Posted By Descarte Dont know if it is any less confusing but: 'bitumen' refers to heavy, black viscous material obtained from the distillation of crude oil. The word 'asphalt' in British English refers to a mixture of mineral aggregate and bitumen (tarmac in common parlance). The word 'tar' refers to a black viscous material obtained from the destructive distillation of coal and is a chemically distinct material different to bitumen.

Posted By peter gotch 1 Hi Kevin, None of it good for you, though some repairs can be cold applied. Recycled materials [i.e road plane and mix with new materials] may be more carcinogenic. Quite a lot of traditional tar tarmac in some Counties in England. You might find some information on the County Surveyors website. Good luck. Regards, Peter

Posted By David Bramall Kevin I will attempt to clear up a few of your points. 1. There are two main "binder" constituents of macadam materials. 2. Bitumen is a by product of oil distillation and is used as a binder for many types of macadam. 3. Tar is a product of coal and is carcinogenic - it is now no longer used by highway authorities in the UK because of this. 4. Bitumen Macadam and Tar Macadam are essentially the same products but use different binders as above Bitmac uses bitumen, Tarmac uses Tar. These products derive their strength from the coarse aggregate which ranges from approx 2.5mm up to 40mm depending on the mix required. The binder is used purely to bind the aggregate together into a stiff matrix. 5. Asphalt is nowadays a similar mixture to macadam the difference being that it uses a large proportion of fine aggregate - sand and lime filler to provide the strength and usually a greater proportion of binder. This is based on trying to produce a man made version of Trinidad Lake Asphalt which is a naturally occurring substance containing various binders, aggregates and fillers. 6. There are many new variations on both macadams and asphalt mixtures but they are roughly based on the above mixtures - only using polymers etc to modify the binders, use of different types of aggregates etc. Hope this is helpful. DrB

Posted By David Bramall Kevin Ref my previous response - tar as a binder is indeed very very harmful, bitumen does give off fume but in well ventilated surroundings it is considered harmless. Obviously, we should not stand over a load of the stuff and inhale deeply, it is an irritant, but no evidence as yet that it is actually harmful, toxic etc. Thanks for not realising that I am an expert in the field of macadams - don't worry, the advice is free whether you appreciate it or not. Keep er lit DrB

Posted By KevinD Dear All, Many thanks again for the references and advice. DrB, apologies if my post sounded as if it questionned your expertise, this wasn't my intention at all as your clarification has helped greatly. I was trying to bow to those on the forum (yourself inlcluded) with greater knowledge on this subject to understand the type of fumes etc people are being exposed to when road surfaces are re-heated and what PPE might generally be required (if any). I think the difficulty with this area is that different surfaces have been put down over a number of years (i.e. tar, asphalt, bitumen based) along with any diesel, oil etc spills and it is difficult to know what people might be exposed to. Regards, Kevin