[mav]

Just finished a job ( a patio ) and it was made of clay block paving, light creamy colour and I thought it was really hard work to get clean and the gaps were quite big between the block, it took three bags of sand to refill  didn't quote a lot as it was a small area and they were elderly couple but there were lots of items needed moving around so I didn't make much if any profit on this one ...Live and learn ... as they say lol
On the bright side though they said they were happy and would probably call with more jobs, and they would recommend me. 

so a result I would say

[drive surgeon]

clay is prob worst type of block paving!

[dandandan]

Did you keybond the joints mate so sand stayed in?I cleaned and sanded some block last week and it had sank in places,i had to sand some one inch gaps  were car had been running,told custy to get onto bloke who laid it but i would do my best.dan

[drive surgeon]

when the joints are that wide they need to be cemented or keybonded or the sand will just wash out and they will sink or move. which will ruin the drive,

[drive surgeon]

hey dan have you tried majic sand?