Who knows about concrete?

[Toxic_Avenger]

I've got a driveway at home with the 2 strips of concrete, and dirt in the middle. This makes it a little more awkward to put the landy on jack stands and maneuver the trolley jack underneath it.

Assuming I dig the gravel out in between, lay some sand or something down, then drill/peg in some reo into the existing slab, will quick set concrete be all right to use? Or is it best to mix my own?
Initial pour will be approx 3000mm x 500mm x approx 100mm

[rick130]

I've got a driveway at home with the 2 strips of concrete, and dirt in the middle. This makes it a little more awkward to put the landy on jack stands and maneuver the trolley jack underneath it.

Assuming I dig the gravel out in between, lay some sand or something down, then drill/peg in some reo into the existing slab, will quick set concrete be all right to use? Or is it best to mix my own?
Initial pour will be approx 3000mm x 500mm x approx 100mmI just used to use a painters plank for the trolley jack..... :)


I wouldn't use quick set Mitch, I'd mix my own.
Grab a mate or two, prepare properly and you'll knock it over quickly enough.

I laboured for a builder for a few weeks when I moved to Canberra and for a few days we were laying concrete paths, for the majority of the runs we used pre-mix, but one small extension we mixed our own and it wasn't too onerous.

[Redfoxie]

Do not use rapid set concrete!
by the time you mix and pour you'll have no time to level and smooth it off. It sets in 15 mins, like hard.
Since you are just infilling I wouldn't bother drilling into the existing strips, and if the slab isn't going to take a lot of heavy weight, rio is probably a waste. Add rio if you intend to drive heavy vehicles over it.

just dig out the middle to 100mm, make sure the base is compacted (if soft, compact it) then measure the area and order a small mixer load. Dig on Friday, pour on Saturday you'll be walking on it Saturday night, jack the Landy on it next weekend!

enjoy[smilebigeye]

Just re-read the size, you could mix that in a wheel barrow. Will take an hour, but save $$

[V8Ian]

Hang the expense; I'd peg the join.

Bondall BondCrete - bonding and sealing agent (http://www.bondall.com/concrete-additives/bondcrete/)

[Lemo]

It may be easier if you use bags of concrete mix (not the rapid set type) and add extra cement to get a better mix and finish. If you plan on jacking off it I'd be pegging and use gal studs to stop corrosion and concrete spalling/cracking in the old slab and some mesh wouldn't hurt?

[RANDLOVER]

For working out q'ty of concrete I found it is twice as dense as water, so if the vol. works out to 50L it'll need 100kg of concrete, which is what I discovered doing a footing wall for a water tank.

[trout1105]

You could simply just get a sheet of "form ply" and use this under the landy when you work on it.
It is incredibly strong and a plus is that you can drag it away and clean all the oil and gunk off it, Much easier than cleaning oil off concrete and cheaper and far easier than messing about with rio bar and cement mixers.

[Phil B]

As the others have said use bagged pre mixed non quick set concrete
The strength of the concrete is only as good as the sub grade under it so it will be advisable to compact the strip before you pour the concrete
It would also be advisable to lay builders plastic on the ground under the strip you are pouring after you have compacted it. This stops the sub grade sucking all the water out of your concrete before you have completed finishing it
Sounds like a lot of work for a small strip but it is all on the preparation.

[goingbush]

Rather than plastic sheeting I just spray the hell out of the area till its sopping wet. then pour Concrete.

[Gordie]

For that amount, I would get cement and builders mix(pre mix, or whatever they call it in your area...aggregate) and mix it in a wheelbarrow(if you don't have a mixer). Cheaper than buying premix bags, and you can add extra cement to the mix.

[fitzy]

My advise, depending on how long you want to stay where you are is always to do it really well, it’s a crap feeling when you cut corners on a job and it doesn’t stand the test of time then you have to demolish your work and do it all again hopefully you learn and do it properly this time.
Dig it out minimum 100mm, drill and pin into the existing concrete at 450mm centres half way through the profile to a depth of min 75mm with a 12 mm sds bit , hammer in some 12mm deformed bar cut to 200mm lengths tie to this some f72 fabric/mesh , order 1.6m3 of 25mpa, 12mm aggregate concrete from a concrete supplier at a slump of 80mm, find a Concretor or Concretor labourer to help you pour it, pay him $100 for a couple of hours work

[Vern]

I'd pull it up and poor a new slab instead of all the pinning and joins. But thats just me

[donh54]

From the days when I used to sweat for a living, I seem to recall that 1 cubic metre of concrete was around 25 builders wheelbarrow loads!
Makes a sheet of formply look real attractive

[Gordie]

Am I doing my sums wrong...I thought 3m x .5m x 100mm would be .15 of a cubic metre? Only a few wheelbarrow loads??

[Vern]

Am I doing my sums wrong...I thought 3m x .5m x 100mm would be .15 of a cubic metre? Only a few wheelbarrow loads??Yep

[fitzy]

Yep

Yes, the old 100mm trick appears again.
School boy error there[emoji849]
With that amount it would pay to use bag mix, although I would up the strength of it by putting in a bag of straight cement to every 4 bags of premix,

[RANDLOVER]

....... then you have to demolish your work and do it all again hopefully you learn and do it properly this time......


If a job's worth doing it's worth doing twice!?

[DiscoDiscoMan]

On the pre-mix bags I used recently they had an estimate of the volume per bag.
Check the bags at your local hardware store!

[Toxic_Avenger]

Cheers for the advice fellas- you blokes really do know your concrete!
This is probably something I'll try to knock out on a weekend- I have a moderately steep and narrow driveway, with about 1 car length's worth of flat which is my designated wrenching zone! So I really need to maximise this part first before doing the whole lot. A professional finish is not super critical, Pretty much if it's flat it will work.

[roverrescue]

One option that might work in Tamworth (worked for me years ago in cairns)
Is do all the prep work
Call a few local concrete batch companies - small guys more amiable than boral etc
Often on jobs they will have .2 of a cube left in the truck
For a carton they will happily drop it in your hole rather than in their yard to dispose of later

Of course you’ll need to be “oncall” but if you can swing that you might end up with
Easy cheap grey stuff???

Steve

[POD]

That last option is a great idea for such a small volume, but don't let them back up your driveway- if it's been done as a 2-strip arrangement it's been done on a tight budget and is unlikely to survive a truck. Buy or borrow a good wheelbarrow and make sure the tyre is well inflated before the truck arrives! Unfortunately most of us can't be at the beck and call of a concrete truck driver at short notice so I expect you'll be mixing it yourself. For small volumes like that, I buy sand, screenings and cement from a garden supply and mix it in a barrow, or mix it on a board. A board (about a meter square) is easier in many ways as long as your back is good for shoveling whilst bent over, you mix the ingredients dry first (use a D-handle square-mouth shovel) and then make a well in the centre, put water in the well and then keep turning the outside of the pile into the water. Add water a little at a time or you wash all the cement away. This is how concrete and mortar was always done prior to mechanical mixers. I wouldn't use premix bags for anything more than a letterbox post. And with such a small area, the cost of going a little extra depth, say 5", would be insignificant. Personally I wouldn't pin it to the existing although it can't hurt, I'd go 5" thick with a strip of reo down the middle, pour a little concrete over the reo then use a steel hook to lift it just clear of the ground before pouring the rest.

[austastar]

Hi,
Premix is about $40 per m^3 from our local landscape place and 2kg bags of cement are about $18 if I remember correctly. About 12 bags for 1m^3 of premix.
Mix it 5 to 1 and not too sloppy.
Cheers