Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
sand.

I had to crush some of the portland cement because it's a bit old and 
some of has gone hard, but not rock hard. I used a rolling pin.

I'm having to chisel out the concrete now and make up a new mix. I 
notice that when I'm chiseling the concrete out that I made, it easy 
turns to powder. My house has concrete/pebble walls and I must chisel 
out and plug with concrete for shelving.

I'm miffed and not slightly confused why the mix I made turned out so 
poor. Next time I'll use 2 sand, 1 cement.

"Rich"  wrote in message 
news:6e1phgF4u3ctU1@mid.individual.net...
> Well, I thought 3 parts sand and 1 part cement would be okay, but no. It's 
> too sandy by far. I'm sure I put in 3 levels of cement and 9 of sand.
>
> I had to crush some of the portland cement because it's a bit old and some 
> of has gone hard, but not rock hard. I used a rolling pin.
>
> I'm having to chisel out the concrete now and make up a new mix. I notice 
> that when I'm chiseling the concrete out that I made, it easy turns to 
> powder. My house has concrete/pebble walls and I must chisel out and plug 
> with concrete for shelving.
>
> I'm miffed and not slightly confused why the mix I made turned out so 
> poor. Next time I'll use 2 sand, 1 cement.


Use NEW cement FFS!

"RW"  wrote in message
news:6e1ptiF4um4iU1@mid.individual.net...
>
> "Rich"  wrote in message
> news:6e1phgF4u3ctU1@mid.individual.net...
>> Well, I thought 3 parts sand and 1 part cement would be okay, but no.
>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of
>> sand.
>>
>> I had to crush some of the portland cement because it's a bit old and
>> some of has gone hard, but not rock hard. I used a rolling pin.
>>
>> I'm having to chisel out the concrete now and make up a new mix. I
>> notice that when I'm chiseling the concrete out that I made, it easy
>> turns to powder. My house has concrete/pebble walls and I must chisel
>> out and plug with concrete for shelving.
>>
>> I'm miffed and not slightly confused why the mix I made turned out so
>> poor. Next time I'll use 2 sand, 1 cement.
>
>
> Use NEW cement FFS!


Does cement "go off?

I mean, I can crush these clumped up bits to powder, because they are
fairly soft. But is the cement now practically useless even when ground
down?

In article ,
	"Rich"  writes:
> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
> sand.

3:1 is a very strong mix. There aren't many applications where
that would be suitable.

> I had to crush some of the portland cement because it's a bit old and 
> some of has gone hard, but not rock hard. I used a rolling pin.

That means the cement has partially set, so you actually have a
cement bag containing a mixture of inert dust and cement, the
proportions of which are unknown. Just because you broke it
apart doesn't mean it's capable of setting a second time.

> I'm having to chisel out the concrete now and make up a new mix. I 
> notice that when I'm chiseling the concrete out that I made, it easy 
> turns to powder. My house has concrete/pebble walls and I must chisel 
> out and plug with concrete for shelving.

Where does the concrete come into it? You described making
mortar, not concrete.

> I'm miffed and not slightly confused why the mix I made turned out so 
> poor. Next time I'll use 2 sand, 1 cement. 

Because your cement has gone off, and/or because you didn't allow
enough time for it to set fully (about 6 weeks).

1) Chuck out the bag of gone-off cemnent.
2) Describe the wall construction in more detail.
3) Specify age of house, and location, so we have some idea
   how it might have been constructed.

Then people can help you by suggesting what you should be
using (which might not be cement at all, but certainly won't
be a 2:1 or 3:1 mortar mix).

-- 
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Rich wrote:
> 
> "RW"  wrote in message
> news:6e1ptiF4um4iU1@mid.individual.net...
>>
>> "Rich"  wrote in message
>> news:6e1phgF4u3ctU1@mid.individual.net...
>>> Well, I thought 3 parts sand and 1 part cement would be okay, but no.
>>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of
>>> sand.
>>>
>>> I had to crush some of the portland cement because it's a bit old and
>>> some of has gone hard, but not rock hard. I used a rolling pin.
>>>
>>> I'm having to chisel out the concrete now and make up a new mix. I
>>> notice that when I'm chiseling the concrete out that I made, it easy
>>> turns to powder. My house has concrete/pebble walls and I must chisel
>>> out and plug with concrete for shelving.
>>>
>>> I'm miffed and not slightly confused why the mix I made turned out so
>>> poor. Next time I'll use 2 sand, 1 cement.
>>
>>
>> Use NEW cement FFS!
> 
> 
> Does cement "go off?
> 
> I mean, I can crush these clumped up bits to powder, because they are
> fairly soft. But is the cement now practically useless even when ground
> down?
> 

sort of. Essentially half of that ground up crap has set. So its not 
cement, its a weak sand. Which is why you needed more..

