Dry cast retaining wall blocks shall meet the requirements of Section 2430 or 2431 of the Standard Specifications and IM 445.




Requests for wall system approval shall be made to Soils Design, Iowa Department of Transportation, 800 Lincoln Way, Ames, Iowa 50010. At a minimum the following information for review.


·      Wall system design manual/procedures;

·      Information about the physical properties of wall system components, unit weights, dimensions of blocks, etc.;

·      Testing/approvals the system has obtained (such as HITEC, freeze-thaw susceptibility reports, etc.);

·      Typical applications of the wall system;

·      Limitations/special requirements of/for the wall system;

·      Case histories of where the system has successfully been used, and

·      Case histories/discussion and analysis where the system has had any failures;

·      Locations/facilities where the wall system components are manufactured;

·      Other additional items…


Wall system approval shall be based on an engineering analysis of the systems design parameters.





Requests for source approval shall be made to the Construction and Materials Bureau, Iowa Department of Transportation, 800 Lincoln Way, Ames, Iowa 50010. Each manufacturing facility shall provide Copies of their Quality Control Plan and Procedures, including testing rates, materials sources and mix designs. Each manufacturing facility shall also supply test reports and documentation to verify compliance with the specified requirements.


Source approval shall be based on an approved mix design and Quality Control Program.





A.     Specimens shall be representative of the whole lot of units. NOTE: The term “lot” refers to any number of concrete masonry units of any configuration or dimension manufactured by the producer using the same materials, concrete mix design, manufacturing process and curing method.


B.   The minimum required sampling rate for mix design approval is as follows:


1.     One sample per mix design per product type (block type) per every three years or when the producer requests a mix design change.  The District Materials Engineer shall receive the test result no later than December 15th of the third year.


2.   Sample size shall be a minimum of eight whole units per mix design. NOTE: Wall units and cap units are considered separate block types.


C.  A minimum of three units shall be sampled and tested per project for comprehensive strength and absorption. These units will be sampled at the producer’s plant and will be used for quality control. Failure to meet the specified requirements may result in the rejection of that lot of units.




Acceptance of blocks shall be based on certification from approved producers using an approved retaining wall system. Approved wall systems and producers are listed in the Materials Approved Products Listing Enterprise (MAPLE).


A certificate of compliance attached to each pallet of blocks shall accompany all blocks shipped and/or submitted for use on Iowa DOT and/or Federal-Aid projects. The producer of certified concrete segmental and modular blocks shall furnish on each shipment day a certified bill of materials or invoice, which identifies the county, project number, contractor’s name and the number of blocks. The certification of compliance shall be signed by a designated or responsible company representative and shall be stated as follows:


The materials itemized in this shipment are certified to be in compliance with the applicable ASTM and the Iowa Department of Transportation Plans, Specifications and IMs.




Authorized Signature & Date


One copy of the above-described documents shall be forwarded to the Project Engineer on the day the item(s) are delivered to the project and one copy shall be sent to the respective District Materials Engineer.


The fabricator shall also provide summary quantity documentation, as shown in Appendix B of IM 445 to the District Materials Office responsible for the project and the project engineer at the completion of the shipments to the project.  A designated or responsible company representative shall sign the certification statement on the summary documentation.


NOTE: Each block manufacturer shall have a special identification mark on each block and cap in a manner approved by the District Materials Engineer to distinguish State-approved blocks from commercial blocks.