Acceptance of asphalt materials will be based on certification from an approved supplier. Asphalt binders will be certified by the Combined State Binder Group’s “Method of Acceptance for Asphalt Binders.” The certification of cutbacks and emulsions will be based on Standard Specification 4138 and 4140 respectively.


A Supplier of asphalt binders is defined as one who produces the final product or who makes the blend or modification that alters the final properties of the Performance Graded Asphalt Binder (PGAB). A Supplier shall be a refinery, a terminal or a Hot Mix Asphalt (HMA) producer. If any modification, blending, or blending of PGAB from different sources is made at the HMA plant, the HMA producer must be the approved supplier and must provide the required certification.


A Supplier of cutbacks and emulsions is defined as a refinery or terminal, which produces the final product. A Contractor diluting emulsion in the field will not be considered a supplier.


Approval shall be secured for each source before materials can be furnished as certified material. Approved sources are listed in Appendixes A and B of this IM.




Applications for source approval shall be made, in writing, to the Office of Materials in Ames. The appropriate District Materials Office will recommend the approval when assured that the supplier has met all qualifications. The Office of Materials will issue a formal approval.


Approval of suppliers will be based on compliance with the following requirements:


A.   Acceptable Control Laboratory


A control laboratory will be considered acceptable if it shows that test results can be obtained within precision limits established by AASHTO for each test. Precision will be judged by comparison with results obtained by the Central Laboratory in Ames or acceptable performance in an approved round robin testing program. Laboratory facilities and procedures may be inspected and reviewed by Highway Division personnel.


Suppliers not participating in an approved round robin testing program shall submit a minimum of two samples of each type of material from regular production to the Central Laboratory in Ames. Complete sample identification and supplier test results for all specified tests must be submitted for each sample. A comparison of the Central Materials Office test results with the suppliers test results will be made.


B.   Acceptable Quality Control Program


The supplier shall submit an outline of the Quality Control Program showing testing frequencies, tests performed, and a typical test report to the Office of Materials. Bi-weekly test results shall be submitted to the Bituminous Engineer via e-mail in Microsoft Excel ® (or equivalent) spreadsheet format. Use a consistent format.


C.   Records & Documentation


A satisfactory program for storage of test reports and shipment records shall be maintained. This program shall enable proper identification and documentation of all shipments made to projects and shall include a file of refinery test reports covering all asphalt binders.


Continued approval of a source will be based on the following:


A.   Ability to consistently supply material meeting specifications


B.    Ability to meet precision limits for testing or has an acceptable performance on round robin testing.


C.  Continuation of originally approved Quality Control Program.


D.  Maintenance of required records


E.   Proper documentation of shipments


Approval to deliver certified material may be withdrawn for inadequate compliance with these requirements.




Monitoring activities of suppliers, including inspection of test reports, quality control records and procedures, and shipping records will be conducted by the appropriate District Materials Office in accordance with Appendices C and D of this IM.


All District Materials Office monitoring activities shall be reported to the Central Materials Office.




Each shipment invoice covering certified materials delivered to a project shall have a signed certification statement as to type and grade, specific gravity or weight per gallon (liter), quantity in load, batch number or other identification, project number, and compliance with the appropriate Iowa Department of Transportation Specifications. A copy of this invoice shall be furnished to the Contracting Authority at the time of delivery.


Delivery tickets for diluted emulsions shall contain the percentage of dilution.


A supplier receiving material shall promptly obtain a report of complete test analysis covering each batch or identifiable lot received.




Properly identified and certified materials may be incorporated into a project. Final acceptance will be based on the certifications and the results of tests on project samples secured in accordance with IM 204 or in accordance with special requirements when specified. Project samples with noncompliant test results may require additional tests.


NOTE: Emulsions, which are to be shipped to Iowa projects, shall be held in storage tanks for a minimum of 24 hours. Certification shall be based on tests made at the time of shipment.