basalt fiber?

Discussion in 'Composites' started by PMD, Dec 3, 2017.

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  1. Dec 3, 2017 #1

    PMD

    PMD

    PMD

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    Have been around aviation for decades, but more on the periphery of homebuilts, so forgive me if I am discussing something that is either common knowledge or already disgussed. BTW: I did try a search here.

    In another world, my passion is to eliminate steel as a re-inforcement in concrete (at least steel as a bar). The absolute best solution is to make carbon fiber bar, but you can guess the cost issues involved. The second best choice - and not that far away in values for carbon - is basalt. Basalt fiber has been around for a while, but lately production methods have managed to drop the price a bit. There is one concrete rebar manufacturer that uses it now - has been accepted under the same approvals as for glass fiber, but is far stronger material and much more chemically inert.

    The aviation question came as a result of someone asking me about the properties of basalt fiber as they wanted to investigate it for manufacture of radomes. I will measure some electrical properties on basalt/epoxy samples, but beyond that, I am not sure where to go or what to suggest to them. Since, let's face it, just about anything "new" in genav was tried and understood first in experimental aircraft, I was hoping there was a bit of knowledge in the composite side of homebuilding. After all: "better" than glass and cheaper than carbon should be something that makes sense in aircraft construction, shouldn't it?
     
  2. Dec 3, 2017 #2

    pictsidhe

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    I love the idea of making aerospace structures from stone. Availability of basalt in the US was poor last I looked, and properties were a bit variable. It is slightly heavier than glass and when I looked, about S-glass in strength. It has good high temperature properties.
     
  3. Dec 4, 2017 #3

    proppastie

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    it is not common knowledge, My suggestion is to talk to the manufacturer, and if he can not give you specifications, I would not think it would be a good idea to use it. You are talking about a research project to determine the specifications, and manufacturing variability. I admire your desire to improve concrete, or develop other structural materials but unless you are a University, or large manufacturer I would think it may not be a practical avenue.
     
  4. Dec 4, 2017 #4

    Victor Bravo

    Victor Bravo

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    Got plenty of Basalt here on the left side of the country. We even have so much of it there is a town named Basalt, NV. We've got great big mountains full of it, and there's dozens of square miles worth of a thick layer of it in the Owens Valley right on top of the surface, over a hundred feet thick in places.


    Basalt.jpg
     
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  5. Dec 4, 2017 #5

    wsimpso1

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    I used the Advanced Search function using Basalt and several threads where this stuff has already been talked about. Might be worth your while to do the same search.

    Billski
     
  6. Dec 15, 2019 #6

    PMD

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    glass does not do particularly well in higher pH chemistry (such as typical cement used in concrete), has great high temp properties and is very stable chemically so will work with pretty much any resin in any kind of composite matrix (cement included).

    The story starts in Ukraine where a particular institute/business left over from USSR days had become very good at drawing basalt fibers. A Russian lady "bought" the business after the fall of the USSR. Of course, China long ago picked up the technology and you can buy fiber, mat, roving and I think chopped fiber (IMHO, one of the neater ways to enhance strength) in commercial grades. Sadly, being NIH (not invented here - but I think it actually was early in the 20th century) there are few standards that apply so it is often treated as "equivalent to glass" in such things as concrete rebar (made by one company in TX in US sizes). I believe its ultimate strength may in fact be quite a bit better than glass.
     
  7. Dec 15, 2019 #7

    proppastie

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    what do they sell this to be used for......if it is a "strength enhancement" how can one use it without specifications...stress analysis requires numbers.
     
  8. Dec 16, 2019 #8

    cheapracer

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    Because they understand the minimum numbers, and that's all you need.

    The issue with Basalt is it's as strong as Carbon Fiber, for one batch, then the next batch is about the same as E'Glass, i.e. inconsistent fibers. Therefore simply design for E'Glass, and you know that you will often be safely above your numbers.

    Got a couple of factories in my area, Basalt reo for concrete mostly, but they sell matting as well.
     
  9. Dec 16, 2019 #9

    proppastie

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    is it less expensive than glass?.....
     
  10. Dec 16, 2019 #10

    pictsidhe

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    Somebody needs to persuade them to test batches. The E-glass batches are sold for rebar. the Carbon grade gets sold at a premium to us. If they make a reasonable amount of high grade stuff, this could be profitable avenue to be explored.
     
  11. Dec 16, 2019 #11

    cheapracer

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    Not sure how you can check individual fibers of millions passing through the factory everyday ....
     
  12. Dec 16, 2019 #12

    trimtab

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    Basalt has interesting properties. I've used it for a range of composite structures to exploit those properties.

    First, the strength is somewhere between E- and S- glass. The comments related to variability are really not relevant here, as manufacturers use a blend of material sources and my tensile stress tests from different lots from two different manufacturers were generally within 7% of lot-to-lot samples and 10% between manufacturers. These tests themselves are difficult to execute and get to within 5% for E- or S-glass by comparison for lot-to-lot, and close to 10% betwween manufacturers (the sizing and other factors affect the testing). So yes, there is a wider variation, perhaps 40%-50% greater variation than glass. Not enough to cause alarm, and certainly not enough to de-rate to E-glass properties.

    Second, basalt is fragile. Bending the weave can leave a lot of broken fibers behind. This happens in glass, but the sizing used in small amounts with glass almost eliminates this beyond the mild nuisance level. Basalt requires more treatment to reduce this, and that impacts adhesion to the resins. It's a balancing act. Basalt used in an un-sized form to maximize mechanical strength can lose mechanical strength if not handled carefully. It is also really, really irritating if you do not protect yourself well.

    Third, basalt has a rather extraordinary low pass feature that is amazing to exploit in certain (i.e. optical stabilization) systems. It is relatively straightforward to reduce Q-factors by more than a factor of two using basalt over carbon fiber. The structure is heavier, but between the cost savings and damping, it means I can use a lot less power for platform stabilization. It can be remarkable. This property is often overlooked because kids these days are CAD/FEA slaves these days and few know how to recognize the impacts of damping in these models, and controls people are usually EE's with little grasp of mechanical details, and common FEA tools themselves are not really very strong in this area for providing more than mere resonances with any reflection in real testing. So basalt ecomes a serious competetive advantage for a range of precision applications where vibration is important.

    Fourth, basalt is better in UV and salt spray environments. This isn't super important since the matrix often is the weak link, but it helps.

    So- it's heaver, reduces vibration a lot, slightly wider in specification tolerances, better at adhering to resin when used unsized, worse when sized to be nice to work with, and it's cheaper than S-glass.
     
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