Posted: Fri Dec 10, 2004 9:27 pm
I have just had a 260m2 driveway laid with plaspave carrera blocks.
Within days around 25% of the blocks are showing movement (rock when stood on), and are throwing out the jointing sand. The driveway was laid 4 weeks ago, during which the temp dropped below freezing, with snow for several days. Also, I noticed that the contractor used jointing sand (kiln dried sand) which was damp, and the blocks were also damp when compacting after sweeping the sand. The contractor says that he is mystified by the rocking blocks, but that the jointing sand should not be the problem as it is purely decorative, and the blocks are stabilised after wacking by the base sand which creeps up the joint. I think this is rubbish and shows a basic misunderstanding of the inportance of dry sand filling the spaces to lock the blocks.
He has offered to redo the laying but I am concerned that the problem will recur if it is not properly jointed?
Is the damp sand, with many unfilled joints, the cause of the problem?
By the way, he has already had to redo the edges, which sank under my campervan, as he had no concrete base under the small edge blocks! Your site has been very helpful in enabling me to educate a 'professional'
Thanks
Ralph Sampson
Within days around 25% of the blocks are showing movement (rock when stood on), and are throwing out the jointing sand. The driveway was laid 4 weeks ago, during which the temp dropped below freezing, with snow for several days. Also, I noticed that the contractor used jointing sand (kiln dried sand) which was damp, and the blocks were also damp when compacting after sweeping the sand. The contractor says that he is mystified by the rocking blocks, but that the jointing sand should not be the problem as it is purely decorative, and the blocks are stabilised after wacking by the base sand which creeps up the joint. I think this is rubbish and shows a basic misunderstanding of the inportance of dry sand filling the spaces to lock the blocks.
He has offered to redo the laying but I am concerned that the problem will recur if it is not properly jointed?
Is the damp sand, with many unfilled joints, the cause of the problem?
By the way, he has already had to redo the edges, which sank under my campervan, as he had no concrete base under the small edge blocks! Your site has been very helpful in enabling me to educate a 'professional'
Thanks
Ralph Sampson