Rich wrote:
> "RW"  wrote in message
> news:6e1ptiF4um4iU1@mid.individual.net...
>>
>> "Rich"  wrote in message
>> news:6e1phgF4u3ctU1@mid.individual.net...
>>> Well, I thought 3 parts sand and 1 part cement would be okay, but
>>> no. It's too sandy by far. I'm sure I put in 3 levels of cement and
>>> 9 of sand.
>>>
>>> I had to crush some of the portland cement because it's a bit old
>>> and some of has gone hard, but not rock hard. I used a rolling pin.
>>>
>>> I'm having to chisel out the concrete now and make up a new mix. I
>>> notice that when I'm chiseling the concrete out that I made, it easy
>>> turns to powder. My house has concrete/pebble walls and I must
>>> chisel out and plug with concrete for shelving.
>>>
>>> I'm miffed and not slightly confused why the mix I made turned out
>>> so poor. Next time I'll use 2 sand, 1 cement.
>>
>>
>> Use NEW cement FFS!
>
>
> Does cement "go off?

Yes

> I mean, I can crush these clumped up bits to powder, because they are
> fairly soft. But is the cement now practically useless even when
> ground down?

Yes.

Now. what were you doing with a 1:3 mix of cement and sand?

As this is not classed as a concrete mix but a mortar.

A concrete mix would be 1:3:4.

I.E. 1 part cement, 3 parts sand and 4 parts chippings - of varying grades 
dependant upon the job in hand.

Also, the amount of water used will have an effect on the strength - as will 
the water content of the sand. Too much water = a weak mix of concrete

Tanner-'op

In article ,
   Rich  wrote:
> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
> sand.

3:1 is far too strong for most things.

> I had to crush some of the portland cement because it's a bit old and 
> some of has gone hard, but not rock hard. I used a rolling pin.

You have your answer. Cement goes off with age - and is so cheap it's not
worth keeping.

-- 
*I used to have an open mind but my brains kept falling out *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

On Tue, 15 Jul 2008 00:23:03 +0100, "Dave Plowman (News)"
 wrote:

>In article ,
>   Rich  wrote:
>> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
>> sand.
>
>3:1 is far too strong for most things.

Ok - I've been reading this thread - know <0 about cement/mortar, but
trying to learn a bit. This has got 2B a stupid question, but how can
the mix be "*too strong* for most things".  Too weak I could
understand - but too strong! Please explain.

In article ,
   dave  wrote:
> On Tue, 15 Jul 2008 00:23:03 +0100, "Dave Plowman (News)"
>  wrote:

> >In article ,
> >   Rich  wrote:
> >> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
> >> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
> >> sand.
> >
> >3:1 is far too strong for most things.

> Ok - I've been reading this thread - know <0 about cement/mortar, but
> trying to learn a bit. This has got 2B a stupid question, but how can
> the mix be "*too strong* for most things".  Too weak I could
> understand - but too strong! Please explain.

For example. If you use too strong a mix when bricklaying any movement
will cause the bricks to crack.

-- 
*I never drink anything stronger than gin before breakfast *

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

On Jul 15, 1:16 am, "Dave Plowman (News)" 
wrote:
> In article ,
>    dave  wrote:
>
> > On Tue, 15 Jul 2008 00:23:03 퍝, "Dave Plowman (News)"
> >  wrote:
> > >In article ,
> > >   Rich  wrote:

> > >> Well, I thought 3 parts sand and 1 part cement would be okay, but no> > >> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of
> > >> sand.
>
> > >3:1 is far too strong for most things.
> > Ok - I've been reading this thread - know <0 about cement/mortar, but
> > trying to learn a bit. This has got 2B a stupid question, but how can
> > the mix be "*too strong* for most things".  Too weak I could
> > understand - but too strong! Please explain.
>
> For example. If you use too strong a mix when bricklaying any movement
> will cause the bricks to crack.

Mortar should be weaker than brick, then any movement breaks the
mortar not bricks.


NT

dave wrote:
> On Tue, 15 Jul 2008 00:23:03 +0100, "Dave Plowman (News)"
>  wrote:
> 
>> In article ,
>>   Rich  wrote:
>>> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
>>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
>>> sand.
>> 3:1 is far too strong for most things.
> 
> Ok - I've been reading this thread - know <0 about cement/mortar, but
> trying to learn a bit. This has got 2B a stupid question, but how can
> the mix be "*too strong* for most things".  Too weak I could
> understand - but too strong! Please explain.

Actually strength reduces with pure portland cement.


The ideal water resistant mix is where the holes between the grains of 
sand are completely filled with fine cement. Thats a 'strong' mix and is 
used underground and below damp according to my brickies, so that it 
wont split with frost: instead the bricks will....haha. Nothing to do 
with the mortar though. porous bricks below damp (or in driving rain)+ 
frost = spalling.

Weaker than that between 2:1 and about 5:1 the mortar becomes less full 
of cement, and air pockets replace the cement between the sand grains.

Enough to make it quite permeable. Like most bricks are, so its reckoned 
to be no worse than the bricks in terms of general waterproofness. The 
texture tends proggresivly from 'hard set muck' towards 'crunchy sand' 
as you go up the scale reaching crunchy sand with very little strength 
at about 7:1

Which is sort of what you might lay e.g. patio slabs on. The cement only 
being there to stop the sand washing away, without reducing drainage.

