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Posted: Sun Feb 02, 2014 4:53 pm
by JonJ
I've been working my way through many pages on this site. It's a fantastic resource! Much appreciated!
I've had grano recommended for different applications, including:
- granolithic concrete for bedding flags
- grano dust as the bedding layer for sand. (One contractor suggested this, saying that water percolating between blocks can cause sand to be washed away, but I wonder whether he had used building sand, and not sharp sand.)
TP list 3 types of grano:
- grano 6mm dust (the usual form of grano?)
- grano 6mm ("washed grano"?)
- grano dust (the dust removed when washing grano?)
So my questions are:
- Would it be sensible to use grano for these applications?
- If so, which type should I use in each case?
Jon
Posted: Mon Feb 03, 2014 10:05 am
by Tony McC
Grano 6mm to dust is the usual form and the most useful for mortar applications as shown on the Mixing Grano page.
Washed grano has reduced fines but unless the grading is declared (are all the fines gone, or just the <63µm stuff, or do they not actually know?) I'd be wary of using it.
Grano dust is often the same as 6mm to dust. It was always known as 'Grano Dust' in some parts, even though some of the particles were patently not dust! But again, it comes down to a declaration. To me, a dust has to be >1mm or what would be termed 0/1 in the modern Euro-bollocks parlance. However, rubbing a handful would reveal its true character and, if it is a mix of sizes from, say, 4mm down, then it would be OK for mortar use.
I know grano does get used as an unbound bedding material but whay? It's two or three times the cost of grit sand and brings nothing extra in the way of handling or compaction. You contractor who claim water percolating between blocks (reckoned to be 2% of surface water at most) will wash away the bedding is either an eejit or is using the wrong type of sand. The correct grading of sand is specified because it shows best resistance to sub-surface movement of water.
So: grano for mortar applications is fine but unbound grano for bedding is a nonsense.
Posted: Mon Feb 03, 2014 9:36 pm
by lemoncurd1702
I'd never heard of grano until recently (on this site) and if I asked a merchant for it here in S.Wales he'd offer me some breakfast cereal. If I ask for dust or stone dust then fine. It's about 6mm down and mostly limestone.
What I want to know if this is the same stuff as grano.
The reason many use it down this way, besides the misguided belief that its better than sharp sand, is that it's cheaper. About £10/T collected from the quarry, £20 if collected from merchants as loose material, in bulk bags it's around the same price as sand.
Posted: Mon Feb 03, 2014 10:43 pm
by JonJ
Tony McC wrote:So: grano for mortar applications is fine but unbound grano for bedding is a nonsense.
Thank you for all the information - it's very helpful. And I can see the sense in your conclusion.
Posted: Mon Feb 03, 2014 10:47 pm
by JonJ
lemoncurd1702 wrote:What I want to know if this is the same stuff as grano.
The reason many use it down this way, besides the misguided belief that its better than sharp sand, is that it's cheaper. About £10/T collected from the quarry, £20 if collected from merchants as loose material, in bulk bags it's around the same price as sand.
I understand that what is sold as "grano" is often made from limestone.
It's interesting what you say about the cost relative to sand. I'll check on that locally.
Posted: Tue Feb 04, 2014 11:48 am
by Tony McC
The grano we see in Northern England and Southern Scotland (I have seen it in that Essex on one occasion) is a very specific, hard, grey-green limestone that comes from near Carnforth on the Lancashire/Cumbria border.
I used some just before Christmas and it had been bulked out with crushed brick and another source looked like crushed whin. I suppose that the economics of quarrying primary aggregates means that lesser materials are now deemed acceptable.
I think the use of stone dust in South Wales stems from the lack of an economically-viable local sharp sand. Sometimes it's easy to forget how lucky we are in NW England with our abundant supply of excellent sands, gravels, road-building aggs and building/paving stone.
Posted: Tue Feb 04, 2014 4:33 pm
by lutonlagerlout
similar scenario here lots of sand pits equals cheap good sand
but type 1 crushed limestone or granite has to be ferried in by train therefore adding to the cost
LLL
Posted: Tue Feb 04, 2014 6:14 pm
by GB_Groundworks
used some today to mix some granolithic mortar to bed some 110mm pipe in concrete floor wed cut out. love the stuff 
i always chuck 1 sand in to my mix as per the soften pit on tonys link
Edited By GB_Groundworks on 1391537798
Posted: Tue Feb 04, 2014 6:50 pm
by lemoncurd1702
Tony McC wrote:I think the use of stone dust in South Wales stems from the lack of an economically-viable local sharp sand. Sometimes it's easy to forget how lucky we are in NW England with our abundant supply of excellent sands, gravels, road-building aggs and building/paving stone.
I dunno Tony, we're pretty near the coast here and there's still plenty of sand out in the Bristol channel.
Which is of much concern to environmentalists, and I am partly inclined to agree with them. But one has to earn a living and can only use whats available.
It would be interesting to know though, what the varying costs of raw materials are from region to region.
In S.Wales most of the well known merchants are around £30-£35+vat for bulk bags of most sands and aggregates, barring decorative agg.
Large quantities of sand will cost about £17.50/T+vat including delivery for minimum of either 11T, 16T or 20T loads and sub-base around £13/T+vat.
Posted: Tue Feb 04, 2014 8:13 pm
by digerjones
lemoncurd1702 wrote:Tony McC wrote:I think the use of stone dust in South Wales stems from the lack of an economically-viable local sharp sand. Sometimes it's easy to forget how lucky we are in NW England with our abundant supply of excellent sands, gravels, road-building aggs and building/paving stone.
I dunno Tony, we're pretty near the coast here and there's still plenty of sand out in the Bristol channel.
Which is of much concern to environmentalists, and I am partly inclined to agree with them. But one has to earn a living and can only use whats available.
It would be interesting to know though, what the varying costs of raw materials are from region to region.
In S.Wales most of the well known merchants are around £30-£35+vat for bulk bags of most sands and aggregates, barring decorative agg.
Large quantities of sand will cost about £17.50/T+vat including delivery for minimum of either 11T, 16T or 20T loads and sub-base around £13/T+vat.
they are the sort of prices i pay in south cheshire/ shropshire/staffordshire boader
Posted: Wed Feb 05, 2014 11:38 am
by Tony McC
We used to get 5 tonnes of so of grano dropped on a job if we were doing the 'roads-and-sewers' and feed from it as we built the manholes and drag-outs which needed benching.
After a pile had been stood for a month or so, it started to self-bind and you'd need to loosen it with a pick before shovelling it into the mixer. I often wonder why it wasn't more widely used as a self-binding surface for pathways and the like. I can only think that the turquoise colour isn't to everyone's taste!