Corrosion protection strategies for rebar anchored to bedrock

[skeletron]

I'm trying to brainstorm some different ways to accomplish corrosion protection for rebar anchored to bedrock. The site is located near a lake (not necessarily ocean water).

Epoxy-coated rebar
Stainless steel rebar
Grouted systems (Dywidag)
Grounding the rebar

I would like to read if there other methods or successful experiences using a certain method.

 

[bugbus]

I have done similar with post-tensioned rock anchors, installed vertically through existing bridge piers and into underlying rock for strengthening purposes.

These were Dywidag bars pre-grouted in the factory in corrugated plastic sheaths, and then the whole assembly grouted again into a cored hole in the rock (sandstone, near fresh water source).

That level of protection is a minimum requirement from the road authority where I am.

 

[dik]

Can you use HDG?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Ingenuity]

I have used HDG rebar but prefer what the PTI does for rock anchors and use “double corrosion protection” (DCP) - HDPE corrugated sleeve and grout, as per gusmurr’s experience. Such would require large diameter holes.

Soil nail component manufacturers often cite 50 years of corrosion protection based upon galvanized elements, depending on the environment.

 

[STrctPono]

We too either use Dywidag or Williams Form epoxy coated all-thread bar pregrouted in an HDPE sleeve. 9 times out of 10 it is an 8" dia. hole but sometimes 6" dia.

It is possible to get them to add corrosion inhibitors into the pregrout. I've been through this exercise many times. They typically always either grumble or omit it in the first round of shop drawings but they can if it's in the contract documents.

The only time I have ever not used a pregrouted bar system was when we had custom 2205 stainless steel anchors made. We still grouted these in an 8" hole however.

I suppose the answer to your problem really is dictated by your specific site conditions. A marine condition or nearby potash mine might push me to the stainless steel option but even high sulfate levels or being constantly immersed below ground water levels would make me think that the pregrouted sleeve option is the way to go and I would additionally consider epoxy coating that bar and adding corrosion inhibitors to the mix.

 

[skeletron]

It's for a residential application and a lakeside property. While it may not require the full nine yards like a commercial or industrial build, I believe it does deserve some consideration with cost in mind.

It seems like most people are suggesting a coated bar and then a grouted hole...almost giving two layers of protection...which seems in line with some other advice I was given.

 

[STrctPono]

Is this a micropile compression element?

 

[skeletron]

No. Not a micropile compression element in this situation. Tying down a footing and providing sliding resistance.

 

[hokie66]

I have used HDG reinforcing bars, grouted into a decent size hole. The other solutions sound interesting.

 

[Settingsun]

Epoxy grout is almost impermeable and provides good protection.