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Posted: Thu Jan 23, 2014 2:48 pm
by kariba
Any West Aussies can enlighten me about sub base?
Posted: Fri Jan 24, 2014 9:30 am
by Tony McC
I'm not an Aussie but my understanding from a good mate who spent twenty years working in the Australian paving industry and even married one of y0ur shiela-ladies, is that it's more or less the same as what's used in Britain and Ireland.
Posted: Fri Jan 24, 2014 3:16 pm
by kariba
I'm English Tony, moved here about 8 years ago. I'm in WA which is built on ancient sand dunes, I hear so much crap from contractors about how you don't require a sub-base. I went for a job interview at a big civil landscape environmental company, million dollar projects, same deal block/brick paving laid on brickies sand only.
I'm sticking to my guns, the only thing I cold find was that in sandy on non reactive sub grades the sub-base may be reduced on pedestrian areas. What does CBR stand for?
Posted: Sat Jan 25, 2014 9:51 am
by Carberry
kariba wrote:I'm English Tony, moved here about 8 years ago. I'm in WA which is built on ancient sand dunes, I hear so much crap from contractors about how you don't require a sub-base. I went for a job interview at a big civil landscape environmental company, million dollar projects, same deal block/brick paving laid on brickies sand only.
I'm sticking to my guns, the only thing I cold find was that in sandy on non reactive sub grades the sub-base may be reduced on pedestrian areas. What does CBR stand for?
CBR is the california bearing ratio, it's a test for the quality of sub grade and compaction. They take a sample of the sub grade, stick it in a mould then apply pressure to it, they then measure how far it penetrates the sample.
Posted: Sat Jan 25, 2014 11:28 am
by Tony McC
Even on high CBR value, gravelly sub-grades, a properly constructed sub-base evens out any irregularity.
If the locals are getting away with no sub-base, then you will be under enormous pressure to compete with them on their own terms, but as an alternative, you could splurge a few hundred dollars on the a copy of Aussie Standards and advertise your work as being fully compliant, in the hope that clients would be happier paying a premium for the peace-of-mind such work provides.
Posted: Sat Jan 25, 2014 3:13 pm
by kariba
Cheers lads, the most annoying thing is the evidence is all around. Random sunken areas, channelization, edges falling away. I drove through a fairly new town center on a block paved road, it was like driving over small speed bumps!
Every shire requires a sub-base, most of the specifications are on the net but most of them seem to get away with it. Wouldn't this method make it very difficult to compact to refusal?
???
Posted: Sat Jan 25, 2014 5:48 pm
by TheRockConcreting
In oz it's all about the concrete, they nearly always do without a proper sub-base, just normally drop in abit of crusher dust to make up the levels, it's alot lower strength aswell, C20 is standard for drives. Where in england its C30.
A hi-spec block paving job is blocks on 100mm of crete without a sub-base.
Its sound odd but i have personally driven 30 ton trucks over plenty of 100mm no sub drives in oz and they have all held up without any sign of a crack, but over here in england driving the same type of 30 ton truck over 100mm drives and it cracks straight away!
Posted: Sat Jan 25, 2014 8:46 pm
by kariba
For pedestrian traffic over east I would lay 80mm conc with mesh and lay on 20mm of mortar then wet grout. Most of the paving in Melbourne is bluestone. In perth most of the people look at me like I'm from another planet when I tell them that. :O
Posted: Mon Jan 27, 2014 3:47 pm
by kariba
TheRockConcreting wrote:In oz it's all about the concrete, they nearly always do without a proper sub-base, just normally drop in abit of crusher dust to make up the levels, it's alot lower strength aswell, C20 is standard for drives. Where in england its C30.
A hi-spec block paving job is blocks on 100mm of crete without a sub-base.
Its sound odd but i have personally driven 30 ton trucks over plenty of 100mm no sub drives in oz and they have all held up without any sign of a crack, but over here in england driving the same type of 30 ton truck over 100mm drives and it cracks straight away!
what part of Aus?
Posted: Mon Jan 27, 2014 5:15 pm
by TheRockConcreting
Qld