Carbon Fiber Foundation Repair
I own a property where the foundation walls show some slight bowing, and there are a few small (1/8 inch) horizontal cracks in the mortor joints between the blocks.
After correcting the gutter, drainage, and grading problems, several solutions for the walls have been suggested.
1 - Do nothing, but keep an eye on it.
2 - Dig out around the foundation, then use a tie rod and two metal plates to straighten and support the foundation.
3 - Install I-beam supports
4- Install carbon fiber bands along the inside wall.
Has anyone used these carbon fiber supports? I would appreciate any feedback anyone has on this as it seems to be a fairly new technology.
I would get recommendations for a structural engineer and get their opinion of the problem. I have used a structural engineer 3 times. For a site inspection it was $250. 2 of the times he told me that there was nothing to worry about. On the third time there was structureal damage and for another $250 he drew up the plans to be submitted to get the permits. Not expensive, puts your mind at ease that you are doing it correctly, and it covers your arse for any possible resale.
Brenda
I am a commercial construction project manager in Texas. On one of my projects the structural engineer designed these carbon fiber reinforcing strips to be installed to the underside of some elevated concrete decks in places where this older structure was in question. I have listed a website with information about this particular product below. I would reccomend that you contact a structural engineer in your area that inspects residential structures and ask him about this product for your application. This product in the 4" wide option cost about $25/lf installed on my project.
Hope this helps.
Sika CarboDur® Carbon Fiber Reinforced Polymer Strip
http://www.cif.org/nominations/nom_283.html
IU am quoting here but this would seem to be areason to not use carbon strips on just one side of a foundation.
"Overlays were most effective when the system was applied directly to the potential crack trajectory. One-sided applications introduced bending and did not significantly improve performance."
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also, the previous posters were mostly from the south...here in the north, 1/8" horizontal cracks are a fact of life ( depending on the age of the building) How old a building are we talking about?
rmdane,
The building was constructed in 77'. I the cracks do only seem to be 1/8 inch, but upon closer inspection, there may have been some cracking earlier. There seems to have been some repair work done on the mortor joints.
The wall seems to be bowing visibly, but only barely. I would estimate that the part of the wall most bowed has moved in about one half inch. I firgured that if there were ever a time to have it reinforced, this might be the time because the walls would not have to be straightened.
It may also be somehting that requires no repair. :-?
I have used the carbon fiber bands . They are great. They are quick to install, inexpensive (compaired to tiebacks) and do not take up all the room that the tie backs use.
I have a license to install and could hook you up with the product. The carbon fiber will increase the bearing capacity of your wall to about 15,000 psf. A regular block wall with just horizontal re-inforcement can only withstand about 4500 psf. Contact ne if you are interested. The carbon fiber will work on walls with up to a 3" bow!!!!
Oh and by the way, The application has been researched by a major testing company and one sided application will solve your problem. I also have a degree in structural engineering and 30+ years in the construction business.
How long have you been using the carbon bands, and how will I know if the bowing in my wall is enough to indicate that I need to take action?
Are you seriously not willing to pay $250 to have an expert actually look at your wall and tell you if it about to blow out?
I understand that a penny saved is a penny earned; but come on; if you have a structural issue, don;'t you think whomever you sell to might also see the problem - wouldn't it be nice to pull out the written report by the engineering co to prove that there is no problem here? Or to identify the best solution for you in case you need to correct the problem.
Feltman, the structural engineer is scheduled for August 13th. As he is employed by a company that specializes in basement wall repair, I felt it important to educate myself on the topic to prevent getting ripped off. Also, if reinforcement is needed, the carbon bands look easy to install.
Your point about being able to show a future buyer a structural engineers report that the walls are structurally sound is well taken.
Feltman, the structural engineer is scheduled for August 13th. As he is employed by a company that sells basement wall repair systems, I felt it important to educate myself on the topic to prevent getting ripped off. Also, if reinforcement is needed, the carbon bands look easy to install.
Your point about being able to show a future buyer a structural engineers report that the walls are structurally sound is well taken.[ Edited by curtbixel on Date 08/01/2004 ]
My structural engineer is self employed, sales no other services, and is not affliated with any products. To hire an engineer that works for a company that does repair compromises his opinion. Like hiring an inspector that also does repair. Unless the house is perfect, he will find something.
Brenda
I agree with Brenda, in her assessment of the "inspector".
HOw tall is this basement wall? IS it an exposed wall that is part of the living area? What effect will the carbon bands have on the esthetic appearance and will they draw attention to the wall?
If the wall was 20' and had a 1/2" bow in the center of it what are you worrying about?
And with all due respect to structural engineers, the studies that I have been able to find mainly have to do with steel reinforcement, I would like to see something showing its use for cinder block. Especially CB that may not be tied in and may only have a mortar set with no interior reinforcement. (this was common for a period of time).
I copied this from the website and you might be able to use this if you persist in carbon fiber repair.
How to Use
Surface Preparation Surface must be clean and sound. It may be dry or damp, but free of standing water and frost. Remove
dust, laitance, grease, curing compounds, impregnations, waxes, foreign particles, disintegrated
materials and other bond inhibiting materials from the surface. Existing uneven surfaces must be filled
with an appropriate repair mortar (e.g. mixed Sikadur 30 epoxy with the addition of 1 part oven-dried
sand). The adhesive strength of the concrete must be verified after surface preparation by random
pull-off testing (ACI 503R) at the discretion of the engineer. Minimum tensile strength, 200 psi (1.4 MPa)
with concrete substrate failure.
Surface Levelness/Irregularities: Maximum allowable deviation in 3 ft. shall be limited to 1/4” (6 mm)
but no greater than 1/8” (3 mm) per foot. Any sharp edges (i.e. fins, form-marks, etc.) must be ground
smooth and flush.
Preparation Work: Concrete - Blast clean, shotblast or use other approved mechanical means to
provide an open roughened texture.
CarboDur - Wipe clean with appropriate cleaner (e.g. MEK).
Cutting the CarboDur Laminate:
Preferred: CarboDur laminates should be cut with tools using a “shearing” force (e.g. guillotine or
heavy duty shears). Care must be taken to support both sides of the CarboDur laminate to avoid
splintering.
Alternate: A hack saw or other abrasive cutting method may be used. However, extra care must be
taken to support the CarboDur laminate on both sides to avoid splintering. In addition, extra care must
be taken to avoid exposure to carbon dust (see Caution).
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