As a retired Ferrocement man, the boats were 8 layers of 1/2" chicken mesh, 4 either side of the armature frame . I added trioxide ( stops galvanic reaction bubbles of wet plaster and mesh ) to my mix of 2 - 1 after replacing 15% of the fine sane with a pozzolan like DE or Fly ash, this is why Ferrocement is water tight and NOT concrete..

@paulbriggs3072

2 жыл бұрын

I wonder if vinyl additive sold for concrete would improve toughness and water resistance. Thus corrosion resistance.

@perkar49

2 жыл бұрын

@@paulbriggs3072 No need, ferrocement is very strong and watertight .

My favorite book in the whole of the world is Blue Water by Bob Griffith. He's a true blue water sailor in you guessed it a ferro cement sailboat. So many neglected sailboats out there with fine lines, but too many people are scared to death of cement. Great video, glad I stumbled across it.

my dad built a ferrocement boat in the early 1970's in San Francisco bay.

Hi Matt, Thank you for the great Video. The idea of expanded metal looks great at first but it lacks strength in shear, impact and flexability. I helped build boats from ferro cement back in the early 70s. We did a lot of material test pieces with the department head of the structural engineering at the University of Miami. The four layers of hardware cloth either side of 1/4 inch rebar on 4 inch centers, lateral and perpendicular was the strongest in all directions with an average thickness of 1.12 inch. Second in strength by a slight margin with the same structure, but using chicken wire, had slightly more flex but almost the same axis strength. However each material did not show signs of surface or sub surface fracture. The test panels were 4 inches wide x 12 inches wide. I did a full mockup of a 4 ft x 4 ft section using the chicken wire and 1/4 rebar. A 10 pound hammer was used on the wet cured panel in a 20 ft drop. No damage occoured to the panel, which was supported to either end. The test panels we made with expanded metal could be broken easily by pushing down by hand with the ends supported. The hardware cloth and chicken wire could not be broken in a like way. Try a few tests. The new basalt rebar and lose basalt fibers, shows some very impressive properties for thinwall ferro cement. I made some .25 inch test panels that were extremely strong for their weight. Good luck and best wishes.

@ThePermacultureStudent

4 жыл бұрын

Wonderful additional information!! THANK YOU!!

@DC-uo5hy

4 жыл бұрын

@@ThePermacultureStudent you are very welcome. Give the basalt a try. It does not rust... ever. Several videos on KZread. Basalt rebar and products. Let me know what you think.

@vasillepesh

Жыл бұрын

@@DC-uo5hy do you recomend to use basalt mesh as the only reinforcment either mix it with layers with metal mesh. Another question is pozzolan or pozzolan with liquid glass? Than you for your advices!

I’m glad I came across your presentation. Great information about ferro-cement.

Thank you! That is informative!

Great presentation! FYI, Martin F. Iorns is one person. Here's a bibliography of his work: crasch.livejournal.com/230952.html You might want to look into basalt fiber mesh for re-inforcement. It's made by extruding basalt rock into very thin fibers, then binding it together into various products (mesh, rebar, fibers, etc) with fiberglass resin. It has a comparable strength to steel mesh, but a) it doesn't rust, so your structure should last for centuries without maintenance, even if the cement cracks, and water reaches the mesh b) is much more pleasant to work with (lighter weight, not so sharp) c) you can use thinner layers, since you don't have coat the reinforcement with so much cement to prevent water ingress.

Some Boat builders would say to stay way from the mesh you are using, they claim that expanded mesh is structurally not as sound as others, however in your case, I don't think it matters. Now I don't know, I'm here finding kinds of COOL tech, that we have forgotten.

I live aboard a Hartley 34 ferrocement yacht.

@nigelbenson5287

11 ай бұрын

I live aboard a ferrocement Hartley 39 RORC.

Do you now "cascaje"? IS Very interesting técnica Brazilian for roofs.

how many layers would a roof need?

@ThePermacultureStudent

4 жыл бұрын

Chris is a teacher in our course and answers questions inside the course - I may share more videos of him installing his roof but I don't have any footage of that yet.

What is the formula of the mix to be waterproof?

@perkar49

2 жыл бұрын

The finest sharp sand and best Portland ( 5 ) cement mixed at 2 - 1 ratio after 15% of sand replaced with a pozzlan like DE or Fly ash. and just enough water to pass a slump test, each mix must be exactly the same. I add a few grms of trioxide to stop the galvanic reaction gas bubbles causing a honeycomb effect, not wanted in a boat hull . Last coat of plaster should be 2 mm thick above the mesh , any thicker = hair cracks and to thin = wire bleeds. A good plasterer will give you exactly 2 mm..

Why did ferro-cement boats decline so much? Nowadays they are incredibly cheap second -hand compared to steel or glass boats. And if you compare materials to build a boat it is usually a steel vs fibreglass or sometimes wood also, kind of discussion. Ferro-cement doesn't even rate a mention? What happened?

@perkar49

3 жыл бұрын

Insurance almost impossible to get...very strong boats, if well maintained, and very easy to repair, I have done a few, like a 20 foot hole in a 40 foot hull, piece of cake, low cost materials..good as new..problem is many were badly made, and a nightmare to own one of these..a well made Ferro is a great boat..

The Romans added bone ash to their cement so it could be poured directly into sea water where it cured, plus they used hempcrete, I wonder if hempcrete would be the better material?