I've got a few cracks in my wall that I built where I didn't use ties. 
The cement is rock hard, but no bricks cracked by the way.

I have never seen a brick split by too strong cement yet. Maybe old, 
soft or very cheap bricks will tho.

The general reason to not use too strong a mix is firstly that it gets 
weaker beyond the sort of optimal 2:1 and secondly cement, whilst cheap, 
is still a whole lot more expensive than sand.

To be honest, there is a lot of merit in the view for general 
bricklaying, that the cement is there to stop the sand washing out, and 
the sand is there to keep the bricks apart ;-)

In this weather you mortar wont fully set for 2 days as far as general 
feel goes. After that it will set a bit harder in a few weeks.

On 15 Jul, 06:02, The Natural Philosopher <a...@b.c> wrote:
> dave wrote:
> > On Tue, 15 Jul 2008 00:23:03 +0100, "Dave Plowman (News)"
> >  wrote:
>
> >> In article ,
> >>   Rich  wrote:
> >>> Well, I thought 3 parts sand and 1 part cement would be okay, but no.
> >>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of
> >>> sand.
> >> 3:1 is far too strong for most things.
>
> > Ok - I've been reading this thread - know <0 about cement/mortar, but
> > trying to learn a bit. This has got 2B a stupid question, but how can
> > the mix be "*too strong* for most things".  Too weak I could
> > understand - but too strong! Please explain.
>
> Actually strength reduces with pure portland cement.
>
> The ideal water resistant mix is where the holes between the grains of
> sand are completely filled with fine cement. Thats a 'strong' mix and is
> used underground and below damp according to my brickies, so that it
> wont split with frost: instead the bricks will....haha. Nothing to do
> with the mortar though. porous bricks below damp (or in driving rain)+
> frost = spalling.
>
> Weaker than that between 2:1 and about 5:1 the mortar becomes less full
> of cement, and air pockets replace the cement between the sand grains.
>
> Enough to make it quite permeable. Like most bricks are, so its reckoned
> to be no worse than the bricks in terms of general waterproofness. The
> texture tends proggresivly from 'hard set muck' towards 'crunchy sand'
> as you go up the scale reaching crunchy sand with very little strength
> at about 7:1
>
> Which is sort of what you might lay e.g. patio slabs on. The cement only
> being there to stop the sand washing away, without reducing drainage.
>
> I've got a few cracks in my wall that I built where I didn't use ties.
> The cement is rock hard, but no bricks cracked by the way.
>
> I have never seen a brick split by too strong cement yet. Maybe old,
> soft or very cheap bricks will tho.
>
> The general reason to not use too strong a mix is firstly that it gets
> weaker beyond the sort of optimal 2:1 and secondly cement, whilst cheap,
> is still a whole lot more expensive than sand.
>
> To be honest, there is a lot of merit in the view for general
> bricklaying, that the cement is there to stop the sand washing out, and
> the sand is there to keep the bricks apart ;-)
>
> In this weather you mortar wont fully set for 2 days as far as general
> feel goes. After that it will set a bit harder in a few weeks.

Also, good mixing is important, especially for weaker mixes. If you
are trying for 5:1 for bricklaying and its not mixed well, you could
have parts at 7:1 which is too weak and / or will take too long to
set.
Simon.

"Tanner-'op" <tannerop@i......nvalid.com> wrote in message 
news:6e1r7fF4uvloU1@mid.individual.net...
> Rich wrote:
>> "RW"  wrote in message
>> news:6e1ptiF4um4iU1@mid.individual.net...
>>>
>>> "Rich"  wrote in message
>>> news:6e1phgF4u3ctU1@mid.individual.net...
>>>> Well, I thought 3 parts sand and 1 part cement would be okay, but
>>>> no. It's too sandy by far. I'm sure I put in 3 levels of cement and
>>>> 9 of sand.
>>>>
>>>> I had to crush some of the portland cement because it's a bit old
>>>> and some of has gone hard, but not rock hard. I used a rolling pin.
>>>>
>>>> I'm having to chisel out the concrete now and make up a new mix. I
>>>> notice that when I'm chiseling the concrete out that I made, it easy
>>>> turns to powder. My house has concrete/pebble walls and I must
>>>> chisel out and plug with concrete for shelving.
>>>>
>>>> I'm miffed and not slightly confused why the mix I made turned out
>>>> so poor. Next time I'll use 2 sand, 1 cement.
>>>
>>>
>>> Use NEW cement FFS!
>>
>>
>> Does cement "go off?
>
> Yes
>
>> I mean, I can crush these clumped up bits to powder, because they are
>> fairly soft. But is the cement now practically useless even when
>> ground down?
>
> Yes.
>
> Now. what were you doing with a 1:3 mix of cement and sand?
>
> As this is not classed as a concrete mix but a mortar.
>
> A concrete mix would be 1:3:4.
>
> I.E. 1 part cement, 3 parts sand and 4 parts chippings - of varying grades 
> dependant upon the job in hand.
>
> Also, the amount of water used will have an effect on the strength - as 
> will the water content of the sand. Too much water = a weak mix of 
> concrete
>
> Tanner-'op
>

Butting in here, as I too find the ratios in practice a bit hit and miss, 
and have to fight a strong tendency to add a bit more cement 'just to make 
sure':

Other comments seem to be hitting on about 5:1 sand to cement for mortar, 
but your ratio for concrete is essentially that same 'spoonful' of cement 
now extended to cover 7 'spoonfuls' of other stuff.  Is that really reliably 
enough?
 (before I resume trying to remake a large number of steps in the - very 
steep - garden, that are taking me a long time because of the surprisingly 
large quantities of materials involved...  I would not want to sit back and 
watch them all get gradually washed away afterwards!)

