Browse Forums Landscape & Garden Design 1 Mar 21, 2011 1:58 pm Hi everyone, what an excellent and helpful forum this is. I just had a few quick questions regarding concreting in twelve CCA treated pine sleeper posts for a retaining wall, and was hoping somebody could lend some advice. - How much concrete should I expect to need for each sleeper post? The sleepers are 200mm x 75mm and will be buried 600mm in the ground. - Could the rapid set concrete be an option for this? I have no experience with concrete at all - is it likely to start hardening before I can get it out of the wheelbarrow and into the hole? Ideally I'd love to do the whole wall as quickly as possible while I have a mate there to help me! - If the rapid set is not a good idea, how long would we need to wait for the normal stuff to harden enough to start attaching the horizontal sleepers? Thanks in advance for the help Re: Retaining wall - questions on concreting sleepers in gro 2Mar 21, 2011 2:28 pm I did a wall with the exact same sleepers and depth and generally I used between 1.5-2.0 x 20kg bags. So for 20 holes maybe 35 bags. The stuff I used was rapid set premixed concrete which I simply dumped into the hole around the post and poured water in and let the water make its way through the concrete and harden. I wasn't going to mix concrete in a wheelbarrow for 28 holes and that is the way fencers do posts so I figured if it works for them then fine. You generally get about 15 minutes to adjust the post a little before the concrete is set - you can only adjust it by maybe 10mm so its best to get the post as close to the right measurement/angle before you pour the concrete. Re: Retaining wall - questions on concreting sleepers in gro 3Mar 21, 2011 4:02 pm Just like Mozzie has said. Rapid Set goes in the hole dry and you add the water after that. It's not advisable to mix rapid set in a wheelbarrow as it is not designed to be mixed in that way. Rapid set for what you want to do will be fine. I like the ordinary pre-mixed concrete but that's just a personal choice and the fact that I'm working on my own and I can only do a certain amount per each day. I have found that my posts for my wall, concreted in with non-rapid set are fine the next day to begin the attaching of the horizontals. Hope this helps. Rgds Leonard. Re: Retaining wall - questions on concreting sleepers in gro 4Mar 21, 2011 4:09 pm Thank you both for the replies - definitely helpful stuff. Given that time will not be on our side, I'll probably go with the rapid set so we can get on to the next stage quicker. Can you give me a rough idea on how much water you'd need to mix with one of the 20kg rapid set bags? Is it critical to get exactly the right amount? Otherwise I guess you could just pour the dry mix in, then stick the hose in the hole and squirt some water in, and then basically just give it a stir with a stick to make sure it all mixes together? One more question - did you guys paint the cut end of the sleeper with something to stop it rotting while in the ground? I'm worried about exposing the cut surface to moisture, but the guy at the hardware said the CCA treatment goes all the way through and no need to treat it again after cutting. Thanks again. Re: Retaining wall - questions on concreting sleepers in gro 5Mar 22, 2011 8:39 am It should tell you on the bag how much water to use. Re: Retaining wall - questions on concreting sleepers in gro 6Mar 22, 2011 8:40 am The guy at the hardware store is an idiot and doesn't know how the treatment works. It seal like an envelope and doesn't sink in very far at all. Yes you should re treat with the same or a bituminous paint. Re: Retaining wall - questions on concreting sleepers in gro 7Mar 22, 2011 9:39 am Ah, I suspected that was the case. Glad somebody could set it straight. Re: Retaining wall - questions on concreting sleepers in gro 8Mar 22, 2011 12:12 pm yep - I'm painting my cut ends with some stuff a mate gave to me which is a black bituminous paint he didn't need anymore. As for how much water to use for the rapid set - yep check the bag for instructions but you have pretty much got the idea by giving it a squirt in the hole and a poke with a stick to ensure it is mixed thru. Good luck. Not sure what council area you are in. Some LGA's allow zero lot retaining walls. This usually occurs in greenfield developments but not often in established areas. You… 1 8213 4 11184 Thank you again Simeon.. I will call my certifier for that. Have a good day 4 5141 |