Question How to lay a simple slab of concrete

Discussion in 'Building DIY, Machinery & Tools' started by Mark, Aug 5, 2013.

  1. armysnail

    armysnail Active Member Premium Member

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    You tube has a million videos on laying concrete slabs. The main thing is to decide how much weight it will take. If a vehicle will drive on it you need steel reinforcement. If not, aim for at least 100 mm for light foot traffic. You can buy the gravel / sand mix bulk and add concrete as you go. Mixers are defineately the go. You get what you pay for so try Tradetools at Caboolture. All their tools are heaps cheaper than Bunnings/Masters and that is for the same brand. Make sure you use a bucket to measure. Shovels are not accurate. Don't add too much water. The more water the weaker mix. Put builders plastic down and then either cover when laid or wet regularly with a hose. Concrete sets by a chemical reaction, not drying out.
     
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  2. Mark

    Mark Founder Staff Member

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    I popped into a concrete supplier on Friday to get an estimate on materials but surprisingly the lady at the front counter wasn't much help.

    She pulled out a chart thingy but couldn't understand the workings... She ended up guessing it would take about 70 bags to do 3 x 2.5 m bbq area but I don't think that's right especially if I add gravel and sand.
     
  3. armysnail

    armysnail Active Member Premium Member

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    She might have given the number of bags of concrete, not cement. It may be worth looking at mini tankers to supply pre mixed concrete. You can finish the job quickly with a more consistent product and be guarenteed your minimum hardness.
     
  4. Mark

    Mark Founder Staff Member

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    Hmmm, ready mixed might be the cheaper option in the end - good call. I'll just do all the form work and then get the mix I guess that has to save some money surely. I'll investigate the costs of getting a mini mixer in...
     
  5. Justin Dallas

    Justin Dallas Member Premium Member

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    We did a 12m x 6m slab, & a 4m x 4m slab - by hand, in a single day. Industrial thickness (150-200mm thick)
    took 6 of us the whole day but, definatly doable by hand. Here in South Africa labour is real cheap & local Zulus are strong.
    I think the labour cost like R1000 ($100)
     
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  6. Mark

    Mark Founder Staff Member

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    That's a great effort! Do you think a smaller slab or say a pathway could be done by one person? Or, would it be a touch too ambitious?
     
  7. Justin Dallas

    Justin Dallas Member Premium Member

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    Mark - Id say its doable, but back breaking work for one person - also, you only have a good couple hours to mix, pour & trowel. if you want longer working/setting time, start that evening when the heat of the day is gone, & its cooler - work through the night & finish the next morning/day.

    For a small job of say 3 x 3m, definatly 2-3 people at least. But, hiring a small electric mixer is also an option (I think you were wanting to buy one a while back)
     
  8. Justin Dallas

    Justin Dallas Member Premium Member

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    One thing I found is that if you power float floors/slab (which is like a floor polisher with steel blades) you significatly increase surface hardness (think industrial flooring). There are also some amazing additives and polymers you can float into the wet cement to color and texture the slab - making for a finished floor that doesnt need tileing or carpeting.
     
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