Cheers,
S

Spamlet wrote:
> "Tanner-'op" <tannerop@i......nvalid.com> wrote in message 
> news:6e1r7fF4uvloU1@mid.individual.net...
>> Rich wrote:
>>> "RW"  wrote in message
>>> news:6e1ptiF4um4iU1@mid.individual.net...
>>>> "Rich"  wrote in message
>>>> news:6e1phgF4u3ctU1@mid.individual.net...
>>>>> Well, I thought 3 parts sand and 1 part cement would be okay, but
>>>>> no. It's too sandy by far. I'm sure I put in 3 levels of cement and
>>>>> 9 of sand.
>>>>>
>>>>> I had to crush some of the portland cement because it's a bit old
>>>>> and some of has gone hard, but not rock hard. I used a rolling pin.
>>>>>
>>>>> I'm having to chisel out the concrete now and make up a new mix. I
>>>>> notice that when I'm chiseling the concrete out that I made, it easy
>>>>> turns to powder. My house has concrete/pebble walls and I must
>>>>> chisel out and plug with concrete for shelving.
>>>>>
>>>>> I'm miffed and not slightly confused why the mix I made turned out
>>>>> so poor. Next time I'll use 2 sand, 1 cement.
>>>>
>>>> Use NEW cement FFS!
>>>
>>> Does cement "go off?
>> Yes
>>
>>> I mean, I can crush these clumped up bits to powder, because they are
>>> fairly soft. But is the cement now practically useless even when
>>> ground down?
>> Yes.
>>
>> Now. what were you doing with a 1:3 mix of cement and sand?
>>
>> As this is not classed as a concrete mix but a mortar.
>>
>> A concrete mix would be 1:3:4.
>>
>> I.E. 1 part cement, 3 parts sand and 4 parts chippings - of varying grades 
>> dependant upon the job in hand.
>>
>> Also, the amount of water used will have an effect on the strength - as 
>> will the water content of the sand. Too much water = a weak mix of 
>> concrete
>>
>> Tanner-'op
>>
> 
> Butting in here, as I too find the ratios in practice a bit hit and miss, 
> and have to fight a strong tendency to add a bit more cement 'just to make 
> sure':
> 
> Other comments seem to be hitting on about 5:1 sand to cement for mortar, 
> but your ratio for concrete is essentially that same 'spoonful' of cement 
> now extended to cover 7 'spoonfuls' of other stuff.  Is that really reliably 
> enough?
>  (before I resume trying to remake a large number of steps in the - very 
> steep - garden, that are taking me a long time because of the surprisingly 
> large quantities of materials involved...  I would not want to sit back and 
> watch them all get gradually washed away afterwards!)
> 

I always want to add a bit. Doesn't seem feasible it will set sound with 
standard ratios.

Isn't it very largely the surface area of the 'other stuff' together 
with how the packing works? That is, the cement fills holes betwen sand 
particles; the sand/cement fills holes between the aggregate particles. 
And there is just enough 'binding' power in the cement for the huge area 
of sand surface plus the much smaller area of aggregate surface.

Posting in the hope that someone will tell me where I am wrong - if I 
am. That is just how I seem to have absorbed infromation over the years.

The experiemnt I have always wanted to do is to mix in a load of jelly 
(whether real jelly, carragheenan, agar or something similar). Seems to 
me that you might manage a very weak mixture but surprisingly strong 
final substance as the gelling could stop the cement particles flowing 
out. Or maybe it would work to allow very sloppy mixtures to set?

-- 
Rod

Hypothyroidism is a seriously debilitating condition with an insidious 
onset.
Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

