Browse Forums Paving & Concreting 1 May 09, 2009 8:38 am I've never done any concreting. I'm putting up a small garden shed - 4 mtrs x 3 metres. The steel shed is up and on four corner concrete blocks I levelled and made. I dug out a space for the doorstep including part of the wall. So's I could anchor the doorsides and protect the thin steel channel at the bottom of the door. Here we've got a soil that looks like fine reddish sand. I dug out what I reckoned was too much, when I remembered (right before my eyes) that the shed was 100mm off the ground already. So I put some back in. Then I saw that now the soil was all loose and powdery where it had been hard and compacted before I dug it out. So I tried to tamp it down with the end of my fencing bar to make it hard. Then I remembered that you slump sand and compact it by adding water. So I added water. And got mud. Which is slowly drying. Two days old now. So here's the questions: Can I pour concrete on this mud? Is it compact enough? Did I do the right thing (seems doubtful) ? What should I have done? regards, ab Re: Compacting Fine Soil before Concreting 2May 09, 2009 11:06 am all concrete should be on a compacted crushed rock base min. 50mm - 60mm depth after compaction Da Vinci Outdoor Living Architectural landscaping http://www.davincioutdoor.com Re: Compacting Fine Soil before Concreting 3May 10, 2009 8:04 am So I should dig it out again and get some crushed rock and put it in? Does it really matter for such a small job? About 0.8m x 0.4m x .15m, just a step for the doorway of the shed, as I said. When I come to pour the whole slab I guess I'll have to do a good job. Crushed rock under it all? Then plastic sheet? Then mesh? Then concrete 100mm ? regards, ab Re: Compacting Fine Soil before Concreting 4May 10, 2009 8:37 am Clear out the soft soil, and mud.... And make sure you use some reo in the concrete.... Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: Compacting Fine Soil before Concreting 5May 10, 2009 10:07 am I'll do that. What sort of reo will suffice? I'll have to dig out the floor a bit more after reading your advice. I've allowed for 100mm. If I'm going to have to put gravel down I'll need to dig out 50mm or so to allow for the gravel I guess. It all seems too much for a dinky little 4m x 3m shed but I guess that's just my ignorance. This is just what it takes to do a proper job of making a concrete floor? We've just moved into this property. There's an area in the backyard of about 6m x 4m that seems built up and levelled and comprised of some sort of white crushed stuff. I think it must have been a pad that a previous owner had a shed on. People hereabouts often build sheds with no floor or just some crushed stuff. Would this stuff be okay to put under my concrete? At least for this doorstep thing? And 'reo in the concrete' even for this small doorstep? I put corner slabs in to stand the shed on and there's no reo in them. No gravel under them, either. They're about 400mm square and have the central part dug down about 300mm. They did have plastic sheet under them and were covered for three days after pouring. I can't imagine it but I might as well ask while I've got the benefit of your advice - they'll be okay for their job? They won't just crumble away or something? regards, ab :0 Re: Compacting Fine Soil before Concreting 6May 10, 2009 6:07 pm Reo, just use some SL52... Or whatever you can get from your local... Do the job once, and it'll last you a lifetime. It'll never structurally fail then! I'd say they used crusher dust under an old shed, so yes this is perfect for under your new shed slab... As you put it down, give a light sprinkling of water to help it compact... Your pad footings sound ok, but what type of mix did you use? Try and tie your new slab into these... Electrical Engineer... Don't hold that against me... And keen owner builder... Mainly the building part!! Re: Compacting Fine Soil before Concreting 7May 10, 2009 9:09 pm SL52 ? Meant nothing to me, did a quick google and the first hit I got was your reply in this forum thread!! And didn't get any more information. I'll find out tomorrow at the hardware store I guess. For a mix I used sand and gravel readymix from a local gravel and dirt and whatever supplier and he advised me to use it 1:5 with cement, so I did that. It is not mixed up too good - I mixed it in a wheelbarrow and was probably a bit lazy with the mixing. It gets tiring, eh? I've now got an old concrete mixer that I need to fix up a bit. Move and re-attach the motor. Put a belt on. Raise it off the ground enough to get a wheelbarrow under. Then I'll use it to make the slab. Using all this valuable information you're giving me. Thanks How will I tie the slab into this doorstep and the footings? How will I tie the slab into itself? I mean I intend to pour it in sections. Three, I think. One along one wall, one down the centre and one along the other wall. Outside sections will be 4.2m x 1.1 and the centre 4.2m x 1m. I'll take the slab out 100mm past the wall. I figured it'd be too much for me to do in one hit. Re: Compacting Fine Soil before Concreting 8May 12, 2009 10:49 pm 4 x 3 x .1 = 1.2 cu mtrs ( about 12 cu ft ) Small mixers are about 2.2 cu ft the larger are about 3 cu ft. the mix should be 3sand 2agg 1cement Use a bucket to measure ingredients since it is all mass not guess...K? Not too wet Where you are coming from is where you are going to... Re: Compacting Fine Soil before Concreting 9May 20, 2009 11:56 am OK, I've got the mixer fixed and working, I hope, the test is going to be if it does a job or not. I'll pour this doorstep today. I haven't got any reo for it. Do I need reo in a doorstep? 1.2m x .5 x .1 ? I've got a bit of pig fencing is all. I'll stick that in. Some people say to me use chicken wire or anything you've got. Is that right? There's a hell of a difference between chickenwire and the reo you mention: F52 they call it around here. regards, ab did you builder accepted that for final design ? our builder want to do final soil test after demolition as soil gets disturbed , pre build we got P with H1 but post… 8 7506 Just get as close as you can without hitting the posts. Once you are close to the edge of the path the chance of cracking is minimised. 7 11452 That could be a piece of timber that was mistakenly attached to the formwork. Any reduction in concrete section is a concern. I would get it checked by a qualified… 3 2451 |