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Waterproofing Concrete

Home Forums Archive Structure Designs Waterproofing Concrete

This topic contains 42 replies, has 14 voices, and was last updated by Avatar of R-B-Wood R-B-Wood 3 years, 4 months ago.

Viewing 13 posts - 31 through 43 (of 43 total)
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  • #12750
    Avatar of Alan
    Alan
    Participant

    I don’t know all the specifics, but the purpose of the basalt is to add strength to the concrete. I imagine that it may not be as strong (for weight) as steel, but it is still strong enough for many purposes.

    I myself have a similar question: although the basalt roving appears to have very good tensile strength, I don’t know what sort of compressive strength it has. On the other hand, this may not be important, as concrete itself has very good compressive strength – so perhaps the concrete and basalt combination has both compressive and tensile strength – and, in this video, I suppose the concrete had the strength to hold up the weight and the basalt wrapped around the structure prevented the concrete from warping or deforming in any one area, which might have led to a collapse.

    I would like to hear from someone with a better knowledge of concrete, however.

    #12752
    Avatar of shredder7753
    shredder7753
    Participant

    that was a hint for elmer to chime in, i bet. lol

    so, a couple years go by and the stead is all cured and operating so nice, when all the sudden theres a collision… ??? seems to me we might want rebar in that situation, right? like how would the “roving”/concrete hold up to that? of course we would make it more than 2″ thick, which is what they used for the dome, but still.

    #12751

    Alan, yep concrete is a composite material. Rebar holds tension forces the concrete matrix the compression forces only a piece made of a combination of those materials holds ANY type of force. It does not really matter a lot how strong (in tension) the fibers are compared to steel – if they are weaker you just use a bigger amount of the fibers and get (for all practical purpose) the same result in tension resistance. So the material has its merit, no doubth about it. The waterproofing discussion on the other hand is very much finding a “imaginary solution to a imaginary problem” well executed concrete structures are waterproof. Repairs on “non well executed structures” have been executed sucessfully in practice at 90m waterdepth without access to a drydock.

    So all seasteading relevant engineering questions about floating concrete structures are solved. Key is adapt traditional concrete craftsmanship to the special conditions of a floating structure, what burns down to a practical handling and logistics problem most of all – (you can not call mix trucks as usual in land based construction).

    So the discussion “how to alterate traditional materials to adapt for seasteading” is not really necessary. A seastead can be perfectly built with “traditional materials” – who thinks that this is not the case just has a need to read the right studies to update his knowledge.

    On the other hand fiber concrete (glass steel, basalt, plastics, carbon, veggie fibers) replacing steel rebar with other materials is increasingly used in both land and sea based construction so the new material is really nice and could have a place in the seasteading universe.

    Picture of a test of a basalt fiber rebar reinforced beam

    Wil

    concretesubmarine.com

    #12753
    Avatar of Alan
    Alan
    Participant

    ellmer - http://yook3.com wrote:
    well executed concrete structures are waterproof.

    There, of course, is the issue. Anyone who has ever been on a construction site knows that there is great variation in how well executed a project will be. There are all sorts of room for failure: the engineer who doesn’t quite understand one aspect of the construction, the worker who’s more interested in getting his next hit of cocaine than in doing his job, or the worker who purposely introduces a few flaws as a type of job protection – hoping to get paid to fix it later.

    The case of the accident in Boston’s Big Dig illustrates several of these points – one type of epoxy that might not have been sufficient anyway was intended to be used, somewhere along the line a different type of epoxy was actually used, and most likely the workers did not apply the epoxy correctly in any case. Furthermore, the concrete panels were not even necessary, and could have been replaced with much lighter panels. This was a case of failures by engineers, workers, and manufacturers.

    http://enr.construction.com/news/transportation/archives/070711.asp

    ellmer - http://yook3.com wrote:
    Repairs on “non well executed structures” have been executed sucessfully in practice at 90m waterdepth without access to a drydock.

    This is encouraging and good to know. Even so, I would prefer to have several levels of defence, especially if the cost is not significantly higher – and as I imagine such repairs are not cheap.

    We do at least agree that this is a potentially useful development. It also appears to me that it might reduce labor costs, as the roving appears much easier to bend than rebar.

