Business Center

Flowchart 9C: Materials

Full Flowchart

You can also dig more deeply into the separate pieces of the flowchart below.


The CDOT project manager submits an electronic copy of the award set of plans and specifications, and an engineer's estimate or tabulation of bid items to CDOT staff materials in the Materials and Geotechnical Branch. The project manager requests creation of CDOT Form 250, Materials Documentation Record. The CDOT project manager also submits a copy of the award set of plans and specifications to the region materials engineer, who creates the CDOT Form 379, Independent Assurance Testing Schedule. To expedite the creation of these forms, the local agency should make certain the items and quantities for these submittals are in CDOT format, using CDOT item codes.

Guidance on activities before, during and after construction—as well as proper completion of CDOT Forms 250 and 379, and Form 473LA, Letter of Materials Certification—can be found in the "Documentation – Local Agency Project Materials to Final Materials" document under "Resources" on this website. Also, see "Resources" for an example of a completed CDOT Form 250 and CDOT Form 379, and for Form 250 Development Guidelines.

The CDOT Form 250 is generated by CDOT to track materials used on local agency projects and the number of tests needed. It also identifies the forms used to record test results. The form designates test frequencies for project acceptance testing and laboratory check testing. The initial CDOT Form 250 is developed from the award set of plans and specifications, and updated by your agency as work progresses.

The CDOT project manager forwards CDOT Form 250 and CDOT Form 379 to you prior to the preconstruction meeting. You should review CDOT Form 250 to be aware of the types and frequencies of tests that the project quality assurance tester will perform. You should also review CDOT Form 379 to be aware of the frequency of the independent assurance tests that will be performed.

If CDOT Form 379 indicates independent assurance testing is required and you are not the responsible party, you will coordinate with the CDOT project manager and then the independent assurance tester to make certain that testing will be performed on schedule. See text box 9C.11 for further information.

Independent Assurance Test Notification
If CDOT performs the independent assurance testing, you are responsible for notifying the CDOT region independent assurance tester a minimum of one week prior to the start of work on the project, and a minimum of one week prior to the need for the independent assurance tester as defined on the CDOT Form 379.

You may contract with a materials testing consultant to provide sampling, testing and inspection services shown on CDOT Form 250. The materials consultant and testing laboratory must have appropriate certifications, as described in the CDOT Field Materials Manual. All personnel performing sampling, observations, and testing on CDOT or local agency projects are required to be qualified personnel, as noted in Section 8, "Sampling and Testing Personnel Qualifications," and/or Colorado Procedures 10, "Qualification of Testing Personnel and Laboratories."

You are responsible for assembling the materials binder in accordance with the format in the "Owner Assurance (OA) Frequency Guide Schedule for Minimum Sampling, Testing and Inspection," found in the "Documentation – Local Agency Project Materials to Final Materials" document under "Resources." This guide should be used to establish the initial materials binders and maintain them throughout the project.

The guide is the essential document to use when determining which CDOT forms to use as worksheets, which CDOT forms to collect as test reports, and what materials acceptance documents are required. It is not inclusive of every materials item, but it references primary items that you will encounter. It is critical to follow the item numbering in sequential order to aid in locating project paperwork. Contact your CDOT project manager to determine if these documents may be maintained electronically.

If you are responsible for performing independent assurance testing, you may contract with a materials testing consultant and laboratory for these services.

In advance of the preconstruction meeting, you should:

  • Review the project plans and check the project special provisions for any modified testing procedures.
  • Review the CDOT Form 250 and CDOT Form 379.
  • Set up the project material books (materials binder—See text box 9C.7).
  • Review the Special Notice to Contractors under Resources on this website, making note of the applicable acceptance level for the materials being incorporated into the project.
  • Ensure items and testing frequencies included in other work are accounted for in CDOT Form 250, CDOT Form 379 or for pre-inspection.
  • Develop a list of pre-inspection items and notify CDOT project manager prior to pre-inspections.
  • Collect submitted list of proposed material suppliers from the contractor.
  • Evaluate the contractor's materials suppliers list against the requirements of CP11- Quality Management Plans and the Qualified Manufacturers List, the Qualified Manufacturers List (QML) and the Approved Products List (APL).
  • Identify sources of undesignated materials.
  • Set up random sampling schedules (CP75—Stratified Random Sampling of Materials).
  • Assure concrete mix design approval, if required.
  • Assure asphalt job mix formula approval, if required.
  • Schedule and participate in a pre-testing meeting. Use CP16—Management of CDOT & Consultant Materials Testing's Pre-Testing Meeting Agenda (CDOT Form 1322), if applicable. You and the CDOT project manager will determine if a special meeting is needed with the CDOT region materials engineer to discuss and define material issues concerning the project, or if materials can be discussed adequately at the regular preconstruction meeting. As part of this determination, you and the CDOT project manager will also review the LA contract administration checklist, CDOT Form 1243 (Section 9) from the Intergovernmental Agreement.
  • Laboratory verification tests and/or acceptance test methods should be defined (e.g., AASHTO, American Society for Testing and Materials, Colorado Procedures, Colorado Procedures—Laboratory, or Marshall vs. Superpave Gyratory compactor). The CDOT Field Materials Manual, CP 13, gives guidance for check testing. With CDOT's concurrence, you approve the laboratory to perform check tests.

