Beginners mix?

[CPUNeck]

I've perused around a bit looking for a "standard" recipe for a ferro mix without much luck.  I haven't prepared my Bio yet, but hope to during this next week.  I'm interested in designing and building a custom "container" smaller than a standard shipping container.  Then I'll build a custom trailer (like a roll off) that will be used to trailer this container and haul it around.  So even though it's cement, I'm hoping it being subjected to fairly constant cycling, it isn't going to crumble.  This container will be 8' x '8 x 12' with a ramp door at the rear, and a side door.

I'm excited, and need to get crackin on the materials needed along with their concentrations.  Then I could build some test parts to test for strength.  Not sure if this site does well with pics, but I'm pretty good at documenting projects I do.  This would be no exception, and I'd love to share the information.  Unfortunately being in TN makes it hard to attend one of the classes, so hopefully this is a skill I can acquire from the school of "not so HARD" knocks. 

Thanks
-C

[Chris Glasspool]

-C,

Actually the recipe, and technique that has been recommended, has been repeated in different ways over, and over in different topics, threads, but for you, and just in case it isn't easy to find, I will repeat it again.

Mud recipe: 1 part Ordinary Portland Cement / 1 part Masonry Sand #30, 10 percent to the weight of cement to be flyash added. Use a water reducer for best effect, as you want the water content to be as low as possible and still have a workable mix. The water should be no more than 40% of the cement used by weight.

Metal lath, or expanded lath, or plaster's lath, or diamond lath, or blood mesh (you'll find out why this name later) is all the same thing, and comes in three different weights The  heavier the weight the stronger the final product. It is all 27 inches by 96, and is used for stucco work. This is the recommended reinforcement. No rod, not tying, and don't buy self furring, dimpled, or ribbed - just flat.

The process: Lay down a 1/8 inch layer of mortar, and push the mesh into the mortar until it is fully stuck down. Then lay a layer of mortar against the mesh until it about 1/8 inch covering this layer of mesh, then repeat the process until you have at least two or three layers of mesh down. The last layer of mud will just cover the surface of the mesh no more.

You are doing this process against a removable mold. The mold is unique to your project, but you can get some ideas on the subject under the topic of molds. Your mold should be waterproof and not soak water from your mortar.

About laying out mesh: No seam should lay directly on top of the seam below (offset by as much as possible). You can turn mesh over so the the holes (cups) hold the layer above from slipping. You can turn mesh layers so that the directional strength of the mesh is turned to the best advantages for the anticipated stress loads from layer to layer.

Is there another way? Yes, the traditional, or skeletal process of which normally a steel armature is constructed, and then is fleshed out in mesh and mortar. Labor is increased by 80%. Material cost goes up, and problems can occur due to mortar bruising as it is passed through several layers of mesh, or voids left where mortar doesn't reach. I suggest Stanley Abercrobie's book which is in a recent topic, and the book is now being reprinted.

I too want to attend the classes from afar (Chelan, Wash. the Faux Bois Class), and so I agree it is hard financially to attend, but I have attended the Laminated Class previously, and found it well worth it. Only one person out of the group was local. It is a simple craft. but it takes a lot of practise to do it right, and do quality work. I didn't mention edges here, or acrylic skim coats but as you get into your practice pieces we can go into that or you can look through the discussion history.

Good luck - chris

[CPUNeck]

Chris,

thanks for the well thought out response.  I am not familiar with "flyash", something available from local building supplies?  Great info on the receipt, compounded medication for years so count on accurate % to weight ratios.    How about glass fibers into the mix?  Easily upped my slabs from ~3500psi concrete to close to 6k psi. (what my engineer said anyway, never had problems out of those pours though)  Wonder if using the wire mesh with the fibers added to the receipt could yield a stronger finished product.  For vertical and overhead work, how do I keep it wet for ~30 days without having water constantly spraying on it?  TIA

-C

[Chris Glasspool]

-C,

FLYASH: It is common. Byproduct of the burning of coal. Can be found bagged in 25 pound sacks in some areas in building supply places like Home Depot. In other places it can be purchased from specialty stores that provide block or tile. Concrete batching plants usually carry it in a silo, and some will sell it, if you collect it. Nasty dust - 3 microns in size, makes the mix permeability tighter - water resistant. Not necessary for test panels. Also brings the psi up. Read the topic by Enhance (Grant) - possibility exists that this product may be a substitute if needed.

FIBER: Good stuff for concrete, but hangs up on the mesh, and slows you down, as it may stiffen the workability. It also can hang up and cause small voids as it hangs up around steel wires. FC does not need crack control. The amount of tensile strength that you get from steel mesh will make the tensile strength garnered from fibers not worth the trouble, but try it and let us know, what you find.

CURING: I use Jasco's; Cure and Seal (common in big box stores - lumberyards - other brands too). Acrylic that is sprayed on after the initial set. Alternative is to use Acrylic solids to 9% in the surface coats. This may lower your working time though. You could try a bottle of Acryl 60, from a ACE Hardware Supplier. They may have to order it in for you.

WORKING OVERHEAD, AND VERTICAL: Working overhead is not possible laminating, and probably not possible with the armature method either. In either case, you wouldn't want to. Think difficulty, time, and quality of work performed. Your mold would need to be under your ceiling, or if doing traditional work you would get above the work, and use gravity. This mortar is not like a wet grout; it is more like clay, or mastic. You can laminate vertically. but it will take more skill. If you can flare your design sides away form shear veritcal, so that you are working with gravity, you may find that more acceptable.

- chris

[Chris Glasspool]

-C,

You mentioned documenting the project with photos. The topic threads do support photos, as evidenced by some of the threads having photos, though I noticed that some photos mysteriously vanished. I have meant to ask the Web Master about that. Also, if you go to the home page you will see a gallery of projects, and photos. any member can utilize this area too.
Good luck , and let us know how it goes. - chris