- Joined
- Sep 14, 2013
- Messages
- 6,288
- Reaction score
- 5,068
- Location
- Cincinnati, Ohio
- Hardiness Zone
- 6 A
- Country
I don't have a concrete pond, but I've read about monolithic pours and XYPEX to seal the concrete.
Rebar for concrete
- Thread starter Mark in Poole
- Start date
I have to correct my self a little, the company is Pond Armor, the product is pond shield epoxy.
They are based in California, not sure if they ship to overseas.
http://www.pondarmor.com/
They are based in California, not sure if they ship to overseas.
http://www.pondarmor.com/
Are you building a rectangular pond with vertical 4 foot sides? Are you planning on using block or forming and pouring the concrete? Mix it yourself or have the concrete delivered? Is your soil clay? sand?
No Paul, I intend the pond to have curved sloping sides. I will also mix the cement myself, buy in bulk at trade and it takes as long as it takes.
The flaw with concrete, its brittle. It's big test is the plate of ice that can form in winter, trying to expand 10% with freezing. Rebar adds strength to the shape. Angling the sides can deflect the pressure so the plate slides rather than snaps... Mix shredded plastic into the concrete mix, that will increase its resistance to cracking, shattering...
If your pond is a modest size and you are ok with covering it for the winter months you don't have to worry about a thick ice plate forming, at all... Even going so far as to say you can skip the rebar and thick concrete, totally
If your pond is a modest size and you are ok with covering it for the winter months you don't have to worry about a thick ice plate forming, at all... Even going so far as to say you can skip the rebar and thick concrete, totally
Thanks adavisus.
I don't see ice as a major issue due to where I live. I have a very small pond at the moment and it has had a thin layer of ice once in the past 2 years. I think taking all on board though I would still use rebar, it isn't expensive in comparison to the hassle of doing it again.
The guys in the building trade I have spoken to have told me to add wizard fibre. I assume this has a similar effect as shredded plastic?
I don't see ice as a major issue due to where I live. I have a very small pond at the moment and it has had a thin layer of ice once in the past 2 years. I think taking all on board though I would still use rebar, it isn't expensive in comparison to the hassle of doing it again.
The guys in the building trade I have spoken to have told me to add wizard fibre. I assume this has a similar effect as shredded plastic?
There's probably some variants on the market for reinforcing cement with shredded hdpe plastic. They would all work well to reduce the risk of concrete from snapping under stress. It is a better solution than rebar, as it does not corrode. You have to set rebar with 2" cement covering it to reduce corrosion rusting the metal...
That is a lot of hard work and cost, laying 5" thick concrete... A 3" layer of concrete is a lot less work than 5" thick to do, still with the risk of rebar rusting...
Lay your hands on a shredder and a load of tough plastic feed bags and you can chug your own plastic shred strip to order...
Yup close to the coast your risk of a prolonged hard freeze shattering a pond structure is much lower. That risk can be eliminated by putting a cold frame over a pond, completely. If you know you can see a polar vortex bearing down on you....
How long does it take to prop up some roof lathes across a pond and throw a sheet of 6ml clear plastic across, weight it down in place with blocks. Not long at all.You can do that the day after the storm blows in and everything calms down for the big freeze.
Maybe, once in ten years you get a serious hard freeze lasting a week, that would be the one to worry about when the ice gets more than 2" thick
That is a lot of hard work and cost, laying 5" thick concrete... A 3" layer of concrete is a lot less work than 5" thick to do, still with the risk of rebar rusting...
Lay your hands on a shredder and a load of tough plastic feed bags and you can chug your own plastic shred strip to order...
Yup close to the coast your risk of a prolonged hard freeze shattering a pond structure is much lower. That risk can be eliminated by putting a cold frame over a pond, completely. If you know you can see a polar vortex bearing down on you....
How long does it take to prop up some roof lathes across a pond and throw a sheet of 6ml clear plastic across, weight it down in place with blocks. Not long at all.You can do that the day after the storm blows in and everything calms down for the big freeze.
Maybe, once in ten years you get a serious hard freeze lasting a week, that would be the one to worry about when the ice gets more than 2" thick
Last edited:
Thanks again adavisus that is pretty reassuring, I have read a lot about concrete cracking even as it dries. It seems to me though if you follow the advice of the experts then it is avoidable.
I totally agree on watching the weather forecast as well, better to avoid the problem than try to correct it.
I totally agree on watching the weather forecast as well, better to avoid the problem than try to correct it.