    #12754
    Avatar of Alan
    Alan
    Participant

    shredder7753 wrote:
    that was a hint for elmer to chime in, i bet. lol

    Well, I was kind of hoping ellmer might give his opinion. He is one of the better informed posters here – especially on this subject.

    so, a couple years go by and the stead is all cured and operating so nice, when all the sudden theres a collision… ??? seems to me we might want rebar in that situation, right? like how would the “roving”/concrete hold up to that? of course we would make it more than 2″ thick, which is what they used for the dome, but still.

    Maybe, maybe not. Depending on the size and configuration of the seastead, there may be no need for more than 2 inches of concrete. A very large seastead might want thicker concrete, or not. It would probably be advisable to have a greater number of sealed compartments with thin walls than one big compartment with very thick walls. If a collision breaches a few of those compartments, the seastead would still float – if a collision or other threat breached the thick walls of one big compartment, the seastead would sink.

    So the question is, do you follow the advice not to put all your eggs in one basket, or concentrate on building one extremely good basket?

    #12756
    Avatar of shredder7753
    shredder7753
    Participant

    o ur talkin bout some crumple zones. might not be a bad idea. i understand the basic concept but it would be out of my reach to know the exact mechanics of how best to make those work on a seastead. our concrete evangelist would have some concrete answers for that. i think u do have a good point.

    #12758
    Avatar of R-B-Wood
    R-B-Wood
    Participant

    I’m with Alan on this one. I’ve lived all my life on land, but I like the idea of living at sea, it would be nice to get away from the rediculous costs and some of the rediculous laws. But I have seen enough incidents to know that it’s dangerous and I want to take as many precautions as I can. So all of my designs so far are Semi-Submersible (for protection from storms) and have many chambers, sensors, and pumps (should a leak occur).

    My latest design has a thicker outer hull and a thinner inner hull .5m smaller on all sides and bottom. I then have the space between them broken up into a couple dozen small, perminantly sealed, compartments; so even if an impact were to occur and several compartments become flooded, the vessel would still float. I’d like to go even further in breaking up the inner hull into 8-10 compartments as well, should the inner hull get breached (this design is 7x12m, I should think you would want more compartments the larger you go). This design has 4 large rooms, a passageway, 2 mechanical rooms, and a couple smaller rooms, which with some form of watertight door could be their own compartments if need be.

    So if I were to run into one of Elmer’s subs and put a 6′ hole in my bow I could simply seal a room or two where the damage is and I would have one or two large compartments flooded, and maybe half a dozen smaller compartments, but would still have 8 or so large compartments and a couple dozen small compartments left keeping me afloat until the damage can be repaired and the water pumped out.

    I’m working on getting this design in Sketchup to post on one of these threads before too long, get some input on it.

    shredder7753 wrote:

    o ur talkin bout some crumple zones. might not be a bad idea. i understand the basic concept but it would be out of my reach to know the exact mechanics of how best to make those work on a seastead. our concrete evangelist would have some concrete answers for that. i think u do have a good point.

    #12760
    Avatar of shredder7753
    shredder7753
    Participant

    R wrote:

    I’m with Alan on this one. I’ve lived all my life on land, but I like the idea of living at sea, it would be nice to get away from the rediculous costs and some of the rediculous laws. But I have seen enough incidents to know that it’s dangerous and I want to take as many precautions as I can. So all of my designs so far are Semi-Submersible (for protection from storms) and have many chambers, sensors, and pumps (should a leak occur).

    My latest design has a thicker outer hull and a thinner inner hull .5m smaller on all sides and bottom. I then have the space between them broken up into a couple dozen small, perminantly sealed, compartments; so even if an impact were to occur and several compartments become flooded, the vessel would still float. I’d like to go even further in breaking up the inner hull into 8-10 compartments as well, should the inner hull get breached (this design is 7x12m, I should think you would want more compartments the larger you go). This design has 4 large rooms, a passageway, 2 mechanical rooms, and a couple smaller rooms, which with some form of watertight door could be their own compartments if need be.

    So if I were to run into one of Elmer’s subs and put a 6′ hole in my bow I could simply seal a room or two where the damage is and I would have one or two large compartments flooded, and maybe half a dozen smaller compartments, but would still have 8 or so large compartments and a couple dozen small compartments left keeping me afloat until the damage can be repaired and the water pumped out.

    I’m working on getting this design in Sketchup to post on one of these threads before too long, get some input on it.

    shredder7753 wrote:

    o ur talkin bout some crumple zones. might not be a bad idea. i understand the basic concept but it would be out of my reach to know the exact mechanics of how best to make those work on a seastead. our concrete evangelist would have some concrete answers for that. i think u do have a good point.