On 15 Jul, 11:20, "Spamlet" <spam...@invalid.invalid> wrote:
> "Tanner-'op" <tannerop@i......nvalid.com> wrote in message
>
> news:6e1r7fF4uvloU1@mid.individual.net...
>
>
>
> > Rich wrote:
> >> "RW"  wrote in message
> >>news:6e1ptiF4um4iU1@mid.individual.net...
>
> >>> "Rich"  wrote in message
> >>>news:6e1phgF4u3ctU1@mid.individual.net...
> >>>> Well, I thought 3 parts sand and 1 part cement would be okay, but
> >>>> no. It's too sandy by far. I'm sure I put in 3 levels of cement and
> >>>> 9 of sand.
>
> >>>> I had to crush some of the portland cement because it's a bit old
> >>>> and some of has gone hard, but not rock hard. I used a rolling pin.
>
> >>>> I'm having to chisel out the concrete now and make up a new mix. I
> >>>> notice that when I'm chiseling the concrete out that I made, it easy
> >>>> turns to powder. My house has concrete/pebble walls and I must
> >>>> chisel out and plug with concrete for shelving.
>
> >>>> I'm miffed and not slightly confused why the mix I made turned out
> >>>> so poor. Next time I'll use 2 sand, 1 cement.
>
> >>> Use NEW cement FFS!
>
> >> Does cement "go off?
>
> > Yes
>
> >> I mean, I can crush these clumped up bits to powder, because they are
> >> fairly soft. But is the cement now practically useless even when
> >> ground down?
>
> > Yes.
>
> > Now. what were you doing with a 1:3 mix of cement and sand?
>
> > As this is not classed as a concrete mix but a mortar.
>
> > A concrete mix would be 1:3:4.
>
> > I.E. 1 part cement, 3 parts sand and 4 parts chippings - of varying grades
> > dependant upon the job in hand.
>
> > Also, the amount of water used will have an effect on the strength - as
> > will the water content of the sand. Too much water = a weak mix of
> > concrete
>
> > Tanner-'op
>
> Butting in here, as I too find the ratios in practice a bit hit and miss,
> and have to fight a strong tendency to add a bit more cement 'just to make
> sure':
>
> Other comments seem to be hitting on about 5:1 sand to cement for mortar,
> but your ratio for concrete is essentially that same 'spoonful' of cement
> now extended to cover 7 'spoonfuls' of other stuff.  Is that really reliably
> enough?
>  (before I resume trying to remake a large number of steps in the - very
> steep - garden, that are taking me a long time because of the surprisingly
> large quantities of materials involved...  I would not want to sit back and
> watch them all get gradually washed away afterwards!)
>
> Cheers,
> S

I think the ballast in concrete (e.g. stones) is large enough simply
to take up volume in the mix. But a general strong concrete mix is
1-2-4, so the cement to sand ratio is 1 to 2, more than you would use
for a mortar where 1-3 would be the max (with engineering bricks).
When I was using all-in ballast (sand and stones), I thought the
equivalent to 1-2-4 is now 1-6 which sounded quite weak, but it set
very solid, since the stones are really just bulking up the volume, as
well as stopping cracks propogating etc.
Simon.

"sm_jamieson"  wrote in message 
news:26882ca9-84e3-498d-8175-865f6d434448@m36g2000hse.googlegroups.com...
> On 15 Jul, 11:20, "Spamlet" <spam...@invalid.invalid> wrote:
>> "Tanner-'op" <tannerop@i......nvalid.com> wrote in message
>>
>> news:6e1r7fF4uvloU1@mid.individual.net...
>>
>>
>>
>> > Rich wrote:
>> >> "RW"  wrote in message
>> >>news:6e1ptiF4um4iU1@mid.individual.net...
>>
>> >>> "Rich"  wrote in message
>> >>>news:6e1phgF4u3ctU1@mid.individual.net...
>> >>>> Well, I thought 3 parts sand and 1 part cement would be okay, but
>> >>>> no. It's too sandy by far. I'm sure I put in 3 levels of cement and
>> >>>> 9 of sand.
>>
>> >>>> I had to crush some of the portland cement because it's a bit old
>> >>>> and some of has gone hard, but not rock hard. I used a rolling pin.
>>
>> >>>> I'm having to chisel out the concrete now and make up a new mix. I
>> >>>> notice that when I'm chiseling the concrete out that I made, it easy
>> >>>> turns to powder. My house has concrete/pebble walls and I must
>> >>>> chisel out and plug with concrete for shelving.
>>
>> >>>> I'm miffed and not slightly confused why the mix I made turned out
>> >>>> so poor. Next time I'll use 2 sand, 1 cement.
>>
>> >>> Use NEW cement FFS!
>>
>> >> Does cement "go off?
>>
>> > Yes
>>
>> >> I mean, I can crush these clumped up bits to powder, because they are
>> >> fairly soft. But is the cement now practically useless even when
>> >> ground down?
>>
>> > Yes.
>>
>> > Now. what were you doing with a 1:3 mix of cement and sand?
>>
>> > As this is not classed as a concrete mix but a mortar.
>>
>> > A concrete mix would be 1:3:4.
>>
>> > I.E. 1 part cement, 3 parts sand and 4 parts chippings - of varying 
>> > grades
>> > dependant upon the job in hand.
>>
>> > Also, the amount of water used will have an effect on the strength - as
>> > will the water content of the sand. Too much water = a weak mix of
>> > concrete
>>
>> > Tanner-'op
>>
>> Butting in here, as I too find the ratios in practice a bit hit and miss,
>> and have to fight a strong tendency to add a bit more cement 'just to 
>> make
>> sure':
>>
>> Other comments seem to be hitting on about 5:1 sand to cement for mortar,
>> but your ratio for concrete is essentially that same 'spoonful' of cement
>> now extended to cover 7 'spoonfuls' of other stuff.  Is that really 
>> reliably
>> enough?
>>  (before I resume trying to remake a large number of steps in the - very
>> steep - garden, that are taking me a long time because of the 
>> surprisingly
>> large quantities of materials involved...  I would not want to sit back 
>> and
>> watch them all get gradually washed away afterwards!)
>>
>> Cheers,
>> S
>
> I think the ballast in concrete (e.g. stones) is large enough simply
> to take up volume in the mix. But a general strong concrete mix is
> 1-2-4, so the cement to sand ratio is 1 to 2, more than you would use
> for a mortar where 1-3 would be the max (with engineering bricks).
> When I was using all-in ballast (sand and stones), I thought the
> equivalent to 1-2-4 is now 1-6 which sounded quite weak, but it set
> very solid, since the stones are really just bulking up the volume, as
> well as stopping cracks propogating etc.
> Simon.

