Bentonite Plugs

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Author Message J. Peter Jordan Senior Member Username: jpjordan Post Number: 731 Registered: 05-2004 Posted on Wednesday, May 21, 2014 - 04:15 pm:    Had a very interesting discussion earlier this afternoon about need "bentonite plugs" at utility trenches which carry piped utilities from outside the building line to locations in the building line. Because of the nature of our clay soils (silty, sandy, clayey gumbo), they are quite expansive. When utilities are piped in trenches, they rest on an aggregate bed and then are backfilled. This aggregate bedding course becomes a course for water which infiltrates under the building slab and causes heaving in slab on grade conditions. Although I have run into this requirement before, albeit infrequently, this is the first time anyone has given me a good reason for doing it. The bentonite plug consists of a bedding layer of bentonite and then a backfill with bentonite to surround and seal the pipe against water being conducted under the building. I would expect to find this in an MEP spec or drawing, but would like to see it inserted as a standard provision for an Earthwork master specification section. Anyone else out there run into this issue? Nathan Woods, CSI, CCCA, LEED AP Senior Member Username: nwoods Post Number: 582 Registered: 08-2005 Posted on Wednesday, May 21, 2014 - 04:36 pm:    I typically use something like LinkSeal around the penetration instead of bentonite and Xypex in the concrete, but yes, we almost always have something in place. J. Peter Jordan Senior Member Username: jpjordan Post Number: 732 Registered: 05-2004 Posted on Wednesday, May 21, 2014 - 09:02 pm:    No penetration. Trench goes under grade beam.