    [/quote]

    Woody – a good place to post your sketchups (renders or plain screenshots) might be here:

    http://seasteading.org/interact/forums/community/dreaming-/-crazy-ideas-/-speculation/artwork-share-your-stuff-if-you-dont-

    i think its safe to call all of our work artwork until they’re validated by PE’s.

    #12885
    Avatar of admiral-doty
    admiral-doty
    Participant

    Great find on the basalt fiber. It is available chopped and as cloth, in addition to rebar, http://www.basaltex.com/en/products.aspx and http://www.basaltfm.com/eng/materials_production.html . A chopped fiber foam concrete would float or be neutrally buoyant depending on density with a high strength and castable in molds or sprayable on an air form like the Monolithic Domes. laminated basalt cloth and cement sheets would be very strong. Curved hulls could also be made from the cloth and cement, but is a lot more labor intensive than casting or spraying on an inflatable or collapsible form. The cloth is stronger, as an example, chopped graphite fiber cast epoxy has a tensile and bending yield strength similar to aluminum, tensile 35,000 PSI, while graphite epoxy composites laid up from cloth are as strong as steel, tensile upwards of 100,000 PSI parallel to directions of fibers of cloth plies.

    #12892
    Avatar of R-B-Wood
    R-B-Wood
    Participant

    admiral wrote:

    Great find on the basalt fiber. It is available chopped and as cloth, in addition to rebar, http://www.basaltex.com/en/products.aspx and http://www.basaltfm.com/eng/materials_production.html . A chopped fiber foam concrete would float or be neutrally buoyant depending on density with a high strength and castable in molds or sprayable on an air form like the Monolithic Domes. laminated basalt cloth and cement sheets would be very strong. Curved hulls could also be made from the cloth and cement, but is a lot more labor intensive than casting or spraying on an inflatable or collapsible form. The cloth is stronger, as an example, chopped graphite fiber cast epoxy has a tensile and bending yield strength similar to aluminum, tensile 35,000 PSI, while graphite epoxy composites laid up from cloth are as strong as steel, tensile upwards of 100,000 PSI parallel to directions of fibers of cloth plies.

    Niether of those sites appear to be functioning at the moment. One’s lasted posting was a projection of upcoming sales in 2008, the other the latest date I could find was 2005. For such a strong, flexible, and cheap product you’d think these companies would be booming. I’m wondering what’s not adding up.

    #12899
    Avatar of admiral-doty
    admiral-doty
    Participant

    they both come up ok for me. haven’t looked at how recent the pages are. there’s a lot more under google for basalt fiber. there has been a slump in new construction since 2008. maybe this has affected the basalt fiber market.

    #12901

    admiral wrote:

    ….. For such a strong, flexible, and cheap product you’d think these companies would be booming. I’m wondering what’s not adding up.

    good point. The base problem is – if you do it in standard concrete you KNOW that your structure will last (at least) 200 years – if you do it in basalt fiber concrete you ASSUME that it can last as long or even longer (but you have no experimental data on it).

    Concrete structures are items planned and financed on a long term base – so nobody is willing to take a “uncertainty factor” of any kind.

    Basalt fibers are on the market for a couple of years – when the first built structures reach their birthday 200 and there has still no “hidden problem” arised – people will start to be inclined to use the material “MAINSTREAM”.

    The example shows why seasteads if built in the next 200 years will definitly be built in a material that has successfully been on the market during at least 200 years in some form.

    So bad news for any novel experimental material – it might come – some day but 2-3 generations from now…the first seasteads will be a “new appliance of proven engineering techniques” adapted to seasteading.

    My favorite is something as shown in this video – at the beginning you don’t even be aware that you are on a “unusual building site” you get the picture only at the end when the thing floats out – http://www.youtube.com/watch

    This makes it very easy to estimate general cost per cubic meter built – as the building site and technique is widley the same as land based construction – the structure cost should be “widley the same” also.

    Putting “never seen rebar” on the set means to send all workers and engineers back to school in first place – to finance this over the rebar price will not really work easy.

    Wil

    concretesubmarine.com

    #12942
    Avatar of R-B-Wood
    R-B-Wood
    Participant
Viewing 13 posts - 31 through 43 (of 43 total)

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