Hey OnBoard and (other design professionals)

[Gil Bang 26119]

Out my way, Oceanside (CA) harbor is undergoing a renovation and some of the concrete docs are being replaced.  The paper says that because the saltwater is so corrosive to metals, the new concrete docs will have fiberglass reinforcement instead of rebar.

I've never heard of this. Tell me about it por favor. 

[Onboard 2.0 9083]

13 minutes ago, Gil Bang said:

Out my way, Oceanside (CA) harbor is undergoing a renovation and some of the concrete docs are being replaced.  The paper says that because the saltwater is so corrosive to metals, the new concrete docs will have fiberglass reinforcement instead of rebar.

I've never heard of this. Tell me about it por favor. 

 Fibermesh concrete, is concrete infused with fiberglass strands in the concrete matrix. We use that for concrete slabs in most residential garage, porches, and basements.  The old way was a 2 x 2 wire mesh was placed in the form then concrete poured in to the form.

I'm guessing this is larger, heavy duty strands of fiberglass, or even some type of sheet good set up in the concrete forms before pouring concrete ?  That's a wild ass guess though on the last part.

[Gil Bang 26119]

goddammit.  Concrete DOCKS not docs.  

 

I've never seen 2x2.  Out here, reinforcement is rebar, or "6-6-10" wire or a combo of both.  6-6-10 is 10 gauge wire welded in a 6" grid pattern. 

Edited August 26, 2018 by Gil Bang

[woohorn 1131]

All I know is fibermesh and fiberglass reinforcement are totes different brah, lol.

[TwiceHorn 31705]

Interesting topic.  Can google around and find some info, https://en.wikipedia.org/wiki/Reinforced_concrete#Fiber-reinforced_concrete

 

It would appear that they are using "fiberglas" or fiber reinforced polymer rods and/or meshes in lieu of steel.  The rods are as strong (tensile) as steel, but not as stiff, so it appears they would have to be considerably larger, or shaped in such a way as to increase stiffness (I-beam or channel or something).  In other words, apparently fine for pre-stressed, where the rods are in tension, but not so good for bending/shear loads when the rods aren't pre-stressed or using a mesh.

 

Oddly relevant for you, Gil, apparently an early use was in medical buildings housing MRIs where they didn't want all the ferrous metal around.

Edited August 26, 2018 by TwiceHorn

[Onboard 2.0 9083]

18 minutes ago, Gil Bang said:

goddammit.  Concrete DOCKS not docs.  

 

I've never seen 2x2.  Out here, reinforcement is rebar, or "6-6-10" wire or a combo of both.  6-6-10 is 10 gauge wire welded in a 6" grid pattern. 

Yeah Not sure what I was thinking 6 X 6 X 10. Stopped using it a few years back, when the contractors all started whining  about cost and how fibermesh was so much easier to place.   

[Onboard 2.0 9083]

4 minutes ago, TwiceHorn said:

Interesting topic.  Can google around and find some info, https://en.wikipedia.org/wiki/Reinforced_concrete#Fiber-reinforced_concrete

 

It would appear that they are using "fiberglas" or fiber reinforced polymer rods and/or meshes in lieu of steel.  The rods are as strong (tensile) as steel, but not as stiff, so it appears they would have to be considerably larger, or shaped in such a way as to increase stiffness (I-beam or channel or something).  In other words, apparently fine for pre-stressed, where the rods are in tension, but not so good for bending/shear loads when the rods aren't pre-stressed or using a mesh.

This was my concern as well. Fiberglass strength, over time there would seem to be more movement because of the lower stiffness. Water constantly moving back and forth would seem to be a factor.

[Gil Bang 26119]

3 hours ago, TwiceHorn said:

Interesting topic.  Can google around and find some info, https://en.wikipedia.org/wiki/Reinforced_concrete#Fiber-reinforced_concrete

 

It would appear that they are using "fiberglas" or fiber reinforced polymer rods and/or meshes in lieu of steel.  The rods are as strong (tensile) as steel, but not as stiff, so it appears they would have to be considerably larger, or shaped in such a way as to increase stiffness (I-beam or channel or something).  In other words, apparently fine for pre-stressed, where the rods are in tension, but not so good for bending/shear loads when the rods aren't pre-stressed or using a mesh.