Beginning to see light dawning here.  So really we might see the thing as 
the ballast being equivalent to a number of very small bricks, mortared 
together by the sand and cement.

Suppose one just has to watch out for any more absorbent or soluble 'stones' 
that might creep in (bits of old plaster board come to mind, as I consider 
the bags of rubble from our bathroom conversion, as possible ballast 
material for my steps - duly sieved of course.).

All very interesting,

Cheers,
S

Dave Plowman (News) wrote:

>> but too strong! Please explain.
> 
> For example. If you use too strong a mix when bricklaying any movement
> will cause the bricks to crack.

Also strong mixes shrink more when curing.  Using the weakest suitable 
mix helps avoid shrinkage problems and saves money.

-- 
Andy

Spamlet wrote:
> Beginning to see light dawning here.  So really we might see the
> thing as the ballast being equivalent to a number of very small
> bricks, mortared together by the sand and cement.
>
> Suppose one just has to watch out for any more absorbent or soluble
> 'stones' that might creep in (bits of old plaster board come to mind,
> as I consider the bags of rubble from our bathroom conversion, as
> possible ballast material for my steps - duly sieved of course.).
>
> All very interesting,
>
> Cheers,
> S

Don't use secondhand rubble to mix concrete...like anything else, it's only 
as strong as it's weakest link, and if that link is lumps of lime plaster 
and bits of plasterboard, then it's going to diseappear fairly quickly - 
frost is the main enemy of concrete, and given that these highly absorbent 
particles will soak up water like a sponge, the frost will then expand 
these, effectively blasting apart the concrete until it comes away in thin 
sheets.
Limestone, other solid stone chippings or pebbles are the only decent 
quality ballast that should be used with sand and cement for high quality 
concrete.

"Phil L"  wrote in message 
news:2_0fk.27189$E41.25524@text.news.virginmedia.com...
> Spamlet wrote:
>> Beginning to see light dawning here.  So really we might see the
>> thing as the ballast being equivalent to a number of very small
>> bricks, mortared together by the sand and cement.
>>
>> Suppose one just has to watch out for any more absorbent or soluble
>> 'stones' that might creep in (bits of old plaster board come to mind,
>> as I consider the bags of rubble from our bathroom conversion, as
>> possible ballast material for my steps - duly sieved of course.).
>>
>> All very interesting,
>>
>> Cheers,
>> S
>
> Don't use secondhand rubble to mix concrete...like anything else, it's 
> only as strong as it's weakest link, and if that link is lumps of lime 
> plaster and bits of plasterboard, then it's going to diseappear fairly 
> quickly - frost is the main enemy of concrete, and given that these highly 
> absorbent particles will soak up water like a sponge, the frost will then 
> expand these, effectively blasting apart the concrete until it comes away 
> in thin sheets.
> Limestone, other solid stone chippings or pebbles are the only decent 
> quality ballast that should be used with sand and cement for high quality 
> concrete.
Are the plastery bits any use for anything?
Hmm, lots of blackboard 'chalk'...

Could go on the allotment I suppose, but that is real chalk already.

S

Spamlet wrote:
> "Phil L"  wrote in message 
> news:2_0fk.27189$E41.25524@text.news.virginmedia.com...
>> Spamlet wrote:
>>> Beginning to see light dawning here.  So really we might see the
>>> thing as the ballast being equivalent to a number of very small
>>> bricks, mortared together by the sand and cement.
>>>
>>> Suppose one just has to watch out for any more absorbent or soluble
>>> 'stones' that might creep in (bits of old plaster board come to mind,
>>> as I consider the bags of rubble from our bathroom conversion, as
>>> possible ballast material for my steps - duly sieved of course.).
>>>
>>> All very interesting,
>>>
>>> Cheers,
>>> S
>> Don't use secondhand rubble to mix concrete...like anything else, it's 
>> only as strong as it's weakest link, and if that link is lumps of lime 
>> plaster and bits of plasterboard, then it's going to diseappear fairly 
>> quickly - frost is the main enemy of concrete, and given that these highly 
>> absorbent particles will soak up water like a sponge, the frost will then 
>> expand these, effectively blasting apart the concrete until it comes away 
>> in thin sheets.
>> Limestone, other solid stone chippings or pebbles are the only decent 
>> quality ballast that should be used with sand and cement for high quality 
>> concrete.
> Are the plastery bits any use for anything?
> Hmm, lots of blackboard 'chalk'...
> 
> Could go on the allotment I suppose, but that is real chalk already.
> 
> 
I have read that it (gypsum) helps to make clay soil workable.