- Joined
- Nov 11, 2010
- Messages
- 4,071
- Reaction score
- 4,025
- Location
- Chicago Area
- Hardiness Zone
- 5b
- Country
I would totally avoid mixing the cement yourself as the quality will not nearly be the same as what you can get from a truck. Adding some rebar will help reinforce the concrete but you need to know how to tie it together properly and the proper size to use. Also you can order the cement with a fiber addititve that will greatly add to the strength. The cost extra per yard is pretty minimal. This may sound like a stupid queston but were you planning on making the whole thing from cement or were you going to use rock and gravel and pour cement around it? Larger concrete structures are rarely made from 100% cement. If you ever want to get rid of it it will be a horrible experience to demo a solid concrete pond. Also are you planning on putting any footings or piers in the ground? If you don't it may literally sink on you or tip. Also if you are planning one big pour you better have all the forms reinforced so they don't start moving on you. You might want to consider pouring the walls first and the rest of it in a second pour. Also re DIY. I'm in construction. i have seen a lot of diy projects. It's very unusual they are the same quality as a professional, but if you are happy with the results that's all that matters. I would never hire a profesional to build myself a pond. I know they are better at it but there is a lot of satisfaction in making something yourself!
The first mix will be made with rubble followed by two coats of render. I will use 10mm rebar.
I would also agree that many diy jobs are a total bodge. I don't work like that though and my standards are extremely high. I think one of the key factors is to know your limitations. I for example am rubbish at carpentry so that is one thing I always pay for.
When I left the forces through interest I went to building college so although I would never clsss myself as a pro I am qualified. (Not in ponds)
I am pretty confident that my knowledge there mixed with the vast experience of the lovely people on here will see me through ok.
I HOPE!!!
TY.
I would also agree that many diy jobs are a total bodge. I don't work like that though and my standards are extremely high. I think one of the key factors is to know your limitations. I for example am rubbish at carpentry so that is one thing I always pay for.
When I left the forces through interest I went to building college so although I would never clsss myself as a pro I am qualified. (Not in ponds)
I am pretty confident that my knowledge there mixed with the vast experience of the lovely people on here will see me through ok.
I HOPE!!!
TY.
A practice mix laid across the base of the pond would be a good start, to create an area sound to walk about on when you do another mix to lay the sides. Biggest chore is just moving the materials up to the pond... The shorter the distance between the mixer and the job the better, humping wet cement about is, good exercise
Mark, I like DIY too, for the experience if nothing more. And you certainly sound like you're doing good research and know what you're getting into so you have every chance of success I'd say.
Is rebar needed? Nope. But as Adavisus said, I think, it's an engineered thing. No rebar normally means thicker concrete. But a lot more.
Research the fiber additives more, my understanding is they're used more in thinner applications and not useful in thicker but not sure.
It is true many (maybe most, seems like almost all) DIY concrete ponds fail...and in spectacular fashion often. Removal being even more work and $$$ than the "build". But in all cases I've read about and seen the cause is always the same. For some reason people think they can engineer such a build with absolutely no experience and no research.
The best source of info imo is from concrete swimming pool construction, not ponds. Professional built ponds in the US are built exactly the same as pool with just the drain/skimmer stuff being different. Much more info and many more builds. Lots of research has gone into pool construction to get the lowest cost AND the most reliable.
From that there are a couple of things DIYers seem to miss. Most importantly pools are built so they could be pulled out of the ground and rolled down the street and not crack (kind of). Meaning they do not rely very much on ground support. Should one end settle even a little there is tremendous stress created. By making the entire structure basically self supporting is help the whole structure to settle, move, as a unit. Most DIYers seem to think the ground provides the structure so a little concrete to "waterproof".
The second thing is that the thickest part, and the most rebar, is in the collar. The bottom is the thinnest. Kind of the reverse of what most people intuit.
Here in the US I've only seen pools built with rebar...a lot of rebar. My assumption is that's the cheapest and most reliable method. I like thinking out of the box and creating my own designs, but I don't need to be an idiot either.
As far as not using rebar the only example I can think of are driveways. In San Jose CA building code does not allow any steel and instead the concrete must be 6" thick. I'm not 100% sure why, could be they want removal to be easier.
For sure proper construction with rebar doesn't have any problem with rusting or ice and cracking isn't a problem given the millions of concrete pools that have been in use throughout the world for many years.
I'd be very careful with DIY websites showing pool builds. These almost always show the build and holding water the first day. Given the construction these must certainly fail later but of course people very rarely post their own failures. Sites make it sound great.
