Negative Effects of Expansive Clays and the Solution: Structural Load Transfer. Jonathan Culpepper, P.G.

Each year, millions of dollars in damages are the direct result of shrink-swell clay activity. Montmorillonite and other clay minerals within the smectite group are responsible for the extensive cosmetic and structural alterations to the world’s infrastructure. With a 2:1 molecular lattice structure, montmorillonite attracts positive water molecules allowing for expansion, which can exert up to 38.5 PSI of uplift to the supported structures. Shrink-swell clays force the surrounding soils to spatially accommodate for the expansion through consolidating or heaving the adjacent material. Inversely, during seasonal droughts this “accommodation-space” is vacated as the water molecules evaporate and the montmorillonite retracts. Both swelling and shrinking of clay creates immense damage to our homes, businesses, roadways, and various structures. 

The solution to the negative effect of accommodation space is to transfer the load of the structure through the expansive clay layer to a more stable load bearing stratum. This can be accomplished with either a drill-in pier or with helical piers. TMG manufactures a drill-in pier system and various helical pier products that provide support for both pre and post construction applications, which transfers the load to a more desirable load bearing layer. Don’t let the creation of “accommodation-space” destroy your investment and financially cripple you. TMG can supply you or your contractor with foundation support products engineered to combat the effects of montmorillonite and other shrink-swell clays.