Ready-Mix Concrete – Producer

Weeks/months prior to batching Agency Concrete

  • Certify plant and lab scales utilizing an Authorized Scale Calibration Company.  Calibration of weighing Equipment is required within three months prior to plant certification each calendar year.  A list of authorized companies can be found under the Certified Ready-Mix Program References:  http://www.dot.state.mn.us/materials/certifiedrm.html
  • Check lab testing equipment for wear and/or damage and order new or repair if necessary
  • Order lab supplies o Wire lab brushes o Soft lab brushes o Spatulas, scoops, and spoons
    • Adequate number and size of pans for performing moisture tests and drying of the aggregates for gradations
    • Buckets for Aggregate sampling
    • 1 gallon freezer bags for fine aggregate QA samples o Coarse aggregate sample bags for QA samples o Fine point permanent markers for sample identification
  • Ensure all aggregates have been approved for use in Agency projects o Concrete Aggregate Properties and approved quality types of use can be found under the Certified Ready-Mix Program References link: 

http://www.dot.state.mn.us/materials/certifiedrm.html

    • If using a new source for either the coarse or fine aggregate, the new source testing requirements link can be found on the same webpage as the Concrete Agg Properties 
  • Submit Project Specific and/or General Mix Designs to the MnDOT Concrete Office a minimum of 21 days prior to the placement of the concrete
  • Ensure cementitious and admixture sources are on MnDOT’s Approved/Qualified Products List at:  http://www.dot.state.mn.us/products/concrete/index.html
  • Certify the plant- Contact: 
    • The MnDOT District Independent Assurance Inspector or; o Concrete Office to schedule an onsite inspection of the plant
  • Download and save a copy of the Aggregate Gradation Control Charts and Sample Log from the

MnDOT Concrete website at:  http://www.dot.state.mn.us/materials/certifiedrm.htmlo This document will be used throughout the remainder of the year

  • Perform Gradations as necessary to ensure material meets Specifications (3126 and 3137)

 

Days Prior to the Project Start Date

  • Verify mix designs intended for use on the project have been reviewed and are signed by

MnDOT Concrete Office personnel o Approved General Mix Design Sheet numbers will be listed on the Concrete Engineering
Unit’s website at:  https://rmx.dot.state.mn.us/rm_mix/o Project Specific Mix Designs must have the project listed on the mix design sheet (Check with the Project Engineer or Contractor placing the concrete for the Project Number)

  • Verify aggregates that will be used in the Agency work are onsite o Check stockpiles for contamination, segregation, and interblending

o Perform gradations as necessary and document results in the QC Workbook and Control Charts to ensure material meets Specification

  • Verify the cementitious materials that are going to be used in the Agency work are listed on the

Contact Report and are on the APL o If not, verify new materials are on MnDOT’s APL and obtain a 5 lb sample and save for the Plant Monitor.  Update the Materials section of the Contact Report and submit to
MnDOT Concrete Office o General mixes allow for cementitious substitutions if they are listed on the APL.  In contrast, Project Specific Mix Designs are required to use all components listed on the approved mix design sheet

  • Verify the admixtures that are going to be used in the Agency work are listed on the Contact

Report and are on the APL o Any admixture can be used for General Mixes except for Types C and E.  Type C and E accelerating admixtures require the approval of the Concrete Engineer/Project
Engineer o Project Specific Mix Designs must have admixtures and dose rates listed on the mix design.  Some admixture dose rates on the mix design may be listed as 0 oz - xx oz/cwt therefore they may or may not be used throughout an entire pour depending on the Project’s requirements

  • Request a copy of the Project’s Schedule of Materials Control from the Project Engineer to ensure minimum testing rates will be met as specified in the contract.
  • Check all component batch weights (Fine and coarse aggregates, cementitious, water, etc.) in the batching system for all mixes that will be used to verify they match the MnDOT approved Mix Design weights 

                

Day/Week of Agency Production- Sampling, Testing and Electronic Documentation

  • Spot check actual batching to verify batch weights and toleranceso Check each component in the mix including the admixtures for proper weights and dosages
  • Check aggregate stockpiles for contamination, segregation, and interblending
  • Download the latest version of the Concrete Ready-Mix QC Workbook at: 

http://www.dot.state.mn.us/materials/certifiedrm.htmlo This workbook is to be used for one week onlyo The week ending date is always on Saturday of that week
o After the Agency work has been performed, the Quality Control Supervisor will review the Workbook and submit it by Tuesday of the following week to:

    • The Project Engineer
    • The Concrete Engineering Unit at:  weeklyrmplantreport.dot@state.mn.us
  • Perform Aggregate Moisture Tests on representative material every 4 hours
  • Document Moisture Test results in that week’s QC Workbook in Real-Time 
  • Perform Aggregate Gradations on representative material at a rate defined in the Project’s Schedule of Materials Control.  The Time on the Concrete Aggregate Worksheet should be the time the sample was taken and not the time it was tested.
  • Document Gradation results in that week’s QC Workbook AND the Aggregate Gradation Control Charts in Real-Time
  • Record all Aggregate samples taken by the Department in the Control Chart/Sample Log
  • Record all cementitious and admixture samples taken by the Producer and picked up by the Department
  • QC Workbooks and the Control Chart/Sample Log must be completed in Real-Time using the Producer’s Certified Technician’s full name for the Diary and each test performed.