And I agree 100% on seeing liner and folds. I don't want to look at that, algae or not. And folds make cleaning a bit more difficult. However, I also like EPDM a lot. Hard to mess that up and cheaper than concrete. So what I do is lay the liner and then concrete over the liner. Basically a stucco (render) veneer over the liner. Only has to be 1/2 to 1" thick and no steel. Actually I normally mortar rock over the liner.
Solves all my liner issues while staying cheaper and easier. I like the look of rock more than even concrete but this can result in something hard to tell from a solid concrete pool/pond. Makes cleaning much easier (no folds) and you or dogs can walk around in the pond without fear of liner damage. Also very easy to remove, change, etc...
You can also use cheaper poly liners which the rock/mortar protects.
My web page http://www.waterbugdesign.com/pond/rock_bottom_pond.html
Is rebar needed? Nope. But as Adavisus said, I think, it's an engineered thing. No rebar normally means thicker concrete. But a lot more.
Research the fiber additives more, my understanding is they're used more in thinner applications and not useful in thicker but not sure.
It is true many (maybe most, seems like almost all) DIY concrete ponds fail...and in spectacular fashion often. Removal being even more work and $$$ than the "build". But in all cases I've read about and seen the cause is always the same. For some reason people think they can engineer such a build with absolutely no experience and no research.
The best source of info imo is from concrete swimming pool construction, not ponds. Professional built ponds in the US are built exactly the same as pool with just the drain/skimmer stuff being different. Much more info and many more builds. Lots of research has gone into pool construction to get the lowest cost AND the most reliable.
From that there are a couple of things DIYers seem to miss. Most importantly pools are built so they could be pulled out of the ground and rolled down the street and not crack (kind of). Meaning they do not rely very much on ground support. Should one end settle even a little there is tremendous stress created. By making the entire structure basically self supporting is help the whole structure to settle, move, as a unit. Most DIYers seem to think the ground provides the structure so a little concrete to "waterproof".
The second thing is that the thickest part, and the most rebar, is in the collar. The bottom is the thinnest. Kind of the reverse of what most people intuit.
Here in the US I've only seen pools built with rebar...a lot of rebar. My assumption is that's the cheapest and most reliable method. I like thinking out of the box and creating my own designs, but I don't need to be an idiot either.
As far as not using rebar the only example I can think of are driveways. In San Jose CA building code does not allow any steel and instead the concrete must be 6" thick. I'm not 100% sure why, could be they want removal to be easier.
For sure proper construction with rebar doesn't have any problem with rusting or ice and cracking isn't a problem given the millions of concrete pools that have been in use throughout the world for many years.
I'd be very careful with DIY websites showing pool builds. These almost always show the build and holding water the first day. Given the construction these must certainly fail later but of course people very rarely post their own failures. Sites make it sound great.
And I agree 100% on seeing liner and folds. I don't want to look at that, algae or not. And folds make cleaning a bit more difficult. However, I also like EPDM a lot. Hard to mess that up and cheaper than concrete. So what I do is lay the liner and then concrete over the liner. Basically a stucco (render) veneer over the liner. Only has to be 1/2 to 1" thick and no steel. Actually I normally mortar rock over the liner.
Solves all my liner issues while staying cheaper and easier. I like the look of rock more than even concrete but this can result in something hard to tell from a solid concrete pool/pond. Makes cleaning much easier (no folds) and you or dogs can walk around in the pond without fear of liner damage. Also very easy to remove, change, etc...
You can also use cheaper poly liners which the rock/mortar protects.
My web page http://www.waterbugdesign.com/pond/rock_bottom_pond.html
Troutredds
You can call me Red
- Joined
- Jul 17, 2013
- Messages
- 970
- Reaction score
- 2,587
- Location
- Seattle area
- Hardiness Zone
- 8a
- Country
Our pond is concrete (shotcrete), ten inches thick, with a lot of structural steel. Our (pool) contractor installed a hydrostatic relief valve in the bottom drain to keep ground water pressure from popping the pond out of the ground, if we ever drain it (probably overkill). It's only been four years but so far so good. Here's some pics of the process, @Mark in Poole. I've posted a couple of these previously, but not together:
Last edited:
There are some great replies there thank you. I have just got in from work and I need to go back out so I will reply in full tomorrow. I had to respond I hate appearing rude. 
Thanks guys some very interesting reading.
Thanks guys some very interesting reading.