Compacting sub base - Some areas still loose

mcelec · Post: # 38266Post **mcelec** Fri May 29, 2009 5:41 pm

ive wacked my sub base down (gone over it at least 9 passes) but in the areas where there doesnt seem to be a lot of fines the sub base can be loosened by foot, what is the best way to combat this? would i be ok to put some grit sand over these areas and compact before adding the bedding layer?

Mainland · Post: # 38267Post **Mainland** Fri May 29, 2009 5:48 pm

You have hit the problem on the head. No fines means no compaction. I would recommend that you dig up the affected area and re-lay so that the fines are mixed again. Also, if you are compacting when the material is bone dry it will not compact. Try watering the area and then leaving for a while until the water has soaked in. When the ground is just damp (not waterlooged) try compacting again.

mcelec · Post: # 38269Post **mcelec** Fri May 29, 2009 6:31 pm

this is probably a daft question but can i not buy a small bag of fines to put over the area in question and compact that area?

Big Phil · Post: # 38281Post **Big Phil** Fri May 29, 2009 8:06 pm

no. you need to dig the area up as recommended and mix in thoroughly.

Post: # 38300Post **seanandruby** Sat May 30, 2009 7:06 am

Is it a large area? maybe you could lay a sheet of terran, if its too much ???

mcelec · Post: # 38305Post **mcelec** Sat May 30, 2009 9:01 am

seanandruby wrote:Is it a large area? maybe you could lay a sheet of terran, if its too much ???

there is about three areas about 1m2, if i have to dig it up then so be it i just wanted to try and avoid disturbing the base after spending so long getting it to the correct level, what i had hoped to do was put a smaller stone over the area like white spar and re-compact, if i put put a drive-way fabric like geo textile over the area before adding sand will that help? i know it will stop the sand filtering into the gaps in the stone but will the gaps in the stone eventually allow movement in the sub base over time changing the surface level of my paving?

Mainland · Post: # 38312Post **Mainland** Sat May 30, 2009 11:49 am

Terram/Geo-textile should be used between the sub-grade (the ground) and the sub-base (e.g.type 1). It is used to prevent the sub-base mixing with the underlying ground.

Big Phil · Post: # 38318Post **Big Phil** Sat May 30, 2009 1:57 pm

unfortunately by dressing the top with fines all you end up doing is making the surface look 'nice' and you're not providing any structural strength to the affected areas.

Post: # 38319Post **seanandruby** Sat May 30, 2009 4:10 pm

I beg to differ. Geotextile acts as a barrier betwixt sub base, or bedding to sub base. it also "strenghthens" it somewhat. I have used it between both capping and subase, also sub base and bedding. It wont hurt to scatter sharp sand into the boney parts of sub base and wack it. It is a poor day that we have to take up and re-lay metres of material, i know i could'nt afford the time and material wastage. :;):