•

If a gradation fails to meet Specification immediately take another gradation o If the 2nd gradation passes, resume testing as required by the Schedule of
Materials Control o If the 2nd gradation fails, STOP PRODUCTION and contact the Project Engineer o Resume production when corrective action results in a passing gradation o Record ALL gradations in the Control Charts whether they have passed or failed

•

If the Moving Average of 4 consecutive tests is outside of gradation limits on any sieve:

  • STOP PRODUCTION and contact the Project Engineer o Determine the cause of the failing or borderline material
  • Resume production when corrective action results in a passing gradation o Increase testing at a rate of 1 per 100 yd³ until the moving average is within gradation limits

Certificate of Compliance Review

*Note:  This is a partial list of required information on a Certificate of Compliance.  Please refer to the Contact Report for a complete list of requirements.

  • Plant name and Location/address
  • Project and/or Bridge Number
  • Approved Ready-Mix (RMX) Sheet Number (XXX-XXX)
  • MnDOT Mix Designation
  • Date/Time of Batch
  • Cubic Yards
  • Cubic Yards daily cumulative
  • Correct Aggregate sources (MnDOT pit number)
  • Correct MnDOT approved Standard Abbreviations for all other sources
  • Total Moisture Factors (MCFac) for all aggregates match line F from the most recent moisture test
  • Absorption Factors (AbsFac) for each aggregate match the mix design AbsFac’s
  • Verify weights listed in the OD column match the mix design
  • Ensure weights listed in the Actual column are within tolerance of the Target Weights of the batch.  Verification of weights can be performed in the Certificate of Compliance Check tab in the QC Workbook but is not a requirement.
  • Total Water must be less than Design Water.  The load should be rejected if the Total Water is more than Design Water in any batch!  Total Water vs. Design Water can be verified on the Certificate of Compliance Check tab in the QC Workbook, but it is not required to be filled out.
  • The Producer’s certified Technician will review the first ticket for each mix type each day for accuracy and:
    • o Print their name and Tech ID Number o Hand sign their name in the designated location
       

Maintaining Plant Certification

The Producer will maintain plant certification by:

  • Displaying the current Contact Report – ready-mix and site map in plain sight at all times
  • Updating the Contact Report – ready-mix with any Material or Equipment changes and submitting to the Department
  • Making Producer plant QC workbook and QC charts available electronically at all times • Performing the responsibilities identified in 2461.3F.3, “Contractor Quality Control (QC)”
  • Supplying the following information at the request of the Engineer:
    • Approved mix design sheets o Agency cementitious and admixture test results o Agency verification gradation test results o Aggregate quality test results
    • Keep plant reports, charts, and supporting documentation on file at the plant site for 5 calendar years.

Certified Ready-mix Plant Decertification


The Concrete Engineer, with coordination from the Engineer, may decertify the plant and halt production of concrete under any of the following conditions:

  • Unauthorized procedural, Material, or Equipment changes made after the completion of the Contact Report – ready-mix
  • Failure to meet the required testing rates
  • Failure to complete required documents
  • Failure to provide competent Department Certified Plant Technicians
  • Disregard of any of the requirements of 2461.3F, “Certified Ready-mix Concrete” • Falsification of test records or Certificates of Compliance

 

Please call someone from the MnDOT Concrete Engineering Unit or the MnDOT Independent Assurance Inspector in your district if you have questions concerning the Certified Ready-Mix Plant Program!

 

Contacts

Brad Swenson – Greater Mn Plant Specialist Northern Region – Districts 1, 2, 3A, 4
Cell: 218-232-1012
bradley.s.swenson@state.mn.us

Mike Daniels – Greater Mn Plant Specialist Southern Region – Districts 3B, 6, 7, 8
Cell: 320-293-9421
michael.daniels@state.mn.us

Matt Herbst – Plant Specialist Metro Region
Cell: 651-283-7127
matthew.herbst@state.mn.us

Gordy Bruhn – Field Engineering Specialist (Field issues – Low Cylinder Strengths – Paving Rehab)
Cell: 651-398-9597
gordon.bruhn@state.mn.us

Jake Gave – Assistant Concrete Engineer - Structural, High Performance, SCC, and Mass Concrete
Cell: 612-554-9289
jacob.gave@state.mn.us

Rob Golish – Assistant Concrete Engineer – Paving, Joint Layouts, Approved/Qualified Products
Cell: 651-216-0516
robert.golish@state.mn.us

Maria Masten – Concrete Engineer – Specs, Standard Plans, Material Failure Recommendations
Cell: 651-334-4015
maria.masten@state.mn.us

MnDOT District Independent Assurance Inspectors (IAI)

D1 Duluth - Nadine Miller - (218) 348-6297
D2 Bemidji -Raymond Wesley - (218) 766-6949
D3 Baxter - Matt Miles - (218) 232-6748
D4 Detroit Lakes - Casey Clarke - (218) 849-7393
D6 Rochester - Dennis Hayes - (507) 251-0138
D7 Mankato - Mitch Jordahl - (507) 380-9619
D8 Willmar - Paul Janke - (320) 212-5739
Metro/West - Karl Sinclair - (651) 775-0998
Metro/East - Kaleb Kollmann - (651) 478-0339
Metro/East - Kris Westerbur - (651) 775-1151
Metro/West - Zach Lyrek-Hanks - (651) 775-1018
Metro IA Office - (651) 234-7356