On 2007-06-05 10:30:17 +0100, "Tim Downie"
said:

I'm widening my driveway and laying more block paving (standard 20 x10 cm
blocks).

Something that has always annoyed me about the old block paving is the
ability of weeds to set up home in all the gaps.

I know that the recommended way of "setting" the blocks in to use kiln dried
sand but is there any reason not to use a sand/cement mixture and deprive
weeds of a chance to get rooted in the gaps?

This would also mean I could pressure wash the drive without digging out all
the sand.

Any comments?

Tim

I think that if you read the oracles at pavingexpert.com, they will
tell you that if you are making a flexible drive (meaning MOT type 1
plus sand then blocks) that the gaps should be filled with sand only
and not with sand/cement.

There is a different procedure entirely for making a rigid drive.
This is where the base is something firm such as concrete. Then the
blocks are laid and pointed. As much as anything, this is to keep
water away from the concrete base. This is not a common technique at
all for domestic drives.

Having said all of that, I had a new drive laid just before Christmas
using handmade bricks. This has been done on a flexible basis and
has worked very well indeed. A few points on this -

- The jointing sand must be completely dry before use. If water
penetrates the bag, it's useless because you need the sand to trickle
finely into the gaps.

- Likewise the blocks themselves. They need to be dry, so a good 2-3
days without rain before jointing is good.

One issue that I have had is that there is a soldier course of bricks
(approx 250mm) immediately in front of the garage door. In front of
it, across the whole width, there is an Arco drain (strip drain) to
prevent water reaching the garage from the slope of the drive.
However, when it rains heavily against the door, wuit a bit of water
tends to flow from the door side towards the drain along the joins of
the soldier course, as a result tending to wash out the sand. In
order to address this, when I refilled the gaps I mixed in a little
cement with the jointing sand. This was poured very carefully into
the joints using a cakemaking icing bag so that none would appear on
the surface.
I then made a couple of very light passes with a plant sprayer. This
has worked well in that the material has not washed out. However,
doing this on the scale of an entire drive would be several days work
and not a good idea anyway.

As to the weeds.... I have found that a spraying of the whole drive
with Pathclear in mid March has worked well. It's supposed to last for
the season, but I don't mind doing it again if not.

I wouldn't want to pressure wash a drive anyway - destroys the character.