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    • CommentAuthormarsaday
    • CommentTimeMay 2nd 2017
     
    This summer i will be doing 21m of strip foundation for a single story ext. I will have to dig out 800mm x 600mm depth and width i think, but i don't think i will need to fill fully with concrete.

    I have a feeling a depth of 400mm will be ok. BC will let me know what is what when planning comes through.

    I will be doing most of the work on the building, so no labour costs to factor in.

    Firstly what is the likely depth of concrete i will need ?

    If it is 400mm, then that = 5cubm of concrete. This = (i think) 10T of ballast.

    Secondly i am thinking about self mixing with a mixer as it means i won't be under any rush when the mixer comes and i may be on my own. So if i barrow the ballast round the back the day before i can mix next to the area and pour over the day. Less stress etc.

    Does this sound like a bad idea ?
  1.  
    If your cement mixer has a capacity of .1 cubic metres, you'll have to mix 50 loads. Could keep you busy. Might be feasible with a pan mixer though.
    • CommentAuthormarsaday
    • CommentTimeMay 2nd 2017
     
    I am going to buy this mixer for the whole build (brick work etc)

    http://www.screwfix.com/p/134-ltr-concrete-mixer-230v/10107

    I am leaning towards the self mix route as i think i will be under too much pressure to get the concrete off the wagon and in the ground. I will def be in a position where i am shovelling the concrete off the drive into a barrow and so this will be tough going.
    • CommentAuthortony
    • CommentTimeMay 2nd 2017
     
    I would keep moving the mixer round the trench and tip it straight in all the time use a water butt at a central point and learn the perfect amount of water needed. water, 3 ballast, 1/2 bag cement then rest of ballast.
    • CommentAuthormarsaday
    • CommentTimeMay 2nd 2017
     
    I think i can do 21m in a day no probs. Certainly mixing 6T ballast is no issue.

    Would i have any issues with the concrete going off too quick ? I imagine i will be levelling one line of concrete and then onto the next. I have 4 lines of concrete to do; the two sides, the front of the extension and then another wall which will divide the utility and main room up.
    • CommentAuthorjfb
    • CommentTimeMay 3rd 2017
     
    can a lorry pour straight in to the trench or would it need a pump to get there? (or barrows!)
    If you could tip straight off a lorry into the trench I would do that.
    • CommentAuthorcjard
    • CommentTimeMay 3rd 2017
     
    You can get self levelling, self compacting concrete (Lafarge do it as part of their gyvlon range), at a price premium of around 50% over the per-cube price..

    21m of foundations at a 150mm concrete depth and .5m width is around 1,6 cube so you're looking at maybe £150 in standard concrete and £250 in self compacting - not much more than the cost of adding labour help to spread normal concrete

    As others have said, if you can get the wagon (and try for one of those little mix-it-on-site ones where they just charge you for what you use) to the trench, then just ask the driver to runny it up a bit and pour it straight in, then pull it with a rake. if you've got it circa thick porridge consistency it'll flow to where you want it with a bit of help. You don't need to be spot on with your levelling either; +-25mm variations can be taken up with the blockwork above as you come out of the ground and you should be ale to get it more level than that with some basic pegging out and massaging it with a rake. Try and get it dumped centrally to the trench path so it flows in either direction round to the finish points - better than dumping it in one end and having to pull it all the way

    If you can't get the lorry to the trench, consider hiring a small dump truck (a local independent should charge 50 quid ish for a day) and get the lorry to pour into that

    Use mechanical assistance wherever concrete is concerned; barrowing it and/or mixing it yourself is out and out a mug's game from a physical effort/risk of injury perspective considering the paltry sums of money saved.
    Further; if mixing yourself you cannot prove to the building inspector that it's the right grade. If you have a ticket from the concrete co that you asked for C30 and they gave you C30 then that's one less headache
    • CommentAuthorMarkyP
    • CommentTimeMay 3rd 2017 edited
     
    I dont think this is the place to try and save a few hundred quid. I'd get concrete delivered to site and, if access issues, hire a dumper and driver (couple of hundred quid) to cart the concrete and tip it into the footings, you can do the raking.

    if you insist on DIY then I'd consider hiring a second mixer, one of the large capacity diesel concrete ones, to run alongside your mixer so you can keep the concrete coming at a reasonable rate. Hiring a 0.5t tracked mini-dumper would be £50 very well spent.
    • CommentAuthormarsaday
    • CommentTimeMay 3rd 2017
     
    Looks like the depth of the footing will be around 250mm and so 3 cubic meters will be needed.

    This is not about saving money but doing a good job with less stress.

    Yes ideally if i can get the truck up to the rear gate and then have his hopper feed into my first trench round the back then great, but i am not sure this will be possible. Need to ring a few companies first.

