Hi Carrie!

Congratulations on tackling a big project and finding a creative way to do-it-yourself!

I must admit I don't do tufa as much as portland/sand/water. I add a bonding agent too but don't know if it has made a lot of difference. I just do it just in case. (I add about 1/3 cup of bonding agent to the first batch of water I add to the portland/sand (1:1-1/2).

As far a color goes, originally I was casting leaves and opted to airbrush the paint on to the cured leaf. I used a bright yellow (since that was the vein color and undertone in the elephant ears I was casting) and then went to HD carrying a fresh leaf and had them scan it and got a qt. of the exact green color of the leaf. I mixed that with a bit of bonding agent and water and top sprayed the leaf. Incredibly realistic!! You may want to prime your piece before applying color but it all depends on the wear it will get. In the future, I plan on using green concrete colorant purchased from HD (added to the dry mix before water) even though it isn't exactly the color of the leaf, in the event any chipping of the leaf edges occurs.

If I were making stones like you are, I would use the powdered colorant. The color exists throughout the piece and no amount of wear or chipping will show. Boxes of these colorants are available at HD and I have found terra cotta (red), Yellow (soft golden color), black (charcoal at best) and green for under $4 a box. I use a scoop when adding portland that is probably 2 cups when full. I use 1 tablespoon of colorant to each 2 scoops of portland, regardless of how much sand is added. Add your colorant to dry ingredients, mix well, then add water.

The colorant is decieving. You won't see the color in the dry ingredients until you start to add the water. You can always sprinkle more colorant over the wet mix and blend well until you get the color you want.

Sorry I have gone on so...

Good luck...and post pictures of your progress!

A

Not all pigments, especially black pigment, is created equal.
I can do coal black concrete with the one I use.
I have another that regardless how much I use it won't give me pitch black.
But I have to replace the sand with copper slag to get pitch black. Not a problem because it doesn't cost much more than sand.

Not all pigments, especially black pigment, is created equal.
I can do coal black concrete with the one I use.
I have another that regardless how much I use it won't give me pitch black.
But I have to replace the sand with copper slag to get pitch black. Not a problem because it doesn't cost much more than sand.

I just want to remark on the 1:1 recipe. If you mix portland cement with water, it will have NO strength. You have to have something to give it strength. Sand does this. In concrete sidewalks, they use sand AND course stones. Too much cement weakens your pavers. Just cement and peat would also be very weak, as the peat will eventually decay away(which is why people use it to create a TUFA look), leaving you with nothing in the 1:1 recipe. They would not work for you. If I were you, and you wanted to create the TUFA look, I would mix 1 cement 1 sand 1 peat. Just don't go to all that work and have it crumble on you because you thought more cement was better. It's not. I wish you luck with this huge project!!

Regarding "strength" of concrete...Depends on what kind of "strong" you are looking for. Today there are liteally thousands & thousands of formulations, each with a specific end result in mind. There are even flexible formulations that exhibit the unheard of concrete property of being able to bend, twist and flex. However, for most applications where compression and resistance to wear are the prime drivers, the old 1-2-3 formula is still one of the best & cheapest... (1 part Portland - 2 parts Sand - 3 parts Gravel or Rock). Adding Fortifier, microaggregates and/or fibers will only strengthen it further.

One important added note...Regardless the formulation of the "dry" ingredients...the strength and durability of any concrete mixture is greatest with the least amount of water. You can get it down to 14-15% by weight with water reducers such as superplasticizers. Difficult to do without a mechanical mixer, but it can be done.

OK,
Thanks for mentioning that sand is what makes it strong.
Where do y'all find cheap sand? It's $4 for a small 50 pound bag.
Nobody has mentioned the cost of hypertufa vs cost of pavers. How many blocks will 1 94 pound bag of portland mixed with 3 bags of sand and some peat moss make? Let's say the blocks are 4" by 4" by 4". Because just the ingredients will cost at least $20. And that $20 doesn't include colorants.
One more question: the fibers and fortifiers that you mention, where do you get those and what exactly are they called?
Thanks

The math is too intimidating for me but consider this...it'll cost you only what a manufacturer's material costs would be. Home Depot and/or Lowe's usually has a couple of different brands of fortifiers but you will probably have to track down a concrete specialty supplier to find fibers. Check the phonebook or call a ready-mix company and ask where they get theirs. See the link for a wealth of good info. Best of luck.

Here is a link that might be useful: The Concrete Network

Around 65 blocks without the peat.

cweathersby-
Regarding cheap sand: I get my sand at a local yard materials place that carries sand, gravel, bark, topsoil, etc. They let me come in and shovel it into my pickup. For $10 I can shovel in a half ton.

Not all sand is created equal.
Is it meant for concrete use? If not be careful.
We have sand in my area that even when washed and screened is useless for concrete because of mineral and salt content.
years ago, an entire small town was build with the stuff before they realised the sand and gravel was bad.
you never saw so much crumbling concrete in your life.