Engineering Fabric shall meet the applicable requirements given in the Standard Specifications.


Engineering Fabric Forms shall meet the requirements of the current DS titled “Fabric Formed Concrete Structure Revetment”.


Approved products are listed in MAPLE.



For products with label or identification, acceptance of Engineering Fabric and Fabric Forms for use on Iowa Department of Transportation projects is based on manufacturer and brand name approval. Approved manufacturers and products are listed in the Materials Approved Products Listing Enterprise (MAPLE).


For products without label or identification, acceptance of Engineering Fabric and Fabric Forms for use on Iowa Department of Transportation projects is based on a statement of certification:


                                                Certification Statement


This is to certify that (insert manufacturer name, product name) this Engineering Fabric or Fabric Form meets the requirements of the (insert applicable specifications article) of the Iowa Department of Transportation.





Authorized Signature & Date


A responsible company representative shall sign the certification statement.




To obtain approval, the manufacturer shall submit the following to the Construction and Materials Bureau:


1.   Product Identification

2.   Technical information on the use of the product

3.   Quality control procedures that indicate product uniformity is reasonably assured

4.   Approximately a 1 square yard sample

5.   NTPEP (National Transportation Product Evaluation Program) test results for all classes of Engineering Fabrics. If NTPEP test data is not available for Triaxial Polymer Grid, then independent lab test data results may be submitted for review.

6.   Products which have been tested by NTPEP and meet the requirements of Iowa DOT Specification for the class of product may be approved after receiving NTPEP test results.

7.   In the case of silt fence, after receiving the NTPEP test data for the fabric, the cord / band and the full silt fence assembly may be tested to see if it meets Iowa DOT specifications.

8.   In the event that a firm is selling their products under private label agreement with another manufacturer, the private label firm shall submit an application identifying the original product designation and a letter of certification from the primary manufacturer verifying the information.

9.   Approval of Engineering Fabric Forms will be based on satisfactory evaluation of a preliminary sample.


To maintain approval of products within MAPLE, Manufacturing facilities of all engineering fabric classes must submit their product and facilities into the appropriate NTPEP Audit program and secure and maintain a successful audit thru NTPEP for their facility in accordance with the appropriate workplan (GTX, REGEO, SSGEO) within NTPEP. If a product does not fall into an existing NTPEP workplan, independent laboratory testing and Quality Control procedures shall be submitted to the Construction and Materials Bureau yearly if the product has changed in any regard.



The Construction and Materials Bureau may request sampling and testing of Engineering Fabric and Fabric Form for the purpose of monitoring the approval program at any time.