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Fitting rockfaced gravel board as lawn edging.

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  • NollieNollie Girona, Catalunya, Northen SpainPosts: 3,379
    Ah, I see your confusion, yes I would put concrete in the base. OK, time for The Extra Detailed Nollie the Bodger Plan! This is what I would do:

    1. Dig down 5-6inches, level and tamp down the base so its flat and even, place the gravel board in temporarily to check its level. At this point it will be an inch or two than you want. Take the board out again. Do this the entire length, so you have a good level trench bottom all the way. You can do all this prep in advance before you mix the concrete, the day before, say. It will give you a sense of achievement and make the next step easier...

    2. Now, courage! Mix your concrete with water to the right trowelling consistency in a wheelbarrow - it will seem too dry and first but persevere. Do not do your mixing in the trench you wont get it mixed properly and do not add water to the trench, you will weaken the concrete!

    Its a personal choice re quick set or not, my preference in not because it gives you more time to work. You could buy bags of readymix concrete (just add the exact stated quantity of water as per the instructions on the bag) rather than guess the ratios of sand, cement and water. This is more expensive tho, probably at least a bag per board.

     3. Trowel your concrete mixture into the trench, to about an inch or two in depth, then place the gravel board on top, shuggle to get good contact, place you spirit level on top and tap down gently with a rubber mallet to level. Be generous with the concrete and it will ooze out the side a bit, reinforce with more generous dollops of concrete at the front edges and joints, smoothing and pushing these blobs with your trowel to get a good contact with the board. You wont have to hold it in place for long, less than a minute, probably.

    4. Make up next bag/batch of concrete. Repeat as above, leaving a mortar gap between the first and second board. You can either fill the mortar gaps as you go or leave them till the end.

    By doing it one board at a time, you can take your time. It will be a bit of trial and error to start with. It will be messy. Blobs of concrete will end up in strange places. This is normal.

    5. Once all set in and mortared, let it dry for a few days at least, before filling the remainder of the trench with earth, gravel, etc., and tread down well so all are firmly anchored in the ground. If you prefer, you could mix a weaker, pouring consistency concrete and use this to backfill, but earth will do the same job cheaper.

    6. Stand back and admire your handiwork  B)
  • WillDBWillDB Posts: 2,473
    edited April 2019
    Re mixing concrete, you can get a mixing tub like this and just use a spade to mix the cement and sand. Add your water bit by bit, you want the concrete to be stiff enough to hold it's shape well. If you make it too wet and sloppy add more cement.
    Image result for large plastic concrete mixing tub
    (I use my tub for leaving my plants standing in water if I go away for a week in the summer!)
  • Nollie said:
    Ah, I see your confusion, yes I would put concrete in the base. OK, time for The Extra Detailed Nollie the Bodger Plan! This is what I would do:

    1. Dig down 5-6inches, level and tamp down the base so its flat and even, place the gravel board in temporarily to check its level. At this point it will be an inch or two than you want. Take the board out again. Do this the entire length, so you have a good level trench bottom all the way. You can do all this prep in advance before you mix the concrete, the day before, say. It will give you a sense of achievement and make the next step easier...

    2. Now, courage! Mix your concrete with water to the right trowelling consistency in a wheelbarrow - it will seem too dry and first but persevere. Do not do your mixing in the trench you wont get it mixed properly and do not add water to the trench, you will weaken the concrete!

    Its a personal choice re quick set or not, my preference in not because it gives you more time to work. You could buy bags of readymix concrete (just add the exact stated quantity of water as per the instructions on the bag) rather than guess the ratios of sand, cement and water. This is more expensive tho, probably at least a bag per board.

     3. Trowel your concrete mixture into the trench, to about an inch or two in depth, then place the gravel board on top, shuggle to get good contact, place you spirit level on top and tap down gently with a rubber mallet to level. Be generous with the concrete and it will ooze out the side a bit, reinforce with more generous dollops of concrete at the front edges and joints, smoothing and pushing these blobs with your trowel to get a good contact with the board. You wont have to hold it in place for long, less than a minute, probably.

    4. Make up next bag/batch of concrete. Repeat as above, leaving a mortar gap between the first and second board. You can either fill the mortar gaps as you go or leave them till the end.

    By doing it one board at a time, you can take your time. It will be a bit of trial and error to start with. It will be messy. Blobs of concrete will end up in strange places. This is normal.

    5. Once all set in and mortared, let it dry for a few days at least, before filling the remainder of the trench with earth, gravel, etc., and tread down well so all are firmly anchored in the ground. If you prefer, you could mix a weaker, pouring consistency concrete and use this to backfill, but earth will do the same job cheaper.

    6. Stand back and admire your handiwork  B)
    Thanks Nollie for such a detailed response. It covers so many doubts I had in my head!

    I will probably do the digging part today to make a level trench. I am thinking to get the quick setting concrete mix as it seems easier. Do you think something like ''Blue Circle Ready To Use Postcrete - 20kg' from WICKES' would be appropriate? With the quick set cement, should I still add water in a wheelbarrow and then pour it in the trench? Or because it is quicksetting, I won't have much time to mix separate and then pour?
  • NollieNollie Girona, Catalunya, Northen SpainPosts: 3,379
    I dont know that particular product, but all ready-mix will have full instructions on the packet. Its mixed and used the same, see 2 and 3. If still in doubt, time to watch a few utube vids of how to mix concrete! Alternatively, get a brickie in  ;)
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