Binder course - Size of aggregate

[RobinParkes]

I've had a quote for my drive to be dug out and surface using bitmac. The spec was for 150mm hardcore, 50mm of 6mm binder and 20-30mm of 6 mm surface. Why would he want to use 6mm binder and not 20mm like most people seem to use? Would this make the job less durable? The guarantee is for 5 years. His price is £3500 for 160 square metres including 10 metres of edging bricks and re-setting 15 metres of existing kerb stones. This compares well with other quotes I've had and he's got a good portfolio of completed jobs.

[Big Phil]

probably the only reason he's quoting you 6mm asphalt for a binder course is that he will using the 1 load of material as 2 courses - which is cheaper for him but will make a right dogs dick of a job. For a driveway you need at least 50mm thick of a 20mm binder course. did his portfolio show pictures of completed jobs immediately after laying? i wonder if he's been back to photo them after 5 years.

[RobinParkes]

Thanks Phil, I suspected as much.

[Dave_L]

Aslong as the stone levels are accurate, 17 tons will cover the area at 50mm thick using 20mm binder and 11t will see the 6mm through.

I've not seen or used a 6mm binder course!

[JohnBoy59]

Steer well clear. You must have either 20 or 28mm stone in a binder course.