Thread: Who knows about concrete?

Originally Posted by 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

I 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.

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

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

Hang the expense; I'd peg the join.

Bondall BondCrete - bonding and sealing agent

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?

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.

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.

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.

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