Backyard Aquaponics
A place to discuss aquaponics

Ok Well I have started this thread to share some of my experience and what I have researched about Ferrocement construction.

The Basic concept of Ferrocement is to be able to build an inexpensive structure that will last a long time. Most of theses structures are built in very hard to reach places and so require the minimum amount of supplies possible. Most items constructed from Ferrocement are water tanks in the 1000L-10000L range. People have also used Ferrocement to construct complete homes.

Most rurally constructed Ferrocement will use only chicken wire as it is easier to carry into the site and it is very cheap (also easy to obtain). But if you were to be constructing fish tanks or even growbeds, rebar would be a good idea for the added strength.

Here we usually have two methods. Above ground and under ground tanks.

These are very basic methods I have obtained through watching two tanks been built and helping with another. Also a lot of research from the net.

First above ground:

First step is to pour your pad. It is usually about 15-20cm (6-8”) thick. With a web of rebar (3/8”). L shaped rebar pieces are added to the base so that they will be solid in the concrete and reach to the height of the top of your tank. Then a mix of cement, sand and aggregate is pour into the base. Note: We usually used a dirt/sand form as it saves us hauling in extra form work.

Next the tank. You will need a form for this we usually make them out of scrap sheet metal (I have seen on even made out of bamboo before). Wrap a layer of chicken wire around the circumference of the tank both inside and out side of the rebar. Then set up the oiled form work inside the tank (it can be external but internal is easier no climbing).

Next mix up the cement and sand. 2.7 parts sand to 1 part cement (play with the mix a bit to get the strength you feel you need we use anywhere from 2 -3:1). Enough water should be added so that when you draw your finger through the concrete it will slowly settle (i.e. low slump). Then just plaster on your mix (mud in the states). Make sure to fill in all the space and to keep it damp as you go (we use a spray bottle).

Under Ground

Step one dig your Hole. We did one of these tanks for a friend of ours out in the village he is a 60 yr old man. We told him we were coming to put a tank in the ground. He asked where and how big. We show up the next day shovels in hand and find this 60 yr old man and his wife at the bottom of a ~2m deep hole. Needless to say he really wanted a water tank. One point on hole digging the bottom need to be 90deg to the wall, so that your base will not end up to thin.

After the hole is dug we make up clay slurry and spread it on the walls to seal the tank (the clay stops the surrounding earth from absorbing water out of the concrete). Then we pour the base. Again you will want to use rebar and the design would be similar to the above ground. Usually for under grounds we don’t bother with it as the walls a well supported by the soil structure around them. Note: If you wanted to make a cone shaped base you could make the base out of normal Ferrocement and mold the rebar (and hole) into the cone shape.

After the clay is on and the base has been poured we start with a layer of Ferrocement (you might need to dampen the clay a bit so the moisture is not removed from the cement). Next a layer of chicken wire or two and then more Ferrocement. If you are building a cone you could do the first layer of Ferrocement and then put down the chicken wire covering your hole tank (including cone base) then you could add pre bent rebar between the layers of chicken wire and then go at it with the Ferrocement.

SO yeah that’s some basics.

A little side note. Some people will use rebar then 4” mesh or driveway mesh and then hardware cloth or chicken wire.

Best rule to go buy is to make sure your 2 or more layers chicken wire are not laying flat against themselves. And the holes are offset so you get ½” gaps.

This is probably a bit confusing as I have been interrupted a few times writing it but feel free to ask me any questions. And have a search of the net to see what people have done with it.

JT

JT, what is please?

Thats chicken Wire J sorry working to late at night

thanks JT, sleep deprivation is a reasonable excuse thanks for the info

Hey JT...what are the links again, I'm sorry I lost them. Are there and pictures of ferrocement tanks?

These are the two best links i have right now. I will shoot some photos tomorrow.

Link 1

Link 2

Thanks for that JT - before discovering IBC's, I was looking at this kind of thing for my tanks - had compleately forgotten about it

When I've done concreting before (real basic stuff like shed footings) I've read on the packet that at certain mixes of sand to cement it is meant to be water proof. I think I've also heard about an additive that is added to concrete when you order it in a truck.

The links that JT posted talk about painting the inside with a waterproof sealing paint. Is it necessary? The concrete troughs that we have on the farm and the concrete tanks that I am familar with havn't been painted. Does anyone know why?

Stuart

The main reason for the painting is that they want to add colour to their walls because they are building a house. If you want to paint concrete waterproof paint is a must if it will get wet.

Some people do seal the tanks with pool type paint but we feel the 2.8:1 sand cement ratio is good enough. We also sometimes add a additive to the concrete but i could not tell you what it is right now as i don;t know what it is called in english. I will find thta out.

you can also add oxide powers to cement to give it colour, instead of painting it

Geez I will have to do some slapping if you keep that up!
we will have no more about oxides thank you.
If you want to colour concrete then PM me.
Even if you are in the US.
there are some really good plant based stains if you want to know...
C1

LOL

am - I had my first meeting in perth today at 930am( 4hrs HSM ) and 2nd at 2pm 600k round trip just as well I can say I had a productive day.

C1, I was for many years an avid yatchsman and remember the 70's rage for home built ferrocement yatchs...

If my memory serves me well, I recall that almost universally those involved had problems with waterlogging/reverse osmosis while building or sometime after launching... to the point where nobody really uses ferrocement any more for boat building....

Is my memory playing tricks on me or are there problems with maintaining waterproofing of ferrocement units, be they boats or tanks....

Or was it just lack of knowledge of those involved and/or obselete techniques.

Underlying question.... how good and durable is ferrocement for the purpose of tanks??

memory better than mine...
how this
my uncle steve (true name) built a 54 ' ferro walnut and teak fitout my dad spent years there at freo with his bro, must have been talking of the war. silly old buggers... where U steve used to live in Mos pk there is a 4 level 10000sq mtr compound, cost $25m Au to build the house and 7 years.

would I build one? No.. in a word.
Even fibreglass can suffer osmosis