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Dave
 
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Default When to use sharp sand and when to use "soft" sand?

I've always been unsure about when to use the different types of sand.
Obviously it's sharp sand for screed and builders sand for bricklaying
mortar but can someone tell me why? I'm about to bed a shower tray with
mortar (per manufacturers instructions) but can't decide whether to use
sharp sand or builders sand - ?

Dave
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andrewpreece
 
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"Dave" wrote in message
...
I've always been unsure about when to use the different types of sand.
Obviously it's sharp sand for screed and builders sand for bricklaying
mortar but can someone tell me why? I'm about to bed a shower tray with
mortar (per manufacturers instructions) but can't decide whether to use
sharp sand or builders sand - ?

Dave


I think it's to do with workability: soft sand has many grades of rounded
particles, right down to clay. This makes it handle well and you can adjust
bricks easily, the mortar made with soft sand supports the bricks but allows
plenty of movement if you need it.

Sharp sand has angular grains, less gradation, and I believe makes a
stronger
mortar, but it won't handle well or have the range of adjustment that
soft-sand
mortar does. My experience with soft-sand is very limited, but I have a fair
bit
with sharp sand, and found that if you didn't get the thickness off mortar
right
first time when bricklaying or laying paving stones on a solid bed of
mortar,
then if you tap the brick/paving down only a limited amount of adjustment
occurs
before it locks up solid, then it's take the brick/slab up and start again.
It also
allegedly doesn't handle well on a trowel. I built a wall using sharp sand
as I wanted
white mortar, and the local sharp sand is silver, but it wasn't easy.

Supposedly mortar can be made to handle better by using a plasticiser, which
is
either lime, or a proprietary plasticiser, like PVA or Febmix ( or squeezy
if you're
a cheapo! ).

I'm not an expert, but bedding something like a shower tray makes me think a
mortar that allows a goodly amount of adjustment is best, so I'd try the
soft sand.
There is a special cement for bricklaying, masonry cement, that does not
need
additional plasticiser, but if you're using ordinary Portland cement, I
think some
lime or plasticiser added to the mix will be beneficial ( e.g. 1:1:6
lime/cement/sand ).

PS: I defer to anyone else who's had years of experience in the trade and
knows
better!

Andy.



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Alex
 
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Sharp sand is used for renders and screeds,also used dry for bedding block
paving and slabs.


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Sand and glass are not really the same thing, though sand is used in
the manufacture of glass. Sand is mostly the crystalline form of
silicon dioxide known as quartz. The yellow/brown colouring comes
mostly from iron oxides. Glass is made by melting sand with sodium and
other metallic compounds and then supercooling it to form a
non-crystalline solid. Glass is not nearly as hard as quartz but the
main reason for not using it as an aggregate is that it is much more
valuable than sand.

Unless you are being paid for how many zillion bricks per hour you can
lay, sharp sand is perfectly good enough for building and the mortar
will indeed be stronger than with soft sand. More importantly, if you
want to be on the side of the angels, don't use Ordinary Portland
Cement at all. Build with lime mortar, a 3:1 sand : lime mix. The
best lime to use comes wet in a plastic tub and is called lime putty
but a cheaper alternative is the bagged hydrated lime available from
all buildres' merchants. Buy it from a merchant with a rapid turnover
and empty the bag into a plastic dustbin of water as soon as possible
and then use it wet because the lime cabonates on contact with the air.

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Rick
 
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On Fri, 27 May 2005 21:39:19 +0000 (UTC), Dave
wrote:

I've always been unsure about when to use the different types of sand.
Obviously it's sharp sand for screed and builders sand for bricklaying
mortar but can someone tell me why? I'm about to bed a shower tray with
mortar (per manufacturers instructions) but can't decide whether to use
sharp sand or builders sand - ?

Dave


Have you come accross "washed sand" yet ?

Rick

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Stuart Noble
 
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"Rick" wrote in message
...
On Fri, 27 May 2005 21:39:19 +0000 (UTC), Dave
wrote:

I've always been unsure about when to use the different types of sand.
Obviously it's sharp sand for screed and builders sand for bricklaying
mortar but can someone tell me why? I'm about to bed a shower tray with
mortar (per manufacturers instructions) but can't decide whether to use
sharp sand or builders sand - ?

