The Brew Cabin

I have a contractor currently working on removing my tarmac drive to replace it with block paving. He is going to keep the existing sub base as it seems very sound. He is also extending the driveway replacing a lawn where he has dug down about 250 mm. He is planning to use some of the old broken up tarmac as a deep base mixed with some rubble and then a layer of scalping then obviously the sand. He seems to be a reputable paving contractor and I have seen some of his finished jobs which look A1, but I am wondering about using the compacted tarmac, I would have thought that it would need to be broken up very small to be any good. Would apreciate your comments.
Dave - Surrey.

The question is "How is he removing the tarmac drive?"

He has managed to lift the tarmac so the base looks ok. My main concern is that he is going to use the tarmac (
he has now broken up ) for the part of the subbase for the extension to the existng drive which was a lawn over chalk.

Thanks

Broken up bitmac is not a suitable sub-base material. As an oil-based product it degrades over time and can cause settlement.

The only acceptable use for the old bitmac would be as a thin blinding layer over the excavated sub-grade, and for such use, it should be broken up as fine as possible, spread out in a layer not exceeding 50mm thickness and compacted before placing of a proper sub-base, which would need to be at least 100mm thick, and not just a token 'layer'.

Skimping on sub-bases is the single biggest reason for rutting and settlement of block paved driveways. The best advice I can offer is that you should ensure a sound sub-base of at least 100mm of approved sub-base material (DTp1 or similar) is used.