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Posted: Tue Feb 19, 2008 11:30 am
by taskew
Recently laid flexible brick paving is showing sign of movement after vehicle traffic. Joints are opening, individual pavers are becoming loose and sand is dissappearing into the joints. Sub-base is hard tarmac/concrete with a 40mm sand bedding course. Paving is fully restrained at edges. After laying, the paving area is sanded and compacted three times and initially appears firm and well jointed. Jointing sand is kiln-dried to BS 7533. - which is quite fine. The bricks are an irregular "Dutch" type -laid on edge and the manufacturer recommends a coarser grain of sand of 0-4mm. Could this indicate the cause of the problem?
Posted: Tue Feb 19, 2008 7:08 pm
by Pablo
What kind of sand was used as the bedding course and was it raining when the bed was screeded.It's possible that the compacting plate wasn't up to the job also. Is the course sand recommended for jointing or bedding.
Posted: Tue Feb 19, 2008 10:34 pm
by matt h
seems to be a compaction problem,re sand and use rubber mat with compactor again... what weight vehicle traffic?
Posted: Wed Mar 05, 2008 6:06 pm
by Tony McC
I'm not sure if the OP has disappeared back into the ether, as I would have expected a reply to the comments put forward by Pablo and Matt, but for future reference, there is a real risk of block movement when a rigid or semi-rigid base is used, especially if there is no provision to drain the laying course material. The reasoning behind this is given on this page
Posted: Fri Mar 07, 2008 2:21 pm
by MRA
Tony McC wrote:I'm not sure if the OP has disappeared back into the ether, as I would have expected a reply to the comments put forward by Pablo and Matt, but for future reference, there is a real risk of block movement when a rigid or semi-rigid base is used, especially if there is no provision to drain the laying course material. The reasoning behind this is given on this page
Agreed. Also, any future maintance or repair to services could be a nightmare if you need to excavate through a solid base to access pipes or cables.
Posted: Fri Mar 07, 2008 4:34 pm
by taskew
Sorry for the delay in responding guys - but the paving manufacturer had been to site and promised a report that has now arrived. This tends to agree with most of your comments and the finger of suspicion points to saturation of the bedding course. Its significant that the areas in question were laid the first two weeks in January (very wet if you remember). Subsequent areas laid in dry weather appear to be quite stable. Its a large project and I'll post any further developments in due course.