from one approved JMF to another for the same grade of concrete must have prior approval by the Engineer. Prior to batching, verify that the proposed JMF changes will not affect the properties of the fresh concrete (slump, temperature, air content, density [unit weight ], workability) or result in deleterious mortar bar expansion as a result of ASR per Department requirements. Resubmitting the mix design and its accompanyi ng JMF is not required when adjusting the aggregate mix proportions included in the approved JMF in order to maintain optimization of the aggregate gradation in accordance with the contract. Record all changes to JMF in the QC records along with the ration ale for the change.
F.QA Laboratory Requirements. The testing laboratory with responsibility for acceptance testing on the project is the MDOT Region’s testing laboratory or a qualified facility under the authority of the Engineer.
G.Initial Curing Facilities . The Contractor will provide curing facilities equipped to ensure the proper environment for the Department ’s QA concrete strength test specimens during initial cure. Each initial cure facility must provide ventilation or insulation, as directed by the Eng ineer, to ensure that the ambient temperature surrounding the specimens is maintained according to ASTM C31/C31M . Each initial curing facility must be capable of being locked using a Department -provided padlock . The Contractor must ensure that all initial curing facilities are accounted for at all times and protected against theft and damage. The Contractor must place and secure each initial cure facility throughout the project limits to MDOT Standard Specifications for Construction Section 1003
10-27 minimize excessive transport of the test specimens prior to initial cure, as
follows:
1.Immediately after finishing molded specimens, the Engineer will move the QA concrete strength test specimens to the closest initial cure facility.
2.Immediately after all QA concrete strength test specimens are placed into the cure facility and the proper initial curing conditions have been established, the Engineer will secure the facility using the Department -provided padlock . Access to the QA concrete strength test specimens thereafter must be coordinated with the Engineer and is only permitted in the presence of the Engineer.
3.The Engineer will transport the QA concrete strength test specimens as described in the QA plan within 48 hours after molding, but not prior to 8 hours after final set of the concrete, from the initial curing facility to the Department ’s designated testing laboratory for final curing and strength testing. The specimens will be protected with a suitable cushioning material to prevent damage from jarring during transport . The total transportation time must not exceed 4 hours prior to commencement of final curing.
H.QA Sampling and Testing . The Engineer will verify the Contractor ’s daily startup sampling and tes ting of temperature, slump, and air content of fresh concrete on the first load; conduct QA sampling and testing; monitor Contractor adherence to the QC plan; and inspect field-placed materials in a manner that ensures that all concrete for the project is represented. The testing correlation requirements of subsection 1002.03.F.3 must be met prior to concrete placement. Samples for acceptance will be taken at the point of discharge from the haul unit at approximately the middle one-third of the load. Mix adjustments to the concrete contained within the haul unit selected for QA sampling and testing (beyond normal QC) are not permitted prior to QA sampling and testing. QA sampling will take place without prior notification. The Engineer will perform QA sampli ng and testing for air content change of fresh concrete that is either slip formed or pumped at least once during each day of production. The Engineer will s ample concrete from a representative haul unit immediately after its discharge but before the slipform paver or pump hopper . The Engineer will s ample and test the concrete representing the same haul unit after the slipform paver or after discharge from the pump without interruption or alteration of the pumping operation. MDOT Standard Specifications for Construction Section 1003
10-28 The Engineer may perform additional testing on concrete that is pumped
whenever the pump is relocated or whenever there is a significant change in the boom configuration or operation of the concrete pump . The Engineer may perform additional testing whenever there are significant changes in the paving operation. The location(s) within the project limits for QA testing of the fresh concrete and placement of curing facilities for initial curing of the 28-day compressive strength QA test cylinders will be determined by the Engineer in conform ance with the following criteria:
1.The time between obtaining the first and final portions of the composite sample must not exceed 15 minutes;
2.Testing for slump, temperature, and air content of fresh concrete must begin within 5 minutes after obtaining the final portion of the composite sample;
3.Molding of the 28-day compressive strength QA test cylinders must begin within 15 minutes after obtaini ng the final portion of the composite sample; and
4.The concrete sample must be protected from the sun, wind, and other sources of rapid evaporation and from contamination.
I.QA Records. The Engineer will maintain a complete record of all QA tests and inspections . The records will contain signed originals of all QA test results and raw data, random numbers when used, and resulting calculations . The QA test results will be submitted to the Contractor 24 hours after the Engineer receives the QC results.
J.Small Incidental Quantities . At the discretion of the Engineer, daily 28-day compressive strength QA test cylinders for small incidental quantit ies of concrete may not be required provided QA test cylinders representing the same JMF were sampled and molded at least once during the same week . Follow small incidental quantity requirements per subsection 1002.03.H.
K.Lot Size and Makeup . Lot size and makeup will be determined by the Engineer based on site conditions . A production lot may consist of a single day’s production, individual concrete structural elements, or a combination provided they are of the same JMF . A production lot will not include more than one grade of concrete, concrete of the same grade that has different specified slump or air content, or concrete of the same grade that has different mix designs or JMFs. Consecutively placed concrete mixes where the aggregate proportions were adjusted to maintain an optimized gradation may be included in the same production lot provided they are the same grad e and same JMF. MDOT Standard Specifications for Construction Section 1003
10-29 Each production lot will be divided into sublots of approximately equal
size, as determined by the Engineer . The minimum number of sublots will be one per production lot, with the maximum number of sublots based on the anticipated total qua lity of concrete to be placed and site conditions . A minimum of one sublot will be required for each day of production.
L.Random Numbers . Random numbers are used to determine sampling locations when required by the contract. Prior to the pre -production meeti ng, the Engineer will generate a list of random numbers using a spreadsheet program or a calculator . The random numbers will be used to designate when QA samples are taken based on cubic yard quantities. At the pre-production meeting, each page that lists random numbers will be signed by the QC Administ rator and the Engineer . Each sheet containing the random numbers will be covered by a separate sheet of paper in order to prevent disclosure of the random numbers. The original signed list will be placed in t he project file and a copy will be provided to the Engineer ’s field inspector for the project. When the project is completed, a copy of the list of random numbers will be provided to the Contractor upon request.
M.QA Stop Production Criteria . If one or more of the following occur, t he Engineer will issue MDOT Form 1165 and concrete production must be stopped:
1.The QA testing shows that one or more of the suspension limits for quality characteristics defined in Table 1002 -1 are in non-compliance;
2.The QC plan is not being followed;
3.Segregation, excessive slumping of unsupported slip formed edges, or other notable changes in the fresh concrete properties is or are observed that may prevent proper placement or consolidation and finishing of the finish ed product;
4.The required curing system is not being applied;
5.If the measured air content change between the two testing locations for the same concrete is greater than 1.5% air by volume of concrete as described in subsection 1002.03.F.5 and 1003.03.H; or
6.If the air content of fresh concrete after adjusting for the change through a pump or a paver exceeds the suspension limits in Table 1002-1 after the pump or paver, regardless of the recorded QC or QA air content change through the pump or paver. MDOT Standard Specifications for Construction Section 1003
10-30 The Engineer will issue a Notice to Resume Work from MDOT Form 1165
only after all necessary adjustments have been made to restore conformance with all applicable specifications and the appropriate documentation has been added to the QC records. 1003.04. Measurement and Payment All costs associated with this work are included in the unit prices for the relevant concrete items.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 1061–1068 of 1,146.