Your project engineer chairs the preconstruction meeting and introduces staff, discusses their roles and addresses any remaining questions regarding materials testing coordination.

During construction, your or your consultant consultant's responsibilities include:

  • Perform owner assurance (project acceptance) samples and tests.
    Project acceptance samples and tests are used to determine the quality and acceptability of the material being sampled, and workmanship that have been or are being incorporated into a construction project. The samples and tests are taken and performed by you or your agency's approved personnel. Sample and test according to the Random Sample Schedule (See text box 9C.8).
    • During construction: Acceptance testing and documentation follows the applicable CDOT Field Materials Manual, or approved equivalent, and the project specifications. You or your consultant completes on a daily basis the sampling and testing documentation (worksheets and reports).
    • Non-specification material: If specification material is not being produced or provided, you take appropriate action as defined in the specifications (i.e., price reduction, rejection or non-payment). For further direction, refer to Section 105 of the CDOT Standard Specifications. This action may trigger the need for a change order. Any price adjustments should be shown on the monthly progress estimates. You or your consultant should keep a list of exceptions to specifications and update it on a daily basis. Each exception should have a written explanation, which should be kept in the project file. This information will be used to complete CDOT Form 473LA at the end of the project.
    You communicate the field-adjusted quantities from any change orders to the region materials engineer and the IA tester.
  • Perform laboratory verification tests.
    You or your consultant submits random representative samples to your approved laboratory to verify acceptability of field-produced material. The laboratory performs tests that generally are not within the capabilities of the owner assurance (project acceptance) testers' equipment.
  • During construction
    Your approved laboratory performs the laboratory verification tests (refer to the Central Lab column in the CDOT Field Materials Manual Owner Assurance Schedule—QA Frequency Guide Schedule for Minimum Materials Sampling, Testing, and Inspection) at the frequency in the Field Materials Manual and/or in the specifications. The purpose of verification tests is to assure that all materials incorporated into the project meet the design and specifications.
  • Update CDOT Form 250.
    Ensure that all required information is added to the Form 250 as testing progresses. It is very important to complete the applicable portions of the last five sections of the Form 250 (Documentation for Added Materials Items, Documentation for Deleted Materials Items, Summary of Laboratory Check Test Deviations, Summary of Sampling and Testing Deviations, and Summary of Project Price Reduction Documentation) at the time the information becomes available.
  • Participate in materials testing meetings – As necessary, you or your consultant conduct weekly materials testing meetings with the CDOT project manager. Use CP16—Management of CDOT & Consultant Materials Testing's Pre-Testing Meeting Agenda (CDOT Form 1322) if applicable.
  • Collect and review certificates of compliance (COCs) and certified testing results (CTRs).
    See the CDOT Construction Manual, Section 106.12 and Section 106.13 for additional information. These materials acceptance documents should be filed on a daily basis.
  • Collect Buy America certifications and submit them monthly to CDOT.
    These certificates should be provided to you by the contractor prior to incorporation into the project (if federal funds are included in the project). See Appendix B of the CDOT Construction Manual for examples of Buy America certifications submitted by the contractor to you for review.

The independent assurance testing program defines the tests required to provide an independent check on the reliability of project acceptance samples and tests. The Independent Assurance Testing Program is defined in the CDOT Field Materials Manual, Quality Assurance Procedures and Independent Assurance Schedule sections. Testing requirements are determined by planned quantity.

  • Prior to Construction
    For projects on the NHS: Federal law requires independent assurance testing on projects on the National Highway System. You may, under the direction and approval of the CDOT region materials engineer, administer the independent assurance testing program on projects, provided you use an AASHTO-accredited laboratory that is independent from the project-acceptance testing lab, uses qualified personnel for testing and observations, performs the calibration equipment checks, and follows all applicable sections of CDOT Field Materials Manual chapters on the Quality Assurance Procedures for Construction and Materials Sampling & Testing, and Independent Assurance Frequency Guide Schedule for Evaluation of OA Sampling & Testing.

    The initial CDOT Form 379—Project Independent Assurance Sampling Schedule—developed from the award set of plans and specifications, will be prepared by you or the CDOT region materials engineer as established on the CDOT Form 1243: Local Agency Contract Administration Checklist.

    For projects not on the NHS: CDOT requires independent assurance testing be performed as stipulated in the CDOT IA Frequency Guide Schedule for Evaluation of OA Sampling & Testing and within the Quality Assurance Procedures Chapter of the Field Materials Manual. You may use your agency's established and documented procedures to independently verify the adequacy of testing equipment and personnel if your program is approved by the FHWA.

    Independent assurance test notification: If CDOT performs the independent assurance testing, you are responsible for notifying the CDOT region independent assurance tester a minimum of one week prior to the start of work on the project and a minimum of one week prior to the need for the independent assurance tester as defined on CDOT Form 379.

