| Pages:
1
2 |
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
rusty rebar
I never hear about any cathodic protection installation for all the varrilla (rebar) used in building homes/resorts. I do hear about the rusty
varrilla (rebar) that is used. Salts and heat increase the corrosion process and spalling of concrete due to the expansion of the metal rebar as it
corrodes can wreck the structural integrity of a building. a few hundered bucks and some dilligence in insuring there is electrical continuity of the
rebar would minimalize this corrosion. i guess most folks don't even know.
|
|
|
J.P.
Super Nomad
Posts: 1673
Registered: 7-8-2010
Location: Punta Banda
Member Is Offline
Mood: Easy Does It
|
|
Rebar
After a lifetime of installing Rebar in all kind's of structures that's the first I ever heard of that . I Do know without Rebar most structures would
have little or no integrity.
Because of the Salt used on the highways the rebar failed much earlier. The solution for that kind of failure was they tore the bridges out and
rebuilt then using Teflon coated rebar
|
|
|
Islandbuilder
Senior Nomad
Posts: 555
Registered: 11-9-2011
Location: nob
Member Is Offline
Mood: bewildered
|
|
The International Building Code require the use of clean re-bar. I have bonded re-bar to use it in place of driven ground rods for electrical panels,
but never heard of it needing to be bonded to protect it from electrolysis.
In fact, unless you used a sacrificial anode (a zinc) bonding would just insure that the whole steel armature would rot out.
The new sealed re-bar protects against rust, not electrolysis.
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
Point made (never heard about it). Many structures built without CP (cathodic protection) have had to be retrofitted with anodes to mitigate some of
the effects of this corrosion after the fact. Non continuity of the rebar inside the concrete minimizes the universal effect of these installations,
and only localized protection is acieved. The rebar areas that are in contact with the anodes.
fusion bonded epoxy coated rebar helps by elininating exposure of the metel to the elements, but no coating is perfect, dings in coating, material
defects, etc.making the rebar contiuos electrically, and adding CP mitigates these minor flaws in coating by providing a sacraficial anode to deplete
before the steel will.
|
|
|
Islandbuilder
Senior Nomad
Posts: 555
Registered: 11-9-2011
Location: nob
Member Is Offline
Mood: bewildered
|
|
Wow. Good info bledito. That means that most of the concrete foundations in the world are just ticking time bombs.
I'm glad I'm old!
I see the epoxy coated stuff going into state and federal projects, but so far not in light commercial and residential. Perhaps a change in the codes
is coming?
To meet codes there is (was? I've been out of construction for almost 10 years now) a 20x diameter overlap secured with at least 3 ties was required.
The union of vertical and horizontal runs had to be secured before the pour, not dug into the mud and "hooked" like we used to do it.
So, not bonded, but all steel in contact.
How does the cathodic protection work? An accessible anode tied into the steel? Doesn't it all need to be wet (and salty) to have molecular erosion?
Thanks for the new info, appreciate it! (even if it does scare the crap out of me!)
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
concrete never fully cures, moisture is present. infiltration from rain, run off and the atmosphere can and will penetrate. Not looking to cause
anyone to crap themselves. It's just the nature of the beast, metal will alway want to revert to its original state ore. and yes a accesable
sacraficial anode, magnesium is less expensive,, can be dropped into your septic system providing activation of the anode. and bonded via copper wire
to the rebar. this should work. a multi meter on dc volts should read above -.85v when attached to the wire and using a copper sulfate referance cell
to obtain the reading.
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
rust never sleeps, they wrote a song, I think it was neil young. it will take a long time but eventually it will cause failures.
|
|
|
woody with a view
PITA Nomad
Posts: 15939
Registered: 11-8-2004
Location: Looking at the Coronado Islands
Member Is Offline
Mood: Everchangin'
|
|
after our lifetimes, mostly. i can't vouch for the below the border work methods buts up north we're talking lifetimes if the correct material
(coatings) and methods of installation are followed. nothing is perfect, concrete will crack and steel rusts.....
