Wet 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.


Materials shall meet the requirements of Section 2419.  All aggregates, cement, mineral and liquid chemical admixtures shall be from an approved source and shall comply with the Iowa DOT Standard Specification requirements. Coarse aggregate durability shall be a minimum of Class 2.


All reinforcing steel and iron products and coatings shall meet the requirements of IM 107.


Source approval shall be on the basis of 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 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, per year.


2.   Sample size shall be a minimum of three sets of three cylinders cast using the mix design. Three cylinders will be broken at 7, 14, and 28 days.


3.   Air content, slump and water cement ratio shall be recorded at the time the cylinders are cast.


C.  Compression Testing – A minimum of one set of three cylinders will be made per week of production and tested to determine compliance with the specified strength. At the Engineer’s discretion cores may be taken from finished units to evaluate specification requirements.


D.  Air content and slump shall be tested and recorded at least once per day during production.




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).


The producer of certified concrete segmental 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 and meet the Buy America requirements as described in IM 107 for all steel, iron products and coatings."




Authorized Signature & Date


One copy of the above-described document 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