From the GMA Techline
RE: MSE wall connection?
When an MSE (mechanically-stabilized earth) wall is constructed using geosynthetic reinforcement, how is it connected to precast concrete facing? Are metal tabs cast in the concrete or can a geosynthetic product be cast in the precast panel?
If this connection is always metal, does the backfill need to be tested for resistivity, sulfates, and chlorides as it would if a metallic reinforcement was used?
(Brian | California)
Reply: Thanks for your question, which is a logical one to ask. The connection of geosynthetic reinforcement (geogrids or geotextiles) can be either mechanical or frictional. Let me explain each of them.
Mechanical connections can be made in a variety of ways depending mainly on the type of wall facing. For masonry blocks (also called segmental retaining walls) “keepers” can be inserted thereby fastening the reinforcement mechanically. There are other configurations, depending on the block type, as well. For concrete panels, metal or polymer inserts can be cast in them, whereby the reinforcement is connected to the inserts during construction. For both situations, the reinforcement must be matted to the attachment system—i.e., no swapping geogrids at the last minute!
Frictional connections have great versatility in that the geogrid or geotextile reinforcement is merely sandwiched between the lower and upper facing elements. This can be done with masonry blocks, steel wire brackets, gabion baskets, etc. Of course the length of embedment is critical, but that is a design issue.
Brian, you might go to the various MSE manufacturers and vendors since their websites are generally clear and educational in this important aspect of MSE walls, berms, and slopes.