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Posted: Mon Jul 09, 2007 10:20 pm
by bentleydale
If building a pond above ground by using blocks would you only need to build it one block thick?
Posted: Mon Jul 09, 2007 10:47 pm
by IanMelb
It may really depend on the volume of water.
There's probably an inverse cube rule going on there with regard to how much pressure is exerted on the blocks in relation to the volume of water that they are holding back.
If twere me (and bear in mind that I'm talking about my hobbyist/diy opinion) and I had to do it with blocks then I'd make sure they were all tied together and banded round the outside with something reasonably meaty....
Posted: Tue Jul 10, 2007 12:01 am
by lutonlagerlout
225mm concrete blocks would be best with some kind of liner,or even better engineering bricks,102 mm block work could fail
LLL
Posted: Tue Jul 10, 2007 6:54 am
by IanMelb
Would it need tying together then LLL?
Posted: Tue Jul 10, 2007 5:02 pm
by lutonlagerlout
why tie together 2 skins when you can build one,faster and cheaper,blocks weight 40 kg s though 
cheers LLL
Posted: Tue Jul 10, 2007 6:58 pm
by Ted
http://www.textileconcreteconsultants.c ... ining.html
I use this stuff when lining a pond.
You have to buy it in South Africa though.
Any polypropylene mesh will do as concrete/mortar reinforcement. Loads of medical supply companies will sell it cheaply/free.
But CemLam, the waterproof stuff, is hard to get in the UK as doctors generally don't need it. Is specialist stuff...
Posted: Tue Jul 10, 2007 10:53 pm
by IanMelb
lutonlagerlout wrote:why tie together 2 skins when you can build one,faster and cheaper,blocks weight 40 kg s though
cheers LLL
Ah, what I meant was some kind of strapping to stop the water pushing the blocks 'out' - a bit like the metal hoops on a barrel.
I was envisiging a fair mass of water behind each block, although not knowing the volume of water involved and how many courses of blocks are planned kind of makes it difficult to work out the forces.
Most dams have wide bases, I believe that's for two reasons, stability wrt height and strength to stand up to the water pressure behind - I know it's a pond not a resevoir but as I've mentioned elsewhere, I'm very much a belt and braces bloke and I tend to over-engineer most of the things I'm unsure about. 
Posted: Sat Jul 14, 2007 10:54 am
by seanandruby
As long as there's not a tsunami occurring inside it should stand up a? :laugh:
Posted: Sat Jul 14, 2007 12:15 pm
by matt h
one mate of mine tried to put an ordinary preformed pond above ground with only timber framed support. it lasted about 3 weeks. we drained it, repaired it and built a single block wall 4 blocks high around it and then filled around the pond in sharp sand....worked a treat.. only problem was some bloody heron ate all his koi!.Some people just dont have the luck. I have the formula for calculating the stress loads of water volume somewhere, i'll dig them out
Posted: Sat Jul 14, 2007 12:18 pm
by matt h
Ted wrote:http://www.textileconcreteconsultants.c ... ining.html
I use this stuff when lining a pond.
You have to buy it in South Africa though.
Any polypropylene mesh will do as concrete/mortar reinforcement. Loads of medical supply companies will sell it cheaply/free.
But CemLam, the waterproof stuff, is hard to get in the UK as doctors generally don't need it. Is specialist stuff...
excellent material isnt it. Now use the epdm sheet on flat roofing projects as well. Lasts far longer than traditional three layer felt