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Posted: Sun Dec 02, 2007 3:05 pm
by sting-a-ding
Just recently I saw some block pavers mixing cement in the sharp sand just before laying the blocks. Although they didn't seem to use too much cement I don't see the advantages.
How would this help or effect the laying process
Posted: Sun Dec 02, 2007 3:29 pm
by Pablo
Were they mixing the cement into the surface of the sand or were they making it up in a mixer and screeding it out. If they were just adding it to the top surface then it was probably some dodgy cowboy cutting corners.
Posted: Sun Dec 02, 2007 4:46 pm
by sting-a-ding
They were using a 360 excavator to mix it. But it didn't look like it was near strong enough for a screed mix plus no water was been added
Posted: Sun Dec 02, 2007 5:12 pm
by Dave_L
Ahha!!! Digger-mix! 
Posted: Sun Dec 02, 2007 8:12 pm
by seanandruby
dry sand and cement wont serve any purpose, it will have an adverse affect on the paving eventually. its neither rigid, or flexible. when ive had a lot of flags to lay ive knocked it up with the mini digger, as long as its well mixed it shouldnt be a problem. the trick is not to do too much as a semi dry mix will go off.
Posted: Tue Dec 04, 2007 8:38 am
by Tony McC
Cement will be detrimental to the laying course and to the medium-long term performance of the block paving. The whole point of flexible block paving is that is must be just that: flexible. By adding cement (or any other biding agent) to the laying course, these eejits have effectively sandwiched a rigid layer (the laying course) between two flexible layers (the sub-base and the pavers themselves). It doesn't take a materials scientist to figure out that such a construction is guaranteed to fail.
Adding cement is a tactic often used by incompetent buffoons who are incapable of preparing a screeded laying course. They are cowboys and should be treated with contempt, but I'm afraid this is what happens when people set up paving businesses with no effective training.