For a segmental retaining wall to be properly reinforced, grid placement is key.
The first layer of geogrid should be placed on top of the base course of block. This way the geogrid starts at the bottom of the wall where the most pressure exists. Beyond this point, 2 course spacing or 16 in (40 cm) maximum spacing provides the best overall performance of the reinforced structure.
Some applications, including tall walls, might require single course spacing for part or all of the wall height. (ref. BP, Chapter 2.10 & 11)
Allan Block is working to achieve our industry initiative of Zero Wall Failures. With our Best Practices Manual and experience in the industry we are trying to expand the knowledge base for the design of segmental retaining walls (SRW's) by communicating and educating the professionals in the industry. To see the full Best Practices Manual, visit allanblock.com to download today and keep an eye out for more industry Best Practice recommendations here.