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.
Thanks. I've just been looking at that link but it makes no mention of sand/cement mixtures which, on reflection, don't really fit with the concept of "flexibility" which is kind of inherent in any domestic blockpaving that
*isn't* laid on a solid base. Maybe I'll have to think again.
Would a gallon of brick acid sloshed about deal with that?
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.
Does anyone make a fine-powdered persistent weedkiller that you could "dilute" with kiln-dried sand and brush in to the gaps? That would be much more useful than sprays like Pathclear; most of that gets wasted on the blocks.
Sand only, sand/cement *WILL* stain concrete blocks Brick acid will clean the cement stains off, but will also etch the surface of the blocks and expose the aggregate - highly variable results, and it will affect the colour.
Use weedkiller annually, or a stiff broom to remove the weeds & crud. They only grow in the surface of the joints, as the blocks shoudl be too tightly fitted to allow weed growth from below.
There are 2 types of adhesive sand for this. One sticks to itself only, and the much more expensive type also sticks to the blocks, and lasts much better.
Based on my experience today, I'd say - Get a man in!
Getting everything levelled & smoothed off is *much* harder than I thought it was going to be. Cutting blocks is a pain.
Part of the problem is that I'm adding to an existing driveway and the drive has both positive and negative curves (i.e. humps and hollows). In an ideal world I would rip the whole lot up and re-lay it all flat but that's more work than I'm prepared to do.
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