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
north of the border things have definatly changed. south not so much. for my future generations i would want to insure structural integryty of the
homes i build. the methods are simple and cp is easily achieved for minemal cost 17# magnesium anode could last 30+ years till it needs replacing.
an egg crate structure with deteriorated rebar inside it is not going to be structurally sound 50 60 years from now look at all the bridges and roads
we're now completely replacing because this wasn't considered or known 60 years ago.
|
|
|
DavidE
Ultra Nomad
Posts: 3814
Registered: 12-1-2003
Location: Baja California México
Member Is Offline
Mood: 'At home we demand facts and get them. In Mexico one subsists on rumor and never demands anything.' Charles Flandrau,
|
|
When I poured a patio slab 50' from crashing tropic waves I had ground up five dollars some odd cents worth of pennies and put them in a zip-loc. When
the pour reached the varilla, I P-nched off the zinc a bit at a time and dusted along the rods. Better than bare steel I guess. i brought the pennies
down to melt and hot dip galvanize reinforcing brackets for the patio wood railing. Pickled the metal in muriatic acid and then let cool. I had to go
to three banks to get 20 dollars worth of zinc. Who knows if the zinc dust worked...the brackets resisted corrosion wonderfully.
A Lot To See And A Lot To Do
|
|
|
TMW
Select Nomad
Posts: 10659
Registered: 9-1-2003
Location: Bakersfield, CA
Member Is Offline
|
|
Sometimes on Sunday morning I turn on Science Fantastic on the radio. One time they talked about the buildings and bridges in Rome and why they have
lasted for a couple thousand years. The rebar they used was not steel. It may have been copper or an alloy of some kind I don't remember. They went on
to say that the concrete buildings built in the past couple of hundred used steel rebar that rusted and usually had a life span of 50 -100 years. In
the last 20-30 years or so that has changed to using treated rebar to prevent the rust or to use a non-steel rebar.
I've always wondered why they always want to tear down a stadium and build a new one. Now I know.
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
http://www.frpdistributors.com/gfrp-vs-steel/gfrp-vs-galvini...
here a link to what happens
|
|
|
bajagrouper
Senior Nomad
Posts: 964
Registered: 8-28-2003
Location: Rincon de Guayabitos, Nayarit, Mexico
Member Is Offline
Mood: happy and retired
|
|
I guess using salty beach sand mixed into the cement doesn't help either......
I hear the whales song
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
it won't help stop the corrosion but it will probabally kill the METAL EATING MICROBES.
|
|
|
Ateo
Elite Nomad
Posts: 5898
Registered: 7-18-2011
Member Is Offline
|
|
Interesting. No different than old Underground Storage Tanks (UST's) storing motor vehicle fueling.
Old tanks were steel and would corrode and leak. So they started using Cathodic Protection or Sacrificial Anodes to negate the effects of corrosion.
But a house won't leak and contaminate the soil. I guess it'll just fall over in an earthquake.
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
what about the problems with mismatched metals in the rivets on airplanes ?
|
|
|
woody with a view
PITA Nomad
Posts: 15939
Registered: 11-8-2004
Location: Looking at the Coronado Islands
Member Is Offline
Mood: Everchangin'
|
|
aluminum rivets in aluminum airplanes?
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
with steel shanks oh my oh my.
|
|
|
woody with a view
PITA Nomad
Posts: 15939
Registered: 11-8-2004
Location: Looking at the Coronado Islands
Member Is Offline
Mood: Everchangin'
|
|
if it was an issue they'd use a steel rivet on the steel shank. how many planes have fallen out of the sky due to dissimilar rivets/metals?
|
|
|
bledito
Nomad
Posts: 420
Registered: 7-6-2013
Member Is Offline
|
|
http://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243 only 1 or 2 so far
|
|
|
| Pages:
1
2 |
![[*]](images/xmbforum/default_icon.gif){kind=icon}
