There has to be a better way 2

[StrucPatholgst]

Precast concrete foundation panels require a continuous bead of polyurethane sealant at each joint, but during assembly if the contractor bumps the open joint with the next panel or slides the next panel in too aggressively, he smears the sealant away. Final step involves beads at inside and outside edges of joints. But polyurethane sealants do not have an infinite life, and most panel installers only warranty the installation for 10 to 15 years, tops. So when the leaks start 10 or 15 years out, the only long-term, non-bandaid solution is to excavate and try to get the joint clean enough for a new bead of sealant to adhere. Even then, you're back to square one with a sealant that has a finite life.

You'd think a better way would be available, but nope. And I wonder what happens 50 years from now when the bolting hardware rusts away from the joints leaking.

 

[JedClampett]

[ol 1]
[li]You fix the caulk after 20 years, or 10 or 15, if you use a one part, cheap sealant. We prefer a two part polyurethane, like Sika 2c.[/li]
[li]You keep an eye on the bolted joints. Hopefully you notice them before they're gone.[/li]
[/ol]

There's no maintenance free buildings. Brick buildings need tuck pointing. Metal needs coating. Wood needs paint. Every building needs new roofs.

 

[phamENG]

Jed - I think his concern is with foundation elements. No maintenance free buildings sure, but it's also not normal to dig up your foundation every 10-15 years.

StrucPatholgst - are you talking about precast basement walls? If so, what about externally applied waterproofing panels like the ones used in CIP or even masonry basement walls? Or some sort of membrane waterproofing.

 

[StrucPatholgst]

phamENG, yes, I was referring to precast basement foundation panels. It's an example of a design trade-off with deferred - but very real - consequences.

 

[phamENG]

I agree. I haven't had to deal with any, but I have looked at a couple of failing masonry basement walls in my area. I'm in coastal VA, so most basements around here are well below the ground water level and are subject to a lot of hydrostatic pressure. So most of them - if they were ever waterproof - are now indoor pools.

The few recent applications I've seen (usually for elevator pits) use either a membrane that gets adhered to the wall or rigid panels or a waterproof panel with asphalt/bitumastic sealant at the seams. Then that gets covered with a drainage board and connected to a sump. Seems like a similar arrangement would be prudent for precast panels. Excavate, pour your base slab, set and attach the panels (detailed with connections on the interior so inspection can occur by removing some drywall/baseboards rather than 9 feet of fill), apply exterior water proofing and drainage setup, back fill and compact.

 

[JedClampett]

Sorry, I saw that but couldn't believe it. We design water containing tanks or basins. A bead of caulk is not water resistant, water proof or water anything. If the intent is to keep a basement dry under any pressure, like groundwater, it's not going to work for long, if at all.

 

[epoxybot]

What about trowel grade bentonite, like Bentoseal? It comes in a pail or sausage tube.

 

[BridgeSmith]

You should look into the butyl rubber joint wrap used for sealing the joints of precast box culvert sections.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[FacEngrPE]

The same problem occurs with rehabilitation of drainage structures. Particularly sewage structures. Lining works for the pipes if they are in reasonable alignment, and still mostly round.
Structures can be lined, but it is necessary to stop all inward water leakage first. As phamENG pointed out when structures are mostly below the waterline, there is hydraulic pressure to contend with.

I have found single part moisture cure urethane grout injected through the structure wall in the area of the leak (sometimes through the leak) is effective. The method is claimed to be long lasting, and avoids digging up the structure.

If the manhole is brick having poor condition mortar joints, it is necessary to repoint or line the manhole with high strength mortar at the same time as the grout is installed.

Helmet Cam: Brick Manhole Curtain Grouting
Similar grouts are available from a number of sources.