-- 
Rod

Hypothyroidism is a seriously debilitating condition with an insidious 
onset.
Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

In article ,
	Rod  writes:
> I have read that it (gypsum) helps to make clay soil workable.

I've chucked loads of gypsum slop-ends over the lawn and the
beds, and things that grow there seem to like it. Did the same
with cement in one particular flower bed, and it developed quite
a strong crust. The bluebells all managed to break through it
though, giving their usual dense display of blue.

I wouldn't use these anywhere where you might grow veg though;
there are some nasty things in cement. Probably wasn't a good
idea to dump cement mortar slops into the flower bed in the
first place.

-- 
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Rod wrote:
> Spamlet wrote:
>> "Phil L"  wrote in message 
>> news:2_0fk.27189$E41.25524@text.news.virginmedia.com...
>>> Spamlet wrote:
>>>> Beginning to see light dawning here.  So really we might see the
>>>> thing as the ballast being equivalent to a number of very small
>>>> bricks, mortared together by the sand and cement.
>>>>
>>>> Suppose one just has to watch out for any more absorbent or soluble
>>>> 'stones' that might creep in (bits of old plaster board come to mind,
>>>> as I consider the bags of rubble from our bathroom conversion, as
>>>> possible ballast material for my steps - duly sieved of course.).
>>>>
>>>> All very interesting,
>>>>
>>>> Cheers,
>>>> S
>>> Don't use secondhand rubble to mix concrete...like anything else, 
>>> it's only as strong as it's weakest link, and if that link is lumps 
>>> of lime plaster and bits of plasterboard, then it's going to 
>>> diseappear fairly quickly - frost is the main enemy of concrete, and 
>>> given that these highly absorbent particles will soak up water like a 
>>> sponge, the frost will then expand these, effectively blasting apart 
>>> the concrete until it comes away in thin sheets.
>>> Limestone, other solid stone chippings or pebbles are the only decent 
>>> quality ballast that should be used with sand and cement for high 
>>> quality concrete.
>> Are the plastery bits any use for anything?
>> Hmm, lots of blackboard 'chalk'...
>>
>> Could go on the allotment I suppose, but that is real chalk already.
>>
>>
> I have read that it (gypsum) helps to make clay soil workable.
> 

Alkaline though.
You could always use New Improved B&Q Soil Improver (aka sharp sand!)

Dave Plowman (News) wrote:
> 
> You have your answer. Cement goes off with age - and is so cheap it's not
> worth keeping.
> 

Crushed dead cement is still good for oil spills on the garage floor.

Andy

Spamlet wrote:

> 
> Beginning to see light dawning here.  So really we might see the thing as 
> the ballast being equivalent to a number of very small bricks, mortared 
> together by the sand and cement.
> 

Yes. Concrete is strong in compresssion, relatively weak in shear, and 
very weak in tension.


Essentially conctrete is packed stones. To increase shear strength we 
add sand to stop them sliding about and we add cement to stop the sand 
grains sliding about. We then add steel to give tensile strength.

The cement merely increase the shear strength by adding a reasonably 
high shear matrix between the sand grains.

> Suppose one just has to watch out for any more absorbent or soluble 'stones' 
> that might creep in (bits of old plaster board come to mind, as I consider 
> the bags of rubble from our bathroom conversion, as possible ballast 
> material for my steps - duly sieved of course.).
> 

I dont even bother to do that, TBH. large limps of crap embedded in 
mortar work pretty well.


concrete will work at prettty low cement ratios, but it becomes porous, 
liable to frost damage, aand easily damaged by sharp onbjects.


> All very interesting,
> 
> Cheers,
> S 
> 
>

Phil L wrote:
> Spamlet wrote:
>> Beginning to see light dawning here.  So really we might see the
>> thing as the ballast being equivalent to a number of very small
>> bricks, mortared together by the sand and cement.
>>
>> Suppose one just has to watch out for any more absorbent or soluble
>> 'stones' that might creep in (bits of old plaster board come to mind,
>> as I consider the bags of rubble from our bathroom conversion, as
>> possible ballast material for my steps - duly sieved of course.).
>>
>> All very interesting,
>>
>> Cheers,
>> S
> 
> Don't use secondhand rubble to mix concrete...like anything else, it's only 
> as strong as it's weakest link, and if that link is lumps of lime plaster 
> and bits of plasterboard, then it's going to diseappear fairly quickly - 
> frost is the main enemy of concrete, and given that these highly absorbent 
> particles will soak up water like a sponge, the frost will then expand 
> these, effectively blasting apart the concrete until it comes away in thin 
> sheets.
> Limestone, other solid stone chippings or pebbles are the only decent 
> quality ballast that should be used with sand and cement for high quality 
> concrete. 
> 
> 
but most domestic concrete des not need to be high quality.

