Cold lay tarmac

[stevemff]

Hey All,

As I mentioned in another tread I've just dug up part of my tarmac driveway to run a new mains and had a question about the cold lay tarmacs you can buy.

The trench I've dug is about 30cm wide and about 70cm deep. When I cut the old drive out it was a thin tarmac surface on top of rocks (hardcore?) before to got to the soil. I'm not sure what exactly the hardcore layer consisted of but it was a bugger to get through with the angle grinder and the breaker on the sds drill.

My question is once I've back filled all the soil into the trench and tamped it down do I need to put another hardcore layer down before I add the cold lay tarmac a you can buy? Someone told me you can just put it on top of the soil but I'm dubious about this and would worry about it sinking over time with the car traffic over it.

So do I need a hardcore level and I'd so how do you mix this up? Stones and concrete mix, just concrete etc?

Cheers
Steve

 

[Newboy]

compact the trench as much as you can - try hiring a trench wacker (depending on what you've put in the trench and how protected it is!) then backfill with MOT and top with tarmac. Backfilling with soil and tarmac will almost certainly sink

 

[stevemff]

Thanks nb, was a lot easier to work with than I thought. Still seems a little soft after 24hrs but I'll leave it another 48hrs before putting any load over it.

 

[noseall]

Cold applied tarmac has a different cure rate to that of regular Mac and relies upon the solvents evaporating rather than just cooling and setting etc.

 

[stevemff]

Good to know, the pack said 35hrs but I guess that would be very dependent on environmental conditions so I'll take care.