Concrete garage base

[James]

I want to lay a garage base at the bottom of my garden, for my motorbikes. It is 25 metres from the road side so delivery of pre-mixed concrete will be a problem, or expensive, or both.

I can mix the concrete myself using a cheap to hire mixer but I need some advice on the amount to lay in one batch, to avoid cracks.

The slab will be 6m x 4m x .125m = 3 cubic metres.

The mixer spec says it can mix 85 litres in 6 minutes.

Assuming I'm just tipping the concrete straight into the ready prepared area, with a bit of tamping and smoothing, I can probably mix and tip about

12 loads = 1 cubic metre, in 70 minutes, with possibly 20 mins more for actually shovelling all the ingredients into the mixer.

This means I can lay one third of the base in about 1.5 hours.

So, help needed here :- What is the best way to do this?

I'm assuming I can't just lay the whole base over a space of 1.5x3 hours =

4.5 hours as the concrete at one end will have started to go off before I've finished at the other end?

Should I lay 2 slabs, 2 metres wide each, with a 2 metre gap between them? Then, I could wait a few days until they have both gone off then fill in the gap with another slab? Will this be prone to cracks between the 3 separate sections?

Any ideas anyone. All comments and advice greatfully received.....

Cheers James

[Bob Morrison]

Rent a line pump and do the job in one day.

Yes, it will be more expensive, but you will get a better result and you will save your back since you won't have to haul 3 cubic meters of sand, gravel and cement by hand.

[James]

I don't mind doing the hard work as I'm trying to get fitter anyway! I'll move the stuff to the site at a leisurely pace over the preceeding days.

I got a quote for ready mix to be pumped into position and it was twice the cost of me doing it myself.

[Kickstart]

penny wise ? Mixing consistent concrete and placement is critical to a successful job. Pound foolish ? Just don't hurt yourself or your Mate, he may not want to be as fit as you towards the end of the day

kickstart

[shazzbat]

You're not going to get fit, you're just going to get knackered. I would split it lengthwise, ie do one lot of 2m x 4m, then do the other lot when it's set/when your back isn't hurting so much.

And don't forget your estimates of time to do the job are going to be way out because of all the messing about with shuttering, haven't got enough nails, now the hosepipe's leaking, can't find a washer for it, now the wife's saying the video won't record, your neighbour comes round to borrow something you can't find, the cat has been sick, etc etc, the list is endless.

Steve

[James]

This is what my question really comes down to - will it crack if I do it in strips? Do I have to wait for the strips to completely go off before putting another one next to it?

lol. I'll build in contingency time then!

[Italian]

Listen up everyone that is thinking of mixing there own concrete for a situation such as this. Or anythng over 1 yard

======IT WILL NEVER PAY TO DO IT YOURSELF. HIRE A TRUCK AND OR A PUMP.======

You for got things like roding the concrete to make sure it is at the right level and if it is not having to go back and move material from another area or rake it up closer. You forgot bullfloating it to get the rocks down after its is roded you for got running the edger along the forms for the first pass....plus much much more this all takes time and must be done at a certian "set" time in the the process. Mixing and pouring and mixing and pouring will greatly interupt this process...can it be done yea sure but how much do you want to do it again when it fails in a year or so? Look if you want to do it this way do very small sections at a time and place rebar dowels at the edge of the slab ready for the next pour. You can drill holes in the form and place the rebar in these holes the next day take these forms out and pour up to it and repeat. BTW you dont necessarialy have to do one pour a day you can do as many as you can just make sure to finish the process with the previous one first then move on to the next one. Butting slabs together is not the problem its not tending to the already poured concrete that is the problem......

if you figure just the materials you are already so close to the cost of redimix it is not worth the hassel...time is also money......

James wrote:

[James]

Can you explain what running the edger along the forms for the first pass is? Creating a smooth edge around the slab or do I have to separate the slab from the form?

Fair point. I will do smaller slabs and ensure I have lots of mates around to help.

Can I start the next slab while the one I'm butting up to is still damp without risking cracks? Or do I have to let each one go off before I start the next?

Mixing myself the cost will be about £300. Having readymix delivered to the roadside will cost £370 but that does not include the time the truck has to wait while the mix is wheelbarrowed 25 metres down the side of the house and through the garden to the work site. 3 cubic metres is about 90 barrows full so that will take a couple of hours, even with plenty of help.

Waiting time for the truck is £70 per hour adding another £140 minimum, which is almost doubling the cost and is a hell of a lot of heavy shifting to move 90 barrows full, all against the clock as the concrete is going off during those 2 hours whilst being moved.

I have a quote of over £730 to have it pumped to that is still too expensive given I can mix it myself for less than half the price.

Conclusion : If I mix it myself in small enough batches I can ensure a good quality mix each time and do the whole project for significantly less money than approaching it any other way.

[JerryD(upstateNY)]

James wrote: Conclusion : If I mix it myself in small enough batches I can ensure a good quality mix each time and do the whole project for significantly less money than approaching it any other way.

Good luck !! Try finding a friend who knows something about pouring concrete. Trying to pour a garage slab when you haven't any idea of what you are doing, is a recipe for disaster.

[James]

Thanks for the warning! I'm trying to avoid disaster by doing my homework and asking the right questions in the right places :-)

[James]

lol obviously want to give it a go. Perhaps that's true, I'd just not realised it!

Yes, I think it would be best rather than a race against the clock to move all the premix from the roadside.

Great minds must think alike. I've got drainage, hot and cold water, TV, cat5 and phone wires already down!

Thanks for all your advice, Sue. This just leads me now into the murky world of what's the best mix to use? The builder's merchant supplies aggregate which is fine sand mixed with fine gravel. I want something really strong and don't mind paying for extra cement to achieve it so do you think a 4:1 mix is suitable? Bearing in mind I'm going to build a big heavy log cabin on top, quite possibly with a hot tub inside it, not to mention some motor bikes and machinery.

[shazzbat]

I've heard all I need to hear now. Will you marry me?

Steve

[Palindr☻me]

LOL, there must be less drastic ways for you to get your hands on an auto-feed bed and a suds pump...

[James]

I'm building the cabin myself so have no spec to work to.

Well you live and learn. I thought the strength all came from the cement!

I take it that is 1 cement, 2 sand, 4 gravel?

I'll have to ask the builders merchant which ratio of sand to gravel the aggregate comes in, but one would think it is a standard mix if that's all they supply to the trade.

Thanks for the string loop technique, I was wondering how it was done without the mesh just sitting on the bottom or it standing on blocks.

lmao. I'm kind of wanting the same strength, for overkill as you nicely put it, but was hoping 125mm with one cross mesh would do the trick?

[Palindr☻me]

OK, so find a log cabin manufacturer that makes one similar to what you have in mind and get the spec for the base for that..

It's one of those things where a mix is stronger than any of the components, individually.

Yep

There's all sorts of stuff called various things from 40 to dust, to all-in-one ballast, to heaven knows what. I like to mix my own..that's the way my dad taught me..

lol..it's the way my dad taught me..

How long is a piece of string? I used the same spec that the workshop where I worked had been built to. The extra cost was not a lot and it isn't going to break, no matter what I do to it.