Rain Damage at Top of Augured CIP Pile. 10

[KootK]

PARAMETERS

- Helping out with a field issue on someone else's design.

- Augured CIP piers for a pickleball screen wall fence thing. Seriously. Part solid, part chain link.

- Contractor allowed heavy rain to fall on the tops of the piers 60 min after casting.

- Ridiculously windy location. It's small scale but not as small as you might think.

- The owner is a municipality and they are traditionally quite concerned about durability.

- The posts supported on the CIP piers cannot be relocated without causing great pain.

- While I can think of several structurally acceptable solutions, I don't want to get too ridiculous with a damn pickleball fence. I'm a traditional tennis guy and generally annoyed by the pickleball striping on my local courts. Why can't the elderly just play Canasta like they used to?

QUESTION: What's to be done?

SOLUTIONS I'VE CONSIDERED

1) Current favorite. Chip the piers down to the bottom of the anchor bolts. Fill the hole back up with concrete and call it good. This probably does not rigorously deal with durability or anchorage but kind of feels "reasonable" to me.

2) Pull the piles out vertically somehow, augur bigger holes at the same location, and put the piles back. Expensive.

3) Install new piers located away from the posts and install a grade beam ring on the piers such that the superstructure posts can stay where they have to. Expensive. This does kind of feel like an excellent mechanical solution to me however.

4) Excavate the piles and come back with some kind of retaining structure:

a) Sonotube in engineered fill.

b) Sonotube on footing.

c) Retaining wall.

All crazy expensive.

 

[structSU10]

Does it make any sense to sound concrete and if it is bad start chipping. if the concrete is compromised for a few inches stop there and place a repair mortar. If the depth compromises the required embedment of the anchor rods ignoring the repaired topping depth you could cut them low so they get buried in the repair and place new epoxy anchors with the group rotated 45 degrees if the round post can still accept the rest of the fence if that pattern were twisted.

 

[BridgeSmith]

maybe via hydro demolition of the soft stuff etc.

That's a good option, if you have a contractor with the equipment close by. It's becoming more common, but it's still specialty work and equipment, so the mobilization cost could be high.

Colleagues expressed concern that the rain probably penetrated some distance through the soil around the pile, possibly messing with the concrete lower down. I found that moderately convincing.

I wouldn't worry about that. We have contractors place drilled shafts where there's water in the bottom of the hole when they start, and they just keep the tremie in the concrete as they go, and the water gets forced to the top and floods the ground.

My only concern would be the lack of strength and resistance to freeze/thaw damage of the top surface, which could result in scaling or spalling, making it look like crap. If it were me, I'd pitch cleaning it with a pressure washer, and applying an epoxy sealer. We use it for overlays on bridge decks all the time. If it's durable enough for 10 years of trucks traffic, it should work fine for this.

 

[JLNJ]

So, it's a fence post? Unless you can pock up the surface of the concrete with a ball peen hammer, I'd be inclined to leave it. And even if the top concrete is a little compromised your anchors are still in the good stuff.

I totally sympathize with you that once it's brought up you are almost obligated to do something.

I see more and more of this all the time. The GC or the Owner's Rep sees something which may or may not be up to snuff and they want us to assure everyone that it will be OK. It puts us in a tough spot. If you say "fix it", the contractor says "prove that it doesn't meet spec and let's get the lawyers involved" or "I'll fix it but you will need to explain to the Owner why he has to spend the $$ for my change order". If you say "leave it" you might be taking responsibility for someone else's crap work.

 

[jerseyshore]

I wouldn't be too concerned with look because won't these be covered with the court base layers? You'll never see this concrete or anchor bolts, just the post sticking up from the floor.

But I do agree with the tough spot of doing something vs not.

 

[dauwerda]

I'm in the camp of get cleaned off and inspected, but most likely do nothing. Tell them durability has not been compromised (pending testing recommended above), if aesthetics of the top layer is an issue, that is a separate issue - not an engineering issue.

 

[Eng16080]

This might not be possible/reasonable, but:
Could you test the connection by installing the fence post and somehow applying the design load(s) to it (including a factor of safety)?

In general, I've gotta imagine this sort of thing happens all the time. The contractor doesn't say anything about it and nobody else happens to notice.

 

[KootK]

This is resolved now. I'm just dipping back in to provide follow up. Thanks to all for your help.

The municipality is insisting on testing by the geotechnical engineer. I'll report back if anything interesting comes of that.

I had a very unproductive conversation about this with the contractor. He was so focused on avoiding any costs to his company that we were unable to discuss possible, contractor friendly solutions in any meaningful way. The fellow even thinks that my firm ought to cover the cost of any required testing as part of our quality assurance contract. Obviously, that's unlikely to play out that way.

So, it's a fence post?

Yeah, pretty much. It's a fence post with two geotechical engineers on the project no less. That said, it's tall, partly solid, and located in a place where the winds are often nutso. I'm scared to even ride my road bike there. Take a sip of water and a rogue gust will turn your wheel and throw you into a ditch or under a freight truck. Also, while the scale of the loads here is small, so is the scale of the anchorage that was detailed. In some ways, it is inaccurate to assume that the thing is not working hard at the top of the pier. The anchorage is right sized so to speak. Or so the designer of it tells me.

I wouldn't be too concerned with look because won't these be covered with the court base layers?

Just so: covered by the base layer.

 

[SwinnyGG]

So what was the final solution?

I have to be honest, I can't imagine the actual strength of the fence posts is in any way compromised if the concrete had a full hour to set prior to rain starting. I think the whole situation is a little over the top.

 

[KootK]

So what was the final solution?

The municipality is insisting on testing by the geotechnical engineer. I'll report back if anything interesting comes of that.

 

[SwinnyGG]

Apologies Koot.

Testing of what, exactly? The concrete?

 

[GeorgeTheCivilEngineer]

Think I'd have jacked up the baseplate an extra 25mm and flooded the underside with non-shrink grout. This would have filled any surface level holes and protected the underlying concrete.

 

[KootK]

Apologies Koot.

Think nothing of it.

Testing of what, exactly? The concrete?

Yes, the concrete. What kind of testing that will be I don't yet know. It's in the geotech's court, presently, to be the arbiter of what is required to pass the thing.

 

[WinelandV]

It's a fence post with two geotechical engineers on the project no less.

Emphasis mine - how does such a thing happen?

Please note that is a "v" (as in Violin) not a "y".

 

[KootK]

Emphasis mine - how does such a thing happen?

Bureaucracy? I guess one is the normal Geotech and the other is a separate, QA Geotech? I was pretty happy to hand this back to it's Civil PM and not ask to many questions.

 

[milkshakelake]

I know this is resolved now, so this is a retrospective comment. But I have to chime in with how LRFD is overdesigned by design by a factor of a sigma or two, 2500 psi concrete works well, concrete hardens after 28 days, you don't need to sound the top 2 inches because anchor bolts can take moment, and anchor bolts have safety factors upon safety factors. We know that, but as JNLJ pointed out, you have to do something once it's pointed out. If you don't, your friend can be accused of overdesigning, which they did, but correctly. It's a tricky world out there.