    If it is a case of dump it on the drive and barrow it in, then this is where i have the worry of it going off too quick.

    The issue about whether BC will accept my own mixing is a valid one as well. So will speak to him first.
    • CommentAuthormarsaday
    • CommentTimeMay 3rd 2017
     
    This is my drive where the mixer will need to reverse up to. I would also need to ask the neighbours about this as well.
      drive.jpg
  2.  
    Seeing the crack in the concrete will the drive take the weight of a mixer lorry without doing further damage?
    • CommentAuthorcjard
    • CommentTimeMay 3rd 2017 edited
     
    Hard to say; if the substrate is well compacted and supportive, the concrete needs to lend very little overall flexural strength. A concrete lorry with 6 cube on board will weigh around 30 tons

    Mars, if you're after doing a proper job with no stress, then don't even think about mixing it yourself. To do so is hugely physically stressful and leads to a poor job because you just can't mix tens of batches with the same consistency of getting it out of a wagon at a guaranteed spec. Add in the cost of buying the raw materials and then humping them round the back of your house with a barrow, throwing them in a mixer.. You will find it barely possible to buy the raw materials for what a cube of readymix costs (they buy in huge bulk)

    You've mentoned again "dump it on the drive" - and you've got 2 people telling you not to do this. Hire a mini dumper, get the wagon to pour into the hopper (1 ton of concrete) on the dumper, then drive it round the back of the house and tip it in the footings. 18 trips later you're done without breaking a sweat, it's mostly level and just needs pumping with sturdy rake.

    If you dump it on the driveway, you've got to shovel it up again, and this stuff is/should be the consistency of diarrhoea. Take it from someone who has built and lifted plenty; if a building material is already up, don't put it down somewhere that you'll then have to lift it up from again..
    • CommentAuthornigelm
    • CommentTimeMay 3rd 2017
     
    We used a company in manchester, the lorry turns up with 3 lads, the concrete is mixed on the fly into wheelbarows and they barrow it to where you want.

    The mix is controlled and metered so you pay for what you take.

    We had about 3 cubes in no time. The lads had huge barrows and virtually ran. Cost was the same for standard delivery ready mix and they can make any mix you want, ours was C25 with reenforcing fibres added. Top job
    • CommentAuthormarsaday
    • CommentTimeMay 3rd 2017
     
    I will look into a company who can provide the labour and mixing service then. The drive is all coming up my side, so not bothered about damage. My neighbours is different of course.

    Maybe need to get a little dumper as well. Access is ok.

    thanks for all the info, as it helps me work out stuff.
    • CommentAuthortony
    • CommentTimeMay 3rd 2017
     
    Mixed with small. Electric mixer loads of times, it. Is easy, usually finished by lunch on the first day with three of us and all materials on site, I know several people who could do it on their own

    Don't be afraid of hard work, it is good for you and not all that hard either.
  3.  
    Posted By: marsadayI will look into a company who can provide the labour and mixing service then.

    I believe this approach is called 'batch concrete' or something very close to that?
    • CommentAuthormarsaday
    • CommentTimeMay 3rd 2017
     
    Well i am used to hard work, not done footings on this level before. Dug 4T of earth out of the ground and filled a skip with a barrow on my own in 2h's. Moved 10 T dropped off top soil in 3h's with 2 of us. Tough going with the shovel, but job done in the end.

    6T of ballast moved round the back the day before seems easy approach for me and mix on site. Just keep working all day long, should be ok.

    I think i need to speak to a mixer and see if he can get the machine on the drive with the hopper extended past my gate. If he can (and the neighbours agree) i think i will go for the easier option.

    Good to hear an alternative view tony. I will weight it all up i am sure over time. Looking to get started on this in june.
    • CommentAuthorgyrogear
    • CommentTimeMay 3rd 2017
     
    June ?

    You might fnd this useful...

    https://www.thebalance.com/pouring-concrete-in-hot-weather-845030

    gg
    • CommentAuthorcjard
    • CommentTimeMay 3rd 2017 edited
     
    Posted By: tony

    Don't be afraid of hard work, it is good for you and not all that hard either.


    Don't be afraid of smart work, it is better for you and not all that hard either
    • CommentAuthorcjard
    • CommentTimeMay 3rd 2017
     
    Posted By: nigelmCost was the same for standard delivery ready mix and they can make any mix you want, ours was C25 with reenforcing fibres added. Top job


    "Company A charges 80 quid a cube for delivery only. Company B charges 80 quid a cube for delivery and provides 3 lads to install it wherever you want"

    Seems legit
    • CommentAuthorgyrogear
    • CommentTimeMay 4th 2017
     
    on aggregate, they look like concrete proposals.

    gg
    •  
      CommentAuthorSteamyTea
    • CommentTimeMay 4th 2017
     
    :bigsmile:
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