How do you make a mold for standard 40 x 40 cement tiles? Can you cast these yourself and make them all look the same? I need some odd sizes and shapes around a pool, and the idea occurred to me to cast these myself. How do I proceed?
Member
· Västerbottens län
· 18 051 posts
Preferably a form plywood, then 2 fixed and 2 loose (screwed) braces so it becomes a 40x40 space that you fill with concrete and tamp and shake it together; rebar is not present in purchased slabs, so with the right concrete, you won't need it either.
Protte
Protte
Tiles that you buy are normally cast with high pressure. I don't know exactly how it works but I have read that they press the mold with about 100 tons. I assume it's just temporary pressure, hardly something during the entire curing time.
It is supposed to make them more durable.
It is supposed to make them more durable.
Member
· Västerbottens län
· 18 051 posts
Factory-cast are made of such dry concrete that they can be immediately removed from the mold, so it's probably necessary to press them to remove all air bubbles.
Concrete should never dry quickly, so stacking them up high the next day is probably not wrong, and watering them daily.
Protte
Concrete should never dry quickly, so stacking them up high the next day is probably not wrong, and watering them daily.
Protte
Is it possible to cast larger on-site, like 1 x 1 meter? You can cast one every evening, probably better than laying tiles. You can compact the entire gravel area at once, shape a square, and build with 3 sides the next day. That way you can reinforce each "slab" individually. The ones I'm considering casting myself are those I want around the pool, 20,000 SEK for a little stone is not OK for my budget!
I have poured many slabs myself in various dimensions. I cast them myself because I think it holds better (always reinforce), you can get any dimensions you want, it generally looks nicer, and I usually polish them with a diamond grinder which is not possible with store-bought ones that are too porous.
My standard slab is usually 40x40 cm, just as you thought, I build a frame of 45x45mm battens which I then screw down onto form plywood (ordinary plywood and even particle board work, but they don't withstand as many castings). I always cast with coarse or fine concrete. Then I cut out and place in the reinforcing mesh, and if I remember, I oil the mold with regular cooking oil so the slabs release more easily. I usually smooth the surface with a steel trowel and create a slight slope from the center so water runs off; this is the surface that is the top side, I don't turn them over. They usually dry under plastic for 3 days when it's 20 degrees warm, with watering each day before I remove the form. If you want beveled edges right away, apply latex caulk or silicone to the edges of the mold, I usually bevel with an angle grinder afterward. Then I often diamond polish certain slabs once they are completely dried out.
If you are going to cast 1x1 meter large slabs, you should increase the thickness a bit to at least 6-8 cm and have both reinforcing mesh and a couple of thicker reinforcing bars in them, otherwise, they will crack if you jump on them. If you are going to cast a lot, order a bulk bag of 1 ton of dry mortar as it is more convenient, in my opinion, just shovel it into the concrete mixer. Approximately 160 kg of dry mortar will be needed for a 100x100x8 cm slab.
Unfortunately, I must inform you that it won't be cheaper to cast yourself when you account for everything (concrete, battens, screw form plywood, reinforcement, tools, and time) compared to the cheapest concrete slabs you can buy at regular hardware stores, but you are guaranteed to get unique slabs that last longer than the bought ones.
My standard slab is usually 40x40 cm, just as you thought, I build a frame of 45x45mm battens which I then screw down onto form plywood (ordinary plywood and even particle board work, but they don't withstand as many castings). I always cast with coarse or fine concrete. Then I cut out and place in the reinforcing mesh, and if I remember, I oil the mold with regular cooking oil so the slabs release more easily. I usually smooth the surface with a steel trowel and create a slight slope from the center so water runs off; this is the surface that is the top side, I don't turn them over. They usually dry under plastic for 3 days when it's 20 degrees warm, with watering each day before I remove the form. If you want beveled edges right away, apply latex caulk or silicone to the edges of the mold, I usually bevel with an angle grinder afterward. Then I often diamond polish certain slabs once they are completely dried out.
If you are going to cast 1x1 meter large slabs, you should increase the thickness a bit to at least 6-8 cm and have both reinforcing mesh and a couple of thicker reinforcing bars in them, otherwise, they will crack if you jump on them. If you are going to cast a lot, order a bulk bag of 1 ton of dry mortar as it is more convenient, in my opinion, just shovel it into the concrete mixer. Approximately 160 kg of dry mortar will be needed for a 100x100x8 cm slab.
Unfortunately, I must inform you that it won't be cheaper to cast yourself when you account for everything (concrete, battens, screw form plywood, reinforcement, tools, and time) compared to the cheapest concrete slabs you can buy at regular hardware stores, but you are guaranteed to get unique slabs that last longer than the bought ones.