Forum: Block Paving
Topic: Concrete for edging.
started by: Hawaii04

Posted by Hawaii04 on 23 April 2017,21:44
Hi. About to start the edging on my block driveway soon and got a question on the concrete mix. I recently had a bulk bag of ballast delivered and it was made up of 20 mm gravel. Is this stuff ok to bed the edge blocks on or would I need 10 mm. when I made a batch of concrete up, it looked nothing like the stuff Tony uses on his edge restraint video. I reckon 10 mm gravel would be easier to work with but I'm no pro. Any advice appreciated.
Posted by Tony McC on 25 April 2017,17:10
The "stuff" I use on the video, and what is popular throughout the north, is a mix of very coarse grit sand with cement. Some southern-types give me grief by claiming it's not a concrete but a mortar. Does it matter? It works; it works well; and it means I don't have to buy another type of coarse agg.

For a definitive concrete, you should use an agg of 6mm or above, and you're right in in surmising that a 10mm agg would make an easier-to-work concrete than a 20mm agg, but....when needs must, even a 20mm agg would be OK.

Posted by lutonlagerlout on 25 April 2017,19:48
we use a yellow ballast with 20mm aggregate  down these parts ,probably the same in kent
the key issue is to make sure you have sufficient depth of concrete under the edge,for me this means minimum 150mm and a stronger wetter haunch angled at 45 deg from 20mm down from the top of the paving
never seen red sand down here

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