  • During construction
    For projects on the NHS: The independent assurance testing laboratory or the CDOT Region Materials Laboratory will perform independent assurance testing and sampling as described on CDOT Form 379 as the work progresses. The independent assurance tester will update CDOT Form 379 as the assurance tests are performed. The independent assurance tester, in partnership with you, will address discrepancies in test values. Assurance test results will be distributed to you through the CDOT project manager and the region materials engineer when CDOT performs the independent assurance testing.

    For projects not on the NHS: Independent assurance testing will be performed as defined by your agency's policies and procedures.

As part of CDOT's oversight responsibilities, your project documentation will be reviewed during the project.

Guidance on activities after construction, as well as proper completion of CDOT Forms 250 and 379, and CDOT Form 473LA, Letter of Materials Certification, can be found in the documentation chapter of the current CDOT 2020 Field Materials Manual. Some of your responsibilities include:

  • Sort and arrange all documents within the Project Materials Books sequentially by item number and then by date for ease of review.
  • Use CDOT Form: 1199 Finals Materials Documentation Checklist, (Project Closure) Page 1, to document that the subsequent steps have been followed.
  • Compare final quantities from the latest progress estimate (Request for Reimbursement) to CDOT Form 250 final quantities.
  • Document on CDOT Form 250 the total number of tests taken by the owner assurance tester.
  • Verify that any shortages of required tests as indicated on CDOT Form 250 are explained.
  • Make sure all pre-inspected items have a CDOT Form 193, when applicable.
  • Ensure that all required documents from the contractor have been received, such as: Buy America certificates, CTRs, COC, etc.
  • Prepare and submit to the CDOT project manager CDOT Form 473LA, Letter of Materials Certification. The letter shall certify that the material incorporated into the construction work is in reasonably close conformity with the approved plans and specifications, and should consider added and deleted materials by CMO/Force Account.
  • Complete CDOT Form 1199: Final Materials Documentation Checklist, and (Project Closure). The following documents, or similar, shall be attached to the letter:
    1. CDOT Form 473LA: Letter of Materials Certification, Page 2, Explanation of Exceptions with all supporting documentation that addresses any exceptions or deviations.
    2. The completed CDOT Form 379: Project Independent Assurance Sampling Schedule.
    3. The completed CDOT Form 250, checked and signed by your agency's person in responsible charge. If a consulting testing firm is used on the project, CDOT Form 250 is required to be electronically sealed by a PE employed by the testing firm.

Distribute Final Independent Assurance Testing Results
For Projects on the NHS: The independent assurance testing laboratory, or the CDOT region materials laboratory completes and distributes the CDOT Form 379 and the explanation of deviations concerning the independent assurance testing program.

The contractor completes the Certificate of Compliance if using a manufactured item from the Approved Product List (APL) and submits it to you for approval.

You check to make certain the item is on the Approved Products List (APL). If the COC is approved, you notify the contractor who incorporates the product into the project.

Manufactured products are typically accepted based on pre-inspection (PI), certified test reports (CTR), certificates of compliance (COC), pre-approval (APL, listed on CDOT's approved products list website), or a combination thereof. In specific industries, the manufacturers must be first listed on the qualified manufacturers list (QML) before product acceptance can be considered. Refer to the Special Notice to Contractors in the applicable Field Materials Manual.

You contract with a qualified inspection firm and schedule the inspections. You also notify the CDOT project manager of the date and time for the inspections.

All mix designs for concrete and hot mix asphalt will be reviewed for acceptance by CDOT. Mix design approval is required prior to the use of any paving material.

Local agency responsibility for approving concrete and hot mix asphalt
If, in accordance with CDOT Form 1243, you are responsible for approving concrete and hot mix asphalt mix designs, and if required by the region, you submit the approved designs to the region materials engineer through the CDOT project manager. You may ask the region materials engineer to concur on the design mix. For approval of hot mix asphalt items, a form similar to CDOT Form 43: Job-Mix Formula should be used. The test results used to establish the job mix formula and the project specifications with the approved mix design submittal should be included. See CP 52 from the current Field Materials Manual for guidelines.

CDOT responsibility for approving concrete and hot mix asphalt
If, in accordance with CDOT Form 1243, CDOT is responsible for approving concrete and hot mix asphalt mix designs, you submit all mix design information to the CDOT project manager.

A CDOT Form 43: Job Mix Formula will be issued by the region materials engineer.

Asphalt content correlation samples
When CDOT performs the independent assurance test, you are responsible for submitting hot mix asphalt content correlation or ignition oven correction samples to the CDOT region materials laboratory prior to placement of hot mix asphalt on the project. This submittal must be a minimum of one week before placement of hot mix asphalt. The asphalt content correlation or correction samples are necessary for assurance tests as well as laboratory check tests.

LPA approves COCs and CTRs
If the COCs and/or CTRs meet the requirements, you approve them.

Once the document has been approved, the material or product is incorporated into the project and the documentation is placed in the materials binders and recorded in CDOT Form 250. If a consultant testing firm is used, CDOT Form 250 is required to be electronically sealed by a PE employed by the testing firm.

Colorado: The Official State Web Portal