 

Oddly relevant for you, Gil, apparently an early use was in medical buildings housing MRIs where they didn't want all the ferrous metal around.

Thanks for that, it's quite interesting.  

Last MRI I was involved with was an Aurora 1.4 that my kinda-sorta clients purchased.  They were a breast specialty practice in O.C...a surgeon and a radiologist that had teamed up. The total invoice was 1,400,000 give or take a few bucks.  The room where the MRI was installed was completely lined with a fine copper mesh.  Floor, walls, and ceiling.  Our super-deluxe ASC was on the ground floor, their center was on the 2nd.   The MRI was directly above our waiting room, and the "womp womp" of the operating MRI was noticeable to the point of being mildly annoying.  I say "kinda sorta" because the surgeon was a member of our ASC, although her practice was separate and distinct.  As the finance guy in our LLC, I had tried (and failed) as a courtesy,  to help them get some financing for their de novo practice using our usual sources...somebody else succeeded where I had failed. 

We all went in as original tenants in a medical office building, and I was familiar with the structural plans, and there was no fiberglass in this mofo...only red iron.  

Our ASC was designed by our go-to  architect, a guy that did 100% medical.  The Breast Center was designed by a big, successful SoCal architecture firm that only dabbled in medical.  
 

Our architect, on a routine site visit was inspecting the exterior of this particular 5 floor building and noticed the quench bleed tube was directed at a sidewalk below.  He had to inform the other architect, quite awkwardly, that in the event of a magnet failure, the poor bastard smoking a cigarette on the sidewalk below would find himself frozen solid instantly.  

The conversation got heated, but the other eventually guy did a redesign of the quench system. 

The building department didn't catch it because they didn't know a MRI from a GFI.  Our ASC was  inspected by California OSHPD.  Those mofos know medical cold. 

 

[Bevo 13659]

There are a lot of new materials available or soon to be available as replacements for rebar (graphite, carbon, and fiberglass). Here is a decent article on it.

https://www.compositesworld.com/articles/a-hidden-revolution-frp-rebar-gains-strength

I was curious about different materials because I am building a saltwater pool. It seemed to me that rebar would be a poor material because of corrosion and electrical transmission and because forming with it would seem slightly difficult (although bending rebar seems pretty easy when the professionals do it). Anyway, my research was a waste of time because subcontractors know nothing about alternative materials and how to install them and me explaining it to them in Spanish is less than ideal. It is much easier for them to just stick with what they know.

[Onboard 2.0 9083]

12 minutes ago, Bevo said:

There are a lot of new materials available or soon to be available as replacements for rebar (graphite, carbon, and fiberglass). Here is a decent article on it.

https://www.compositesworld.com/articles/a-hidden-revolution-frp-rebar-gains-strength

I was curious about different materials because I am building a saltwater pool. It seemed to me that rebar would be a poor material because of corrosion and electrical transmission and because forming with it would seem slightly difficult (although bending rebar seems pretty easy when the professionals do it). Anyway, my research was a waste of time because subcontractors know nothing about alternative materials and how to install them and me explaining it to them in Spanish is less than ideal. It is much easier for them to just stick with what they know.

Yep, new materials only work when the installer knows what he's doing with that new material, and understands the subtle little things you need to do to ensure a successful install.

My golden rule is I never use a new material (especially exterior materials) unless its been actually field tested a min. of 10 years (SEE:  faux slate roofing shingles).

 

The new rage for pools seems to be ion filtered pools. Easier than salt water pools to maintain apparently.

Edited August 26, 2018 by Onboard 2.0

[BottleRocket 647]

I was on a project in the 90’s that used fiberglass rebar and fiber reinforced concrete to build a two story anechoic chamber that was completely RF shielded. The facility was for USAF guided weapons systems testing at Eglin. The fibers stuck up from the slab like a porcupine and had to be burned off with a roofing torch. Low tech meet high tech.

I believe clean room construction has been using fiberglass rebar for a long time too.