The Plaster Mix for Parabolic Stress Skin System

High performance mortar mixes usually can't make a good plaster but replacing high volume flyash with smaller amounts of ultra refined pozzolan, Boral Micron 3, and adding spherical closed-cell aeration does the trick.

Category:

Science & Technology

Tags:

• cement
• micron 3
• parabolic
• stress
• skin
• ferrocement
• eucon
• SPJ
• sculpture
• PVA
• Mearlcell
• sustainable
• construction

[labotamizer]

Hello. I want to thank you for a very informative video. My problem is I am in England and I can't get all your ingredients. I own a barge which is corroded inside and out. I can't afford to take her out of the water , so my only option is to ferro her from the inside. I intend to weld rebar between the ribs and mesh or chicken wire or whatever you might suggest. I can vibrate the plaster to exclude air and voids. But , if you had time to give it some thought, I would value your advice.

[ShambhalaVillage]

Try & test your own variation. Use 30 fluid ounces of Silica Fume. Replace 25% of ASTM 200 mortar sand with a much finer, even gradient quartzite sand, such as medium grit sandblasting sand. Use compound from LiteBuilt LLC, UK Available, for aeration. Many options for super P. Use one designed to prevent segregation + provide long workability. Doesn't have to be a polycarboxylate. Skip rebar and chicken wire. Too old school RC, not modern thinshell. Do lath LFC skin only. Study procedure.

[elvieken]

have you tried or given thought to using fly ash? How long does this take to fully cure for that psi? Could it be pumped like shotcrete? How many psi could the roof hold on this?

[ShambhalaVillage]

@elvieken The Micron 3 is Flyash refined. 0 - 10 microns with 80% being 3 microns. Regular flyash is 0 - 30. This is why you can reduce the amount of flyash by 4 fold with the same effect but less water demand. A lot of air on the nozzle dries it out. Still, you shouldn't do more than what you can take care of with tarps and water spray for good curing maybe 10 or 12 mixes a day. Roofs are sturdy because of the stress-skin effect, not the membrane strength so much. < 16 ft spans best.

[bedonner]

Hi Doug, great video- very interesting and informative. I was wondering, what's the benefit of the foaming Mearlcell component?

[ShambhalaVillage]

The Mearlcell 3532 microsphere closed-cell air bubbles is not air entrainment but is what makes the shell permanent. The aeration here makes this high-strength mortar, but more importantly low-shrink mortar which grips the reinforcing better, into a workable plaster - great for overhead, compatible with acrylic + water reducer. Closed cells hinder moisture intrusion, cushions impact and arrest progressive rust and removes other internal strains, such as ice, that are caused by expansion.

[porpoisefathom]

Doug- whats a cubic yard of this cost to produce? i need to make about 5.5 cubic yards...thx!

[yeo2k985]

Hi. Is an interesting video! I learn much from you. I wonder how is the strength of this mortar. Is it very high strength?

[ShambhalaVillage]

Why not use a stay-in-place form like the system presented here. That way both surface shells would provide a provide a water proof membrane and the cellular concrete fill could be potent moisture barrier as well. Also, the overall density of your 15 inch shell with a 28 pcf cellular concrete fill would be around 50 pcf with the steel and everything so if if the hull was breeched, and your sub filled with water, it would float. Wood forms can create a serious cost hurdle for a project.

[porpoisefathom]

hi there--i want to build a horizontal form that is blimp shaped for a submarien hull...other than ferroe cement for this.how would i builda wooden form?..and would i need a mold where the cement would be enclosed?..or can i trowel on the cement all around the hull? i am worried the gravity would pull out the cement at the keel area...any ideas..i know your not a boat builder but maybe you know somehting about molding strutcures like cement culverts etc?