Tar/creosote/bitumen smelling reclaimed setts - Reclaimed granite setts

[settlayingbeginner]

Hi there, I’m just preparing to lay a large area of reclaimed granite setts, 10 sq mtrs to residential park cars on. I have two queries. Firstly I’ve noticed that the setts have a bitumen/tar/creosote like smell. I’ve asked a few people and I’ve been told that this is normal as many reclaimed setts come from under a tarmac surface and the smell is from the emulsion used to prep the surface when the tarmac was overlaid on the setts. I want to know if this is true, and if the smell will go, if there are any contamination issues from water running of such setts and also if it can be removed e.g. by shot blasting or other cleaning. Also they are non uniform in height and will be layed over a gritty sub soil that has recently been roughly levelled by jcb. Does this surface need to be whacked to compact it as much as possible before laying the fine hardcore bedding in layer and then mortar. Please advise on the tar like smell issue issue and your thoughts on laying surface prep. Thanks

[Pablo]

The smell will go don't worry about it as for run off it will only be slight diluted residue and not much of it. Did the JCB dig the area out to the level or fill the area up to the level. You mentioned fine stone you need to use type1 or mot or whatever it's called in England ( we call it blinding in Ireland). The stuff your talking about sounds like quarry dust which is rubbish for most things.

[settlayingbeginner]

Thanks pablo for re-assuring me about the smell. The jcb removed the 4-5" concrete slab that used to be there to get to the right level to have final surface correctly below the dpc of the adjacent house and then he simply scrapped the soil beneath flat again after disturbing it when breaking up and removing the slab. The fine hardcore we have is that mix of crushed tarmac and concrete you can get. We plan to use that and then sand and mortar to bed the setts in. What do you think? any better ideas appreciated.

[Pablo]

Just to clarify assuming you're using a 100mm thick sett. You need to be 150 mm below dpc with 100mm sett then at least 75mm of concrete/mortar bedding then a sub base of at least 100mm. This is at least 425 mm below dpc do you have that?. If so rake the sub soil/grade level and compact it and start from there it should be fine. Tarmac planings in a sub base generally aren't accetable but mixed with other better materials may be ok but don't hold me to that. Someone else may have a better idea if it's ok. For such a small area though the material cost of buying the correct sub base would be minimal.

[settlayingbeginner]

Thanks for your time and trouble responding with all the advice. it's really appreciated. We've got all our levels right for dpc's so we'll discuss alternatives/better sub layers tomorrow with the guys. Thanks for pointing us in the right direction. We're also going to be laying flags so may well be posting for more advice soon and when we get to those. P.S. total area to flag and sett with reclaimed stone materials about 100 sq meters hence cheaper sub material...Thanks again

[lutonlagerlout]

have you read the main site at all settlayingbeginner?
LLL ???