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Thread ID: 120161	2011-08-28 02:29:00	Laying concrete	Nomad (952)	PC World Chat

Post ID	Timestamp	Content	User
1226422	2011-08-28 02:29:00	We have a small area in the backyard that we are planning. In the past we got builders mix (a mixture of sand and gravel) and concrete powder but the finish was stoney. I read off the net and a brochure says 3 part gravel, 2 part sand and 1 part concrete but the guy at Bunning suggested builders mix and concrete or just the premixed stuff. So I like some help in this :D Maybe we got the ratio wrong in the past, maybe we need a proper tool to wipe the concrete so it is smooth :confused: :thanks:	Nomad (952)
1226423	2011-08-28 03:00:00	If its stones you may have worked it to much - have a read of This article (www.mitre10.co.nz) Number 9 gives ways of the finish. mixing Guide (www.mitre10.co.nz) When I have done the odd job I have always brush finished it, bit of grip in wet conditions then.	wainuitech (129)
1226424	2011-08-28 03:43:00	The right stuff to use is called Conag and you mix 6 parts conag to 1 part cement, I spent half my working life it seems laying concrete for a living. You can get conag by the scoop and it works out way cheaper than buying bags and a bag of cement should be around $15-17. The premixed stuff always has too many stones in it	gary67 (56)
1226425	2011-08-28 05:24:00	Mixing concrete is an art. The secret is do it with as little water as possible, just keep adding SMALL amounts of water, letting it work into the mix until the mix JUST starts flowing instead of breaking up. Take your time. If your mix is good it will pour out and look like a cow pat, keeping en even consistency right through. rake it out to fill your boxing, and screed off with a straight length of timber. If it is a bit sloppy on top leave it till it starts to dry before troweling. The idea of troweling is to cause the bigger parts of the aggregate in the concrete to be pushed down slightly so they don't stick up when the concrete dries and shrinks slightly. Plus you get a fine finish from the smaller particles that are left. Don't over trowel, this will make for a weak surface. As to premix verses builders Mix and cement, my experience is that premixes tend to have a smaller\finer range of aggregates in them. This makes them suitable for patching and fill in work and small jobs that don't require a lot of strength A good builders mix will have a wider range of aggregates resulting in a stronger concrete. Make sure you have a well compacted base as concrete without reinforcing has a weakness to break underneath if there is not adequate support. Sorry if this is more information than you asked for!!	PPp (9511)
1226426	2011-08-28 06:46:00	...Mixing concrete is an art... Quite right - sorry Nomad, but I think you should get help from someone who has done it before. (and I don't mean help via the Internet)	decibel (11645)
1226427	2011-08-28 08:38:00	When I have done the odd job I have always brush finished it, bit of grip in wet conditions then. A paint roller can make quite a nice finish.	mikebartnz (21)
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