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Posted: Mon Nov 20, 2006 4:47 pm
by faheem
Hello All,
Advice on the following would be much appreciated. I had my drive tarmaced in the summer. During the hot weather I noticed scuff marks due to wheel turnings. I approached the contractor and he said you cannot avoid these.
On looking through some photographs I found a photo of the drive when the sub base had been laid. The next photo I have is when the driveway was completed. As far as I can recall the final layer was laid in one day. So I am suspecting the base layer was not laid and all I got was a 50mm wearing layer on top of the sub base.
So my questions are: is it possible to lay a base layer and a wearing course in one day (on a hot day) and what impact would there be if the base layer had not been laid and all I got was a sub base and wearing layer.
Posted: Mon Nov 20, 2006 5:38 pm
by MatthewWakeman
thats the ideal way of working it makes for a very tight bond between the base and the wearing course. scuff marks are not that uncommon in hot weather especially on newly laid bit mac
regards
matthew
drivewaycompany.co.uk
Posted: Mon Nov 20, 2006 6:53 pm
by Dave_L
Can confirm that is the best way to do the job.
What was the spec of the surface course? Did you get a full spec?
These power steering marks/scuffs can be a big problem, but we always inform our customers of this potential problem.
After a couple of years or so after laying, the surface course seems much more resistant to tyre scuffing.
Posted: Mon Nov 20, 2006 6:54 pm
by Dave_L
To answer Q2 - this would be a most unacceptable situation - is the driveway still nice and level with no dips/puddles etc?
Posted: Mon Nov 20, 2006 8:37 pm
by TarmacLady
Scuffing occurs in hot weather because the tarmac goes soft at about 130F/50C -- easily reachable on a hot day, as the black surface absorbs heat like a sponge. Power steering exacerbates the problem.
It gets less and less as the surface ages (over a few seasons) because the volatile oils evaporate out of the mixture, leaving the harder solids (that have a higher melt point)...but this will change over time, as well, as a drive that has not been re-sealed (with an *bitumen* based sealer -- either solvent-based or emulsion will work, and not a latex emulsion!) will evenutally begin to break down, as there's not enough to bind the pebbly bits together anymore.
Posted: Tue Nov 21, 2006 6:44 pm
by Dave_L
There is a big bearing on the spec of the material versus it's resistance to scuffing - the latest SMA bitmacs are far superior in this respect.
It's what we specify on 90% of our residential driveway work.
It also depends which quarry it comes from and at what time of day, but that's a story for another day! 
Posted: Wed Nov 29, 2006 5:30 pm
by faheem
The driveway is level, with two minor dips (just where the car front wheels stop). The contractor did say that overtime it will harden. However, I am still unclear on whether I should have got a subbase+base+wearing layers, beacuse the information on this site suggest tarmac should be laid in three layers and I am suspecting that only two layers have been laid.
Posted: Wed Nov 29, 2006 5:55 pm
by Stuarty
the sub base will be MOT, not tarmac. A domestic drive should be subbase + base course + wearing course. So the subbase would be MOT, then a base course and finally a wearing course.
Posted: Wed Nov 29, 2006 10:30 pm
by Dave_L
Full road construction [tarmac] is laid in three layers, being road base, base, then surface.
Yoru driveway, as Stu has said is compacted stone, 20mm base and your choice of surface course.
Not sure I'd be happy leaving my customer with 'minor dips' where their car wheels rest! That suggests poor sub base preparation......