Sub base - Concrete for base

[Dan84]

Hi I was hoping you could help with a few issues I have with my block paving project first of all I need to know if it's ok to leave In concert that is protecting yeh main drain pipe can I compact mot on to it or build it up with more concrete and also if I need to compact my base to 100mm what depth will it need to start at?

[lutonlagerlout]

its all here
i would leave concrete round a drain pipe as long as its in the sub grade
as for the stone roughly 120mm to compact to 100mm
LLL

[Dan84]

Thanks for your answer just to clarify are you saying it is ok to compact hardcore on to the concrete as the sub base needs to be built up higher tan the concrete I was going to build more concrete upto the finished sub base Hight then compact the mot to level up to it will this affect final compaction as it suggests in your page on screeding? Thanks again for humouring my probably daft questions

[lutonlagerlout]

as long as you have at least 100mm cover over the pipe haunching it should be ok
tread carefully when compacting
LLL