Posted by Angel on March 29, 2002 at 10:25:12:
In Reply to: Re: stained glass stepping stones posted by Gary Dodge on March 29, 2002 at 00:40:45:
Carol, Gary wrote and asked me to come here and see if I could add to his replies on your stone problem. I know that you're just gathering consensus opinions on all the forums and that's OK. You're a member of the Silicon Folly forum where you had your very own thread with approximately 14 replies. In following your posts other places I see that you get just about the same answers everywhere. That's about all the knowledge on this problem that experienced people can give.
The Stepping Stone Manuals on Silicon Folly will give you THE strongest formula you can find anywhere. I know you don't want to change horses in mid-stone and want to keep using the same mix that the original projects used...so I can't help you with a good formula. With apologies to Gary who is a distributor for Diamondcrete, I am going to tell you that it's the LAST product to use if you want weather resistant stones with lasting strength. DC is 30% gypsum. In any case, Gary and I have already had this discusion here...hahaha. It's very much to his credit and open-mindedness that he asked me to come and discuss your problem, knowing that I am totally anti-Diamondcrete
I WILL tell you that if you're pouring a thin Mortar "topping" layer, that it's the weakest part of the stone and will be the first thing to crack if anything does. I would advise you to put 1/2" NYLON FIBERS in your stone mixes and to use liquid ACRYLIC in place of (or 1/2 and 1/2) water.
The concrete mixes you see in pre-bagged form that state reinforced or fiber-reinforced have fiberglass fibers. That helps, but like everything else in pre-bagged form it's not the best kind of fibers or in the right proportions to do much good. They also have too much sand.
FUMED SILICA (not the same as silica fume or fly ash) added to the mix, fills the tiny spaces around the sand. It replaces the air and water that's usually held there and makes an unusually dense and MUCH stronger stone.
Small structures like stones DO NOT need WIRE reinforcement. It doesn't really strengthen them. I get mail from people crying about how their conventional concrete stones cracked and crumled leaving them with a piece of rusted wire that had some chunks of broken concrete hanging on. Hahaha. That, and the fact that it rusts and often sticks out of the sides when not perfectly used are some of the prime reasons people go looking for a good art-quality concrete formula that will hold up to any kind of climate and stress. We spend too much time making stones to have them deteriorate.
The MODERN method of making stones uses FIBERS...not WIRE. You can look at some of the professinal stepping stone sites on the web like "The Next Step" and find their improved method of using fibers. You can add these to the mix you're using now with no change in appearance.
To be honest, Carol, I don't think there'a anybody who can tell you if your stones will hold up with a tractor mower running over them. I worry about my gardener running a conventional hand mower over mine and try to put them where they will be protected from anything except a weed-eater. You could try making a "test" stone and installing it on a bed of sand in the ground in the path of the mower. I sure as heck wouldn't risk the whole batch of stones until I knew if their placement was judicious.
You've had good advice in all the places where you actually received a response. Now it's up to you to put it to the test.
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: I am far from an expert in concrete and generally just use diamondcrete myself, but here is some of what it is about.
: Many of the reinforcing additives add fibers to the mix that tie the concrete together much like the way the paper in paper mache gives strength to the flour that is used as the binder.
: The acrylic additives add some elasticity that helps to resist cracking.
: A great deal of resistance to cracking can also be achieved by adding a wire lattice of sorts, like mesh in the middle of the stone. This will do a lot to insure survival of your work and will not be visible or change the appearance of the stones.