Sandy/soft soil near sea - Subgrade preparation problem

[james-78]

I'm starting a DIY project laying cobbles/cubes in front garden. area is approx 25m2.

My plan was to have:
1 - subgrade
2 - geotextile fabric
3 - 75mm hardcore subbase
4 - 50mm fine concrete bedding layer
5- cobbles/cubes with 1:50 gradient.

My garden is close to the sea and I have sandy soil. I have started digging out garden to appropriate levels and the digging has been easier than expected - this is where my concern starts. I have dug deeper and can't find what would probably be called "good proper subgrade material" but just sandy soil thats easy digging manually - no mini digger.

Would it be ok to whacker plate the sandy soil down in an attempt to get compaction to refusal? which i'm not sure I will get and than carry on with project as planned or should the plan be changed? Ideally I don't want to dig mega deep if not needed.

The area to be laid is only for light use. People only with no heavy traffic

Thanks in advance for any help.

Cheers

J

[lemoncurd1702]

If your on sand you probably don't need the geotextile. Sub-base is fine if its just for pedestrian use, as is bedding layer. wack the sand then sub-base. The fall maybe bit shallow though with cobbles/cubes which are somewhat irregular and more difficult to achieve a decent profile.

I love sandy soils, mostly clay here with those rocks that look really small on top but then descend about 2ft into ground:(.

[Tony McC]

Sandy soils tend to have a higher CBR than clay so don't worry about that.

Can't figure out what purpose is served by the geo-textile, and 75mm sub-base with 50mm bed is the very absolute bare minimum depth for either layer. You'd be much better off laying onto just 100mm of concrete and not bother with the sub-base as the sub-grade (the sandy soil) should be more than adequate for a ped-only construction.

Keep the joints tight - nothing more than 12mm ideally