And limestine is never used in concrtete to my current knowledge: its 
usually flint (silica), or possibly granite.

Limestone is soft and permeable.

In article ,
   The Natural Philosopher <a@b.c> wrote:
> And limestine is never used in concrtete to my current knowledge: its 
> usually flint (silica), or possibly granite.

> Limestone is soft and permeable.

I did wonder about that. I've never seen it in mixed aggregate. Not that
I've knocked up much.

-- 
*Work is for people who don't know how to fish.

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

The Natural Philosopher wrote:
> Phil L wrote:
>> Spamlet wrote:
>>> Beginning to see light dawning here.  So really we might see the
>>> thing as the ballast being equivalent to a number of very small
>>> bricks, mortared together by the sand and cement.
>>>
>>> Suppose one just has to watch out for any more absorbent or soluble
>>> 'stones' that might creep in (bits of old plaster board come to
>>> mind, as I consider the bags of rubble from our bathroom
>>> conversion, as possible ballast material for my steps - duly sieved
>>> of course.). All very interesting,
>>>
>>> Cheers,
>>> S
>>
>> Don't use secondhand rubble to mix concrete...like anything else,
>> it's only as strong as it's weakest link, and if that link is lumps
>> of lime plaster and bits of plasterboard, then it's going to
>> diseappear fairly quickly - frost is the main enemy of concrete, and
>> given that these highly absorbent particles will soak up water like
>> a sponge, the frost will then expand these, effectively blasting
>> apart the concrete until it comes away in thin sheets.
>> Limestone, other solid stone chippings or pebbles are the only decent
>> quality ballast that should be used with sand and cement for high
>> quality concrete.
>>
>>
> but most domestic concrete des not need to be high quality.
>
> And limestine is never used in concrtete to my current knowledge: its
> usually flint (silica), or possibly granite.
>
> Limestone is soft and permeable.

It must depend on where you live in the UK then because around here it's 
almost all limestone, even the readymixed crowd use it, and almost all BM's 
stock it, along with B&Q etc.
Flint is a rarity, except for decorative purposes and granite is used, but 
in the form of 'granno' - IE sharp green grit.

Phil L wrote:

http://www.tarmac.co.uk/QUARRYVILLE/lab/limestone.html

"Rich"  wrote in message 
news:6e1phgF4u3ctU1@mid.individual.net...
> Well, I thought 3 parts sand and 1 part cement would be okay, but no. It's 
> too sandy by far. I'm sure I put in 3 levels of cement and 9 of sand.
>
> I had to crush some of the portland cement because it's a bit old and some 
> of has gone hard, but not rock hard. I used a rolling pin.
>
> I'm having to chisel out the concrete now and make up a new mix. I notice 
> that when I'm chiseling the concrete out that I made, it easy turns to 
> powder. My house has concrete/pebble walls and I must chisel out and plug 
> with concrete for shelving.
>
> I'm miffed and not slightly confused why the mix I made turned out so 
> poor. Next time I'll use 2 sand, 1 cement.

I asked this

<http://groups.google.co.uk/group/uk.d-i-y/browse_thread/thread/1da50ccd1684eae1/04fc5f8af1be37b2?hl=en&lnk=st&q=#04fc5f8af1be37b2>

And my cement was fluffy and did not need to be broken up by a rolling pin.

Adam

ARWadworth wrote:
> 
> "Rich"  wrote in message 
> news:6e1phgF4u3ctU1@mid.individual.net...
>> Well, I thought 3 parts sand and 1 part cement would be okay, but no. 
>> It's too sandy by far. I'm sure I put in 3 levels of cement and 9 of 
>> sand.
>>
>> I had to crush some of the portland cement because it's a bit old and 
>> some of has gone hard, but not rock hard. I used a rolling pin.
>>
>> I'm having to chisel out the concrete now and make up a new mix. I 
>> notice that when I'm chiseling the concrete out that I made, it easy 
>> turns to powder. My house has concrete/pebble walls and I must chisel 
>> out and plug with concrete for shelving.
>>
>> I'm miffed and not slightly confused why the mix I made turned out so 
>> poor. Next time I'll use 2 sand, 1 cement.
> 
> I asked this
> 
> <http://groups.google.co.uk/group/uk.d-i-y/browse_thread/thread/1da50ccd1684eae1/04fc5f8af1be37b2?hl=en&lnk=st&q=#04fc5f8af1be37b2> 
> 
> 
> And my cement was fluffy and did not need to be broken up by a rolling pin.
> 
> Adam

Glad you posted that refresher. I contributed there and said I had used 
some old cement for a fence post. It set. And a few days, maybe a week 
or two, later I realised that I needed to 'adjust' it. Bolster. Lump 
hammer. And by gosh it was tough.

For critical work - fresh, in date, dry. Never even consider anything else.

For probably-strong-enough - slightly old, still looking good, dry can 
be adequate.

What OP of this thread said, he'd need to send it to a cement factory 
for reprocessing to stand a chance.

-- 
Rod

Hypothyroidism is a seriously debilitating condition