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Thread: The OT thread V1

  1. #3561
    Quote Originally Posted by ironyusa View Post
    Actually, I found an article dated back to 2015: https://www.researchgate.net/publica...nt_Replacement

    I also find this stuff pretty cool: http://www.framcos.org/FraMCoS-6/164.pdf
    I like that first article. They put a material in it that will make calcite or something similar which is a pozzolan and it made the concrete stronger when they left the cement and water weight the same which essentially lowers the water to cement ratio which is how you make stronger concrete. Not sure what kind of compression test they are doing with the small rectangle compression samples, not a standard cube like europe or cylinders like us so I am not completely sure how to make out the compression strength data. They dont go into detail on the any of their apparatuses on how they were testing which is a little fishy.

    The second one does a much better job of stating the amount of bacteria that is in the concrete and seems they are going more for the self healing research then adding more initial cementitious material. Again they did a pretty rough job explaining their testing apparatuses, the bending test is usually a 3 or 4 point test with conc, as pure tension samples dont really exist in concrete. The compression test if they used the same beams it would be strange. They did not seem to add strength over the 28 day cure time with the spores vs without, which is more in line with the type of research and results that my old co-worker did.



    The carbon nanotubes is the way of the future that we are still waiting for, hopefully someday the dreams of those self erecting structures formed from them can be realized.

  2. #3562
    Quote Originally Posted by pbjosh View Post
    The bacteria and self healing is separate from the strengthening process. You can actually make concrete objects with just sand, water and the bacteria. It is rather brilliant. There was an artist who was making chairs with that process. Who uses urine. https://www.dezeen.com/2014/02/08/st...peter-trimble/

    Now nano platelets most likely could be harvested from several food wastes, and there has been research into also using nano cellulose also: file:///C:/Users/jcoray/Downloads/A%20REVIEW%20ON%20EFFECT%20OF%20NANO%20CELLULOSE%2 0ON%20CONCRETE-1963.pdf

    We were able to make some very high strength concrete using Grace Admixtures by radically reducing water, and 12,000psi concrete for table tops and counters is fairly easy to make. My father in law does it as a side job. So you could reduce the concrete if you used admixtures properly also, since most just need to nail 3000 psi in 28 days. We were hitting the machine testing limit of 26,000 psi in 28 days.
    That is an interesting use for piss, really anything that forms crystals to encase another particle can be called concrete, it is great when they find uses for it.

    For the 12,000 psi mix you are looking to be in the 20% range for the water cement ratio, which is definitely doable with some superplasticizer. the standard mixes will fall between the 40%-60% range for workability but that will give you your 2500-4000 psi mixes with 3"-7" slumps. You can add some air entrainment to that to get a higher slump but too much will hurt strength. The Super Ps are the real way to go without the addition of other range pozzolans. One of my old graduate students made a flyash mix with plasticizer for eccentrically loaded column research and he made some 4x8 compression cylinders to have that data. He did his 3, 7, 28, and 56 day tests then left the rest for another year. His 56 day numbers were around the 12,000-15,000 psi range. The ones we tested the year later were closer to 30.000 psi, as fly ash continues to cure for a much longer duration than portland. It was funny, everytime one broke it sounded like a shotgun going off, and the machine ended up walking a few inches when the sudden unloading of 400,000 lbs was happening.

  3. #3563
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    I know this is VERY basic, but pozzolans = the binder materials that comprise cement? Cement is used just because it's a material that pours wet and dries hard, right? Pozzolans just are the components that let that take place?

    Or, are pozzolans a specific category of ingredients used in "normal" cement and cement can be made up of any number of ingredients?

    Then you have the aggregate & water which I understand. There's also additional additives for modifying the properties.

  4. #3564
    A pozzolan is a cementitious material. Basically anything that forms a crystalline structure when mixed with water, I think the reactions have to be exothermic as well but dont take that as gospel.

    The most common pozzolan is portland cement, which is a mixture of a few different pozzolans and is refined through time. Even something like grain size is a refinement, for example if you are looking at the basic ACI approved concrete design procedure that is referring to portland cement that was availale during WWII, and that design procedure was made to assist engineers during WWII to help make quicker decisions when trying to mix concrete. The real point I am trying to bring up with this is that Portland Type 1 now is as fine as Portland Type 3 was back then. Type 1 is your standard portland, type 3 is your high early strength portland. The smaller grain sizes allow more water molecules to touch to surface area of cementitious materials leading to more reactions sooner, and also leads to a fuller reaction of available material. Coincidentally concrete also sets hotter now then it used to and that is a common way to check the mixes efficiency in using its available cementitious materials.

    There are 3 other mainstream pozzolans that are used in the USA as substitutes or enhancements to portland. Silica Fume (Part of portland mixtures as well), Fly Ash (There is top ash which is a pozzolan, and bottom ash which is a fill material), and Slag (which in some cases completely replaces portland in certain applications)

    Silica is great at giving you high strengths early but will eat a ton of water so you develop micro-cracking easily if your curing process is not on point, it is also really carcinogenic.
    Fly Ash is great at adding strength after the usual 28 day mark, most fly ash mixes will have a 56 day test as well to get the most out of it.
    Slag is a good substitute for portland especially under salty conditions, a lot of road base and bridges up here will have a slag and sometimes a fly ash mix design.

    There are 6 standard types of portland as well, though you will only really deal with type 1 and 3
    White Portland is considered a type now but it is not much different than Type 1 just easier to dye.
    Type 1 is standard portland
    Type 2 has sulfate resistance so it can be used in things like bridge decks (most type 1 portland is now type 1&2)
    Type 3 is high early strength
    Type 4 is slow reaction portland, if I remember correctly, so it is something that is more available in hotter climates to slow down the reaction process
    Type 5 is really sulfate resistant but a bitch to work with and very hard to source.

    Then their are the experimental pozzolans that we have been discussing the sulfites and calcites and such.

    Then the other area of research is admixtures, we were discussing superplasticizer a bit earlier which disperses water molecules in the mix to get better coverage of the pozzolans and allows you to reduce the water needed to wet the mixture. It can work either to make higher strength concrete by reducing your water to cement ratio, while allowing the mix to still be workable.

    Air Entrainment is a usual admixture, which is basically just dish soap funny enough.

    There are retarders which are basically sugar

    Accelerators which is a chloride like bleach or chlorine tabs dissolved.

    bonding agents, usually epoxies.

    And a whole plethora of others that do random things to the concrete for specific applications. Another example is aerated concrete which is a portland and sometimes sand mix that they mix aluminum powder in it, because portland will oxidize the aluminum quickly and they then autoclave the material to rapid cure it while accelerating the aluminum reaction which traps the gas bubbles in the cement. This leads to a decent strength floating concrete. University of Alabama used to make their concrete canoes that way a long time ago, NASA used to let them use their huge autoclave to cure the canoe. That got ruled out of the competition as an unfair advantage.
    Last edited by Florypb505; 10-24-2018 at 08:25 PM.

  5. #3565
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    Thanks for taking the time to post that! I really appreciate the explanation. I had the terms for pozzolans and cement backwards in my head.

  6. #3566
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    For the 12,000 psi mix you are looking to be in the 20% range for the water cement ratio, which is definitely doable with some superplasticizer. the standard mixes will fall between the 40%-60% range for workability but that will give you your 2500-4000 psi mixes with 3"-7" slumps.
    The Grace plasticizer was amazing. High Slump, and we just needed to tap the outside of the molds. Vibrating just dropped the rocks to the bottom.

    We did do some prototype fly ash and rubber concrete, which was for sound absorbing road wall construction. It was very low slump though - almost unworkable. More like tar than concrete.

    It was fascinating, but I switched careers before we got to do much more or learn more.
    Josh Coray
    J4 Paintball
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    www.j4paintball.com

  7. #3567
    i have recently been introduced by a friend who is constantly trying to get me into motorcycles with the perfect "gordon" motorcyle.

    the Honda CBR250RR. 19,000rpm, 45 hp. max torque: 17ft*lbs. ho boy the want is strong.

    https://www.youtube.com/watch?v=6TzlX-mybgQ

    mother of god i want that in my life.
    Last edited by cockerpunk; 10-31-2018 at 10:53 AM.
    social conservatism: the mortal fear that someone, somewhere, might be having fun.

  8. #3568
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    the 90s 4 cylinder one? That's cheap enough to buy on a whim
    "So you've done this before?"
    "Oh, hell no. But I think it's gonna work."

  9. #3569
    Quote Originally Posted by Lurker27 View Post
    the 90s 4 cylinder one? That's cheap enough to buy on a whim
    yeah, certain death on a whim is about the only thing stopping me for getting into bikes. they are so cheap they make fast cars totally and completely irrelevant. want to run 10s? k, 6,500 dollars please ....


    I'm so spoiled with my fully caged car though now. its real comforting.
    social conservatism: the mortal fear that someone, somewhere, might be having fun.

  10. #3570
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    In a few years electric cars and bikes will make performance metrics even more irrelevant, too. I love that Honda engineers were like, "yea, 4 cylinder 4 stroke 19k rpm that's the call here."
    The 90s are honestly the golden age of automotive culture to me. Crazy how it corresponded with my adolescence! Every engine now is the same boring small turbo'd thing

    I'm completely out on bikes as an ownership proposition because there are too many idiots. Danger = risk * consequences

    Lost a good friend on a bike to a drunk driver from the oncoming lane crossing all the way to the opposite shoulder. My boss has a cool little 90s honda cafe style bike that he does the backroad commute on sometimes, I'm sure it's super fun but I'm definitely too scared (plus #wifebanned).
    "So you've done this before?"
    "Oh, hell no. But I think it's gonna work."

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