We want to build a limestone path that will be packed underneath with gap7. the area needs to drain off water so were wondering how well gap 7drains when compacted.
ebygum1,
Oct 19, 2:29pm
Gap 7 is quite small,not much more than crusher dust. Try gap 40.
tintop,
Oct 19, 3:50pm
It really depends on the grading curve. Any crushed aggregate mix regardless of top size will be impervious if there are excessive silt and clay fines at the lower sized end of the grading.
The 'G' ( General ) range of aggregates do not have strict controls over the gradings, and it largely depends on the quarry that the produces the product.
Builders Mix ( say BM20) will be ok, as will PAP7 ( which is an aggregate specifically produced for builders mix and ready mixed concrete, contains no silt or clay fines at all ) will be ok too. But expensive, and difficult to compact and unstable due to lack of fines :)
All in all - GAP40, or GAP20 would be a reasonable compromise.
G = General A = All P= Passing or Premier
( and there are more . )
fordcrzy,
Oct 20, 2:04am
gap20/40 wont work as the base of a path.
tintop,
Oct 20, 6:15am
Oh? Why not?
ebygum1,
Oct 20, 3:40pm
Bugger, I've been doing it wrong for over 50 years.
tintop,
Oct 20, 4:00pm
Same! lol
fordcrzy,
Oct 20, 5:55pm
The lime chip is just gonna go down into the gap 40 wont it? or do you put mat between the layers. is only a footpath
ebygum1,
Oct 20, 6:15pm
No the chip will stay on top,biggest problem with using lime chip is when it is wet,you walk white footsteps onto other surfaces. A lot of lime chip is used around our town as it is quarried here and very cheap to buy.
tintop,
Oct 20, 9:57pm
Ah! I think I see what you are getting at :)
GAP ( as in GAP40) does not mean 'gap' as in a space, it means it is a G??eneral mixed aggregate that will A??ll P??ass through a sieve size of 4??0??mm
When compacted as a base, it will present a smooth surface without any 'gaps' , especially after a few passes of a vibrating plate compactor.
However it needs to be placed in position and not excessively raked, otherwise the finer material will be left behind and the top size stones will segregate and you will be left with a bony ( gappy) surface. Use the back of the rake rather than the tynes to level out the minor hills and hollows. Avoid letting it dry out until after compacting.
fordcrzy,
Oct 21, 1:45am
sorry the reason i asked was i got some gap40 a few years ago for a french drain and it had bugger all fines in it and certainly wouldnt have been suitable as a base for anything "solid"
tintop,
Aug 25, 12:17pm
Yes - some places do not manage their stockpiles properly.
It should be a blend from its max size down to sand./silt
If it looks 'boney' in the stockpile ( most commonly at the bottom outside of the heap) - get the loader driver to give it a bit of a mix up.
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