Dave


Have you come accross "washed sand" yet ?


Yeah, I washed some building sand the other day. What stayed suspended in
the water was a surprisingly large amount of something called limonite,
which is a kind of clay tinted with yellow oxide.


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Stuart Noble
 
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wrote in message
ups.com...
Sand and glass are not really the same thing, though sand is used in
the manufacture of glass. Sand is mostly the crystalline form of
silicon dioxide known as quartz. The yellow/brown colouring comes
mostly from iron oxides. Glass is made by melting sand with sodium and
other metallic compounds and then supercooling it to form a
non-crystalline solid. Glass is not nearly as hard as quartz but the
main reason for not using it as an aggregate is that it is much more
valuable than sand.

Unless you are being paid for how many zillion bricks per hour you can
lay, sharp sand is perfectly good enough for building and the mortar
will indeed be stronger than with soft sand. More importantly, if you
want to be on the side of the angels, don't use Ordinary Portland
Cement at all. Build with lime mortar, a 3:1 sand : lime mix. The
best lime to use comes wet in a plastic tub and is called lime putty
but a cheaper alternative is the bagged hydrated lime available from
all buildres' merchants. Buy it from a merchant with a rapid turnover
and empty the bag into a plastic dustbin of water as soon as possible
and then use it wet because the lime cabonates on contact with the air.


And keep your work covered for how long to protect it from the rain?


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I'm tempted to say that washed sand is what you get when you add a dash
of washing up liguid to the mortar to make it easier to work. Really
it means that there is little or no clay and silt mixed in with the
sand. This is not neccessarily an advantage. When making mortar with
sand and lime, as oposed to Portland cement, a sound mortar can be
obtained with less lime if there is some silt and clay in the
aggregate.

Limonite it not a kind of clay but is a hydrated iron oxide, usually
amorphous or cryptocrystalline and often closely combined with
colloidal silica, phosphates, clay minerals and organic decomposition
products. It's a product of the weathering of iron bearing minerals
and is responsible for mush of the yellow/brown colour of sand.
There's not much limonite in silver sand!

Geological pedant.

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Mike
 
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wrote in message
...
On Sat, 28 May 2005 00:08:15 +0100, "andrewpreece"
wrote:


Sharp sand has angular grains, less gradation, and I believe makes a
stronger
mortar, but it won't handle well or have the range of adjustment that
soft-sand


Is there any reason why graded crushed glass couldn't be used in
admixture with sharp sand?


It is for insulating renders on houses needing a breathable insulating layer
outside.


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Stuart Noble
 
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wrote in message
oups.com...
I'm tempted to say that washed sand is what you get when you add a dash
of washing up liguid to the mortar to make it easier to work. Really
it means that there is little or no clay and silt mixed in with the
sand. This is not neccessarily an advantage. When making mortar with
sand and lime, as oposed to Portland cement, a sound mortar can be
obtained with less lime if there is some silt and clay in the
aggregate.

Limonite it not a kind of clay but is a hydrated iron oxide, usually
amorphous or cryptocrystalline and often closely combined with
colloidal silica, phosphates, clay minerals and organic decomposition
products. It's a product of the weathering of iron bearing minerals
and is responsible for mush of the yellow/brown colour of sand.


It's the only time I've seen oxides freely suspended in water, which
suggests the particles must either be incredibly small, or they are
balanced
by some or all of the combination products above.
If the oxide content of limonite were higher it wouild presumably have a
commercial value as an ochre.

Geological pedant.

Any geologist is better than none.


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Limonite, FeO.OH.nH2O is the main ingredient of yellow ochre pigment
but this may also include the less hydrated minerals, Goethite and
Lepidcrocite, which both have the composition FeO.OH and produce
darker, more opaque pigments.

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The Natural Philosopher
 
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Andrew Gabriel wrote:

In article ,
writes:

I continue to ask as my local council has a problem disposing of
coloured glass, it going to landfill. There is a market for clear
glass but even this does not cover collection costs if my local
authority is correct.



Glass really wasn't worth recycling at all until the landfill
tax came in. If you have to start your car engine in order to
participate in glass recycling, then it's almost certainly still
not worth it. "Driving to the bottle bank" is an expression which
is sometimes used to refer to pointless recycling. People are
looking around for uses for coloured glass, and new road surfaces
is something they are being used on, but I think that's still
experimental. Manufacturing and using less coloured glass in the
first place is probably a better bet, but people seem to like
trying to solve problems at the wrong end of the supply chain.

Paper is another questionable one. The cost (in particular the
energy use) of processing recycled paper often exceededs the
cost of creating new paper. It has always seemed to me that
paper should be buried in landfill as this is exactly the reverse
process of burning fossil fuels, i.e. it's taking CO2 out of the
atmosphere and burying it back underground. Actually, planting
fast growing plants, harvesting them, and burying them down old
coal mines could be quite a good thing to do from this perspective.


I like the idea of it. Perhaps we could go onto lots of wbesites and
request catalogues to be sent to 'shaft 6, The Old Tin Mine, Trefryw, S
Wales'

;-)
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The Natural Philosopher
 
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wrote:

On 05 Jun 2005 15:55:09 GMT,
(Andrew
Gabriel) wrote:


Glass really wasn't worth recycling at all until the landfill
tax came in.



I'll not disagree but given the "need" to avoid landfill and ongoing
quarrying/dredging for sand it just struck me as a possible use
without too much recycling cost.

Paper is another questionable one. The cost (in particular the
energy use) of processing recycled paper often exceededs the
cost of creating new paper. It has always seemed to me that
paper should be buried in landfill as this is exactly the reverse
process of burning fossil fuels, i.e. it's taking CO2 out of the
atmosphere and burying it back underground.



I'll agree this with the possible exception of glossy papers which
have lots of china clay in them, I wonder if this filler can be washed
out and reclaimed?

This is a bit of my hobby horse because use of recycled fiber impacted
on my erstwhile trade. In the 70s we harvested the portion of the crop
that was "pulpwood" at a profit. As GATT and recycling bit we needed
to cross subsidise harvesting this with the better grades, now with
mechanised harvesting a lot gets left in the wood.

I disagree about burying it though, if anaerobic conditions occur
biogas is given off and this has implications for damaging the ozone
layer as well as being a worse climate changing gas than the CO2 that
would be generated by burning it.

Now if you consider pyrolysing it to 85% fixed carbon and then
burying it.....

I also cannot see the benefit in recycling simple (non halogenated)
plastics over burning them for power, more a topic for the environment
newsgroups though.

Totally agree.

And as far as landfill sites - or their lack - goes - why not use glass
banks to shore up the east coast, bits of which keep falling into the
sea...?


AJH

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Andrew Gabriel wrote:
In article ,
atmosphere and burying it back underground. Actually, planting
fast growing plants, harvesting them, and burying them down old
coal mines could be quite a good thing to do from this perspective.


And when the soil has been denuded of all nutrients, what then? Or
local water courses are polluted from nitrate run off due to
fertilising said crops?

Seems like a paticularly stupid idea to me.

MBQ

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Posts: 2
Default When to use sharp sand and when to use "soft" sand?

replying to biff, chris wrote:
silica sand is glass, used for ashlar . sharp sand contains glass but a not
as much. 3:1 ratio is okay for walls and low level renders/pointing. exposed
areas need something stronger. 2.2:1 lime to sand ( add a tiny wee bit cement
to the mix ) any st astiars nhl (except 5) will work greatly. you can buy pre
mix 25 kg for £12.50. fine sand or coarse ( fine for pointing/rendering less
than 5mm) . just add water. adhesion is exceptional and it sets very
quickly. its bombproof!!! otherwise general building ...... sharp, sand,
tradiblanc nhl (35 kg) but be aware, tradi sets very light so use a dark sand
or add pigment and defiantly carry out a wee trial.patch

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