Timeline for How to design a reinforced concrete ship keel?
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Apr 25, 2016 at 16:51 | comment | added | Escoce | @NamSandStorm what if I used railroad track instead of rebar? It would both add to the weight of the ballast by displacing more concrete, and it's loads stronger than rebar. Do you think this might mitigate some of the weakness? | |
| Apr 14, 2016 at 7:27 | comment | added | SlydeRule | The proper term for "concrete recipe" is concrete mix design. It is an aspect of structural engineering. Concrete is strong in compression but weak in tension and bending, no matter what the mix design is. So whatever happens to a concrete member, it will be subjected to a combination of tension, compression, bending and shear. The reason we provide steel is to mitigate the weaknesses of the concrete. So your approach to just attach mass concrete with some steel will not work, sin you are not addressing the weaknesses of the concrete. A fibre reinforced concrete may work however. | |
| Apr 12, 2016 at 15:49 | comment | added | Escoce | I have been reading up on it, and I do think I am getting the gist of designing a good concrete recipe. The rules of thumb I've heard in the past might be "good enough" for just a regular old slab of concrete, but I was looking for what's optimal. So it appears that graduating the aggregates from as large as practical to smaller is the best thing to do, but I don't know what the proportions are nor how to figure out how to get that tightest knit of graduated aggregate to sand and cement to cover it all, and I know I want to minimize water while still allowing the concrete to remain workable. | |
| Apr 12, 2016 at 15:47 | comment | added | Escoce | Don't worry about the effects of ocean water. I know very well what it is, what it does and how to minimize the effects of galvanic corrosion and oxidation. That's not the issue, the issue is the best more durable and impact resistant recipe there is for concrete. | |
| Apr 12, 2016 at 13:41 | comment | added | Escoce | @NamSandStorm you aren't quite getting the gist of the question. The concrete is not meant to serve to protect the wooden keel. Although it does have that happy consequence, it is secondary. It is simply meant to provide ballast, that is in nautical terms means dead weight at the bottom of the keel to produce a few effects by lowering the center of gravity helping keep the boat upright and therefore afloat and moving faster through the water. I simply want a concrete recipe that will provide the most durable concrete keel ballast. Weight is not an issue, in fact heavier is better in this case. | |
| Apr 12, 2016 at 12:19 | comment | added | SlydeRule | @Wasabi, the chemistry in ocean water is a corrosive to most ordinary cement types. This means the cement paste chemically corrodes over a period of time. As long as the environment around the reinforcement remains alkaline, things should be fine. As soon as the concrete is compromised, you have a scenario where the steel is exposed and you are left with unprotected, bare steel. This would be in a submerged state most of the time, so less exposed to oxygen than in the atmosphere, thus the corrosion process is delayed. | |
| Apr 12, 2016 at 11:34 | comment | added | Wasabi | I don't think there's really much risk of corrosion, actually. In the comments below the OP, they state that the concrete will always be submerged (except under stormy weather, where it might be momentarily exposed for a few seconds at a time). And without exposure to air, oxidation won't occur. | |
| Apr 12, 2016 at 10:44 | history | edited | SlydeRule | CC BY-SA 3.0 |
corrected grammar and spelling
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| Apr 12, 2016 at 8:51 | history | answered | SlydeRule | CC BY-SA 3.0 |