Browse Forums Paving & Concreting 1 Aug 13, 2010 11:38 am Hi everyone, I am in the process of planning my retaining wall. I have chosen to use the TJ Imports stoneblok system for retaining walls. They look like this: http://i484.photobucket.com/albums/rr209/wonderland69/stacker2.jpg http://i484.photobucket.com/albums/rr209/wonderland69/stacker1.jpg The plan is to lay these interlock blocks on the concrete footing, as well as concrete core fill it. Now as I've never attempted to do a concrete footing before, this will be my first time. I've done some research as to how to set it all out but need expert advice on whether this is the right way. Also, I do need clarification on certain things . The retaining wall will be 8m wide by 1m high. I was thinking of digging a trench for the concrete footing which will be 300mm x 300mm. Is this wide enough for the hight of the retaining wall? I will need to put those reinforcement bars in the concrete. I was planning on using N12 at 300mm apart. Is N12 strong enough for this project, and is the spacing of 300mm apart too close or too far or perfect? Also, I would like to know how far into the base does the bars have to go into? As the bars will be stick up around 1m high, and those stoneblocks are layed like brickwork, it will come to a point where i would have to bend the bars so that it fits in the gap of the blocks. Are those bars very flexible to bend? How have people managed to overcome that? And one last question, I will need to pour concrete into the blocks, what type of concrete would I need? Can I just use those readymix ones you buy in 20kg bags from bunnings? Or do i need to get those high mpa ones from somewhere like Mentone Pre-mix? I will be using 20mpa concrete for the concrete footing which I will buy from Mentone, but would I need to use the same for the concrete fills of the blocks? Sorry about all the questions, thanks everyone for their advice!! Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 2Aug 13, 2010 11:45 am Re: DIY concrete footing for retaining wall 3Aug 13, 2010 11:57 am Thanks Nathan for your reply. I have spoken to my council and they said that unless the retaining wall is over 1m high, I dont need an engineer. The wall isnt exact 1m high, its more like 900mm. Also, the stoneblock retaining system is engineer approved. Sorry but I cant seem to understand the drawings that much, are you able to break it down for me? Thanks. Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 4Aug 13, 2010 12:10 pm Ok we start with the digging of the trench 750x300? Get the reo cages made up. M12 not to hard to bend with tools. M16 need to either heat or have them made up. Onesteel can make up the cages for you (Brisbane, don't know who does it down south. Reo starter bars to be coming out at the top. Pour footing. Then the blockwork gets put up, reo horizontally as you go wiring them to the verticals. Once the blocks are at 1M, pour concrete to fill, don't know what type of concrete sorry. Lag the back of the blocks facing the soil with a tar like substance, cover in a type of plastic sheeting that I dont know the name of. Gravel a small bit at the bottom, lay in AG drain. Cover in gravel. Done! Re: DIY concrete footing for retaining wall 5Aug 13, 2010 12:40 pm Thanks heaps Nathan!! Ok, you're going to have to bear with me here, sorry! What is a rego cage? How wide should the N12 starter bars be? I heard that they need to be 300mm apart. But on the diagram, it says 400mm apart? What is the right distance? With regards to the back of the bricks, I was going to use geomat? Is that sufficient? How much would the geomat cost? Thanks. Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 6Aug 13, 2010 4:56 pm wonderland Thanks heaps Nathan!! Ok, you're going to have to bear with me here, sorry! What is a rego cage? How wide should the N12 starter bars be? I heard that they need to be 300mm apart. But on the diagram, it says 400mm apart? What is the right distance? With regards to the back of the bricks, I was going to use geomat? Is that sufficient? How much would the geomat cost? Thanks. Reo cage is this: Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Showing starter bars: Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Google Retaining wall footing for a good look at lots. Don't know how wide the N12 should be sorry. Go 300 to be sure, over engineer to be safe. Sorry I can't advise you on Geomat, I don't know what it is. The stuff on the back of all of our walls looks like cardboard made from plastic. Re: DIY concrete footing for retaining wall 7Aug 13, 2010 5:33 pm @ Nathan - The cardboard looking plastic is 'coreflute'... normally a protective barrier for a waterproof membrane Geo mat is a sediment barrier... to stop your drain blocking up. Where you are coming from is where you are going to... Re: DIY concrete footing for retaining wall 8Aug 13, 2010 5:37 pm @nathan, thanks for showing me the pictures and trying to explain. @one_artisan, with regards to the matt for drainage, what should i buy? Some people say geo fabric, others say garden fabric. What is a garden fabric? Also, when trying to line the fabric, am I suppose to protect the back of the wall from the screening rocks, or am I suppose to protect the rocks from the backfilling dirt? Not sure where i'm suppose to put the mat. Thanks for the help Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 9Aug 13, 2010 5:51 pm Sorry not my claim to fame.. but garden matt could be considered weed mat Just remember it is hard to make assumptions without having a full idea of the site. IE If you will be paving/concreting the retained area etc. sounds like it will be a garden. That being the case you will want to parge the back of the wall. Parging is appling a waterproof membrane to stop water entry into the wall substrate... Yes I know it is concrete... poorly compacted concrete can be very absorbent. and is what usually happens on infills. back fill a 100mm lay in your drainage pipewith fall to the outlet side then top with more blue metal 100mm ...then cover with matting material then cover with earth. Where you are coming from is where you are going to... Re: DIY concrete footing for retaining wall 10Aug 15, 2010 9:05 pm @onc_artisan. LOL sorry but I'm still abit confused. I was going to put geo frabic/garden fabric all the way down the wall. Would that be waterproof? And you are correct, I will be putting turf on the retained area. Thanks Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 11Aug 15, 2010 10:13 pm Definately NOT waterproof Where you are coming from is where you are going to... Re: DIY concrete footing for retaining wall 12Aug 15, 2010 10:15 pm Ok so what should I use which is waterproof? thanks Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 13Aug 15, 2010 10:32 pm A flexable jointing cement on the joins(embedded in soil) and a liquid applied membrane bridge. Where you are coming from is where you are going to... Re: DIY concrete footing for retaining wall 14Aug 15, 2010 10:38 pm Do you mean that the cement which I will use to join the blocks together, I need a flexable jointing cement? A liquid applied membrane bridge? Wow what is that? I will I be able to go to Bunnings and ask them for this? sorry! Idiots are fun, that's why there is one in every village! - Dr. House - Re: DIY concrete footing for retaining wall 15Aug 15, 2010 10:50 pm sika flex pro for the jointing and ask for a liquid waterproofing membrane. Do 3 coats per the directions Where you are coming from is where you are going to... there is a standard besser block wall pdf somewhere online with footing sizes, also have a look at dincel. 1 2883 Versaloc is a mortarless besser block system that still needs a properly engineered footing. If you just do a 400x200 footing it will fail in time. At 17m long you need it… 1 15629 yep sounds good make the footing bigger to to allow for the pipe in the middle 3 7298 |