All thread rod as rebar

[Baldbigears]

If the rebar is plated you may want to check with a true authority.

Before retiring I installed light poles and sign structures on highways. DOT Will not allow coating on any rebar or anchor bolts that go in concrete. The 3" x 16' anchor bolts for very tall poles was only galvanized from top of concrete line upward including the threads for the nuts. We were told something like the galvanized would cause corrosion of the anchors in the concrete and render it dangerous.

 

[Gord Baker]

At present there seems to be no agreement on the use of Hot-Dipped Galvanized Rebar in Concrete. Some say yes, some say no. I say if you have it use it, if not use the cheaper bare rebar.
How long will galvanized steel last in concrete?


"There is typically not a problem with galvanized surfaces in contact with concrete for many decades. There may be some reactions between the galvanized steel and the concrete during the curing stages if there is an absence of chromate either in the concrete itself or on the galvanized steel.

 

[aircommuter]

I also installed numerous anchor bolts for city and county lights and they required HD galvanizing. They all have their own ideas.

 

[jigs_n_fixtures]

At present there seems to be no agreement on the use of Hot-Dipped Galvanized Rebar in Concrete. Some say yes, some say no. I say if you have it use it, if not use the cheaper bare rebar.
How long will galvanized steel last in concrete?


"There is typically not a problem with galvanized surfaces in contact with concrete for many decades. There may be some reactions between the galvanized steel and the concrete during the curing stages if there is an absence of chromate either in the concrete itself or on the galvanized steel.

The current "best practice" is to avoid galvanizing, if any part is exposed. Because any nicks become focus points for the corrosion. Steel with good embedment, usually won't corrode, because the environment in the concrete has too high of a pH level to allow red rust to form. And, the corrosion is a dense black form, similar to Parkerizing, or bluing of firearms.

 

[Gord Baker]

The current "best practice" is to avoid galvanizing, if any part is exposed. Because any nicks become focus points for the corrosion. Steel with good embedment, usually won't corrode, because the environment in the concrete has too high of a pH level to allow red rust to form. And, the corrosion is a dense black form, similar to Parkerizing, or bluing of firearms.

The reason Concrete bridge supports, decks, Parking garages with concrete floors etc., are spalling off is due to the Rusting ReBars which have their iron oxide expanding the area and cracking the concrete. Very evident in any Bridge/Abutment in the Salt Belt. I have worked on deteriorating Parking Garages and the fix was sandblasting the exposed rebar after chipping off loose concrete and epoxy coating it. Some Bridges have a form of Cathodic Protection to keep rebar from corroding so quickly. Google it.

 

[yanmars]

Just as an update, I used some standard rebar but most was fiberglass rebar. I kept the all thread rod for other things.

 

[chim]

A little late to the game, but we poured literally hundreds of bases for site lighting poles where I worked. Poles were anywhere from 12 to 40 feet tall (except for football fields) and IIRC, all the anchor bolts supplied by the pole manufacturers were genuine hot dip galvanized. They weren't plated with shiny cadmium.

 

[MRTOES]

Rusting of rebar is a big problem in some concrete if ever exposed. Don't know how threaded rod rusts in comparison...Don't use it on a hanging patio fifty feet up for sure.

 

[chim]

Specs for reinforced concrete provide minimum embedment depth from the surface to address spalling caused by rust-jacking.

 

[jigs_n_fixtures]

Specs for reinforced concrete provide minimum embedment depth from the surface to address spalling caused by rust-jacking.

But, no matter of how deep you embed the bar, the chlorides will penetrate far enough that it willl corrode. Which is why for bridges and similar structures, the recommendation is to use epoxy coated, or pultruded synthetic bar. And I think they are starting to recommend against using the epoxied steel. And I have gotten plans and spec sets more than once, which were designed to the wrong ACI specification.