Concrete Crack Repair 3

[DwayneM]

I've been asked to propose a solution to a concrete cracking problem. A pile-supported concrete floodwall, about 9' high, was constructed around a site. To provide a working surface, the contractor had cast a 9" pad along the footprint with no joints. Of course the floodwall has joints at 50' or so, and cracks have formed in the working surface at each joint. I'm looking at how (or whether) to repair the cracks, the main concern is that the occasional water infiltration will allow erosion beneath the wall, especially since the foundation is fairly recent fill.

I'm thinking drill diagonally into the cracks and inject a poly-type sealant. Any thoughts?

 

[Ron]

The cracks are expected. They are probably not wide enough to worry about enough water going through the crack to cause erosion.

Seal the crack with semi-rigid epoxy. It can be injected or the crack can be routed to received the sealant. You don't have to drill diagonally into the crack for injection. It is usually done directly into the crack.

 

[bimr]

The COE states that the base could be sealed with an elastic sealant such as polysulphide elastomer.

U.S. Army Corps of Engineers' Engineer Manual on Retaining and Flood Walls

http://www.mde.state.md.us/programs/Water/DamSafety/TechnicalReferences/Documents/

http://www.mde.state.md.us/assets/document/damsafety/COE/Levees Design Construction.pdf

 

[TGLG]

If water infiltration is a concern, look into using Xypex products.

http://www.xypex.com/

 

[DwayneM]

Thanks guys. Of course, one option is to do nothing, since the cracks are expected, but this is a high importance structure, so longevity is a priority; besides, I expect there to be a bit of movement / expansion / contraction, so the cracks will get worse.

I do think a Xypex product (FCM-80?) or similar sealant would be the way to go - something that would have some flexibility to it, since the slab essentially formed its own expansion joints to mirror those on the wall above.

I'm thinking the procedure would be to cut/rout a groove along the crack, and inject sealant on in there. Fairly simple fix (said the guy who's not in the field doing it).

 

[Ron]

Not so sure I'd go with FCM-80. Too much opportunity to screw up the mixing.

Check some of the Tremco/Vulkem sealants. W.R. Meadows Company makes a very good semi-rigid epoxy ReziWeld

 

[cvg]

Recommend the following reference:

Engineer Manual 1110-2-2502 Engineering and Design, RETAINING AND FLOOD WALLS, Department of the Army, U.S. Army Corps of Engineers

http://140.194.76.129/publications/eng-manuals/em1110-2-2502/toc.htm

the wall should have been designed for both through seepage and underseepage. It should have a seepage cutoff. Waterstops should be installed between the monoliths down to the bottom of the cutoff. Alternatively, a sheet pile cutoff is commonly used. If this "pad" is below the bottom elevation of the cutoff wall, then who cares if it cracks. If it is at the ground surface, you have a big problem...