Laying concrete yard

[carlsbergy]

I have just laid new drainage out the back of my house and have broken up the old concrete, to access. I now have an area of approx 12ft x 6ft that needs re-concreting after I cover up the new drainage. Should I use crushed hardcore and then a plastic membrane on top, and then lay the concrete? What mix would I use of cement to ballast? I also have another area that needs raising by approx 6 inches,(15ft x 6ft), it already is concrete, do I need to PVA and then pour concrete straight on?

Thanks

 

[noseall]

Use stone i.e. mot if the ground is soft or clay like.

No need for membrane.

Mix it at six parts ballast to one cement.

Concrete on top of concrete is no prob so long as the existing slab is not covered in grease/oil, moss or any other crud. Wetting it first will encourage the two to bond but will not guarantee against lift or separation.

Should any moisture find its way betwixt the two slabs and subsequently freeze then it will lift. It would need to be bloomin cold though.

 

[carlsbergy]

Thanks noseall, one more question how do I work out how much ballast to order? Thanks

 

[noseall]

Thanks noseall, one more question how do I work out how much ballast to order? Thanks

You will need 3 tonnes of ballast and 20 x 25kg bags of cement.