Edging blocks and installation - Concrete or cement

[energyfish]

Hi All,

Just had a quote for block paving for my drive. I have specified that the edging block should be Marshalls ks bullnose and haunched onto concrete. The contractor has come back and stated that they can't be haunched onto concrete as the block wont stick. This sounds a bit of a cop out but I may be wrong. Would appreciate some advice.

Many thanks

Al

[Rich H]

Eh? What do they suggest using then, toffee?

[energyfish]

They suggested just plain cement and sand mix (apols forgot to mention that) as the blocks wont stick to concrete (?), but I belivee that this wont be strong enough and will basically break away in chunks. Is this BS or not ?

Any advice appreciated

Many thanks

Alan

[Rich H]

Ahhhh. In short, mortar = sand + cement + water, concrete = sand + aggregate + cement + water. (Tony has a large section on these topics on the main website).

If your edges are to retain the drive, they should be laid on concrete. Most contractors use all-in ballast (or just 'ballast') & cement to do this. It is a slower process to lay blocks on lumpy, crunchy ballast mix than it is to lay on nice fluffy sharp sand mix.

If the edges don't restrain the drive (e.g. if they against a wall or existing edge or kerb), then a sharp sand and cement mix is fine.

To talk about 'stickiness' is a red herring. If blocks and kerbs don't stick to concrete, we'd better start ripping up every highway, path and drive in the country.

[energyfish]

Many thanks Rich,

Just wanted to be sure that I want being fobbed off with a lame excuse. The paver was suggesting that only the entrance to the driveway needed concrete but as there are soft planting borders all around the the drive, it seemed a bit dodgy to use purely a sand/cement mix.

[Rich H]

It is, really. Because they are free edges, they need to be strong, particularly if they may be trafficked. If there's no possibility of a tyre going anywhere near them, a sharp sand mix should be adequate (I'd still rather use ballast, though!) A sharp sand & cement mix is still strong and will set hard, but compared with concrete it is more brittle. Fine for a patio but not a free edge that has to withstand the forces to be expected from vehicular traffic.

[Dave_L]

Hi All,

Just had a quote for block paving for my drive. I have specified that the edging block should be Marshalls ks bullnose and haunched onto concrete. The contractor has come back and stated that they can't be haunched onto concrete as the block wont stick. This sounds a bit of a cop out but I may be wrong. Would appreciate some advice.

Many thanks

Al

We've laid loads of these, onto a concrete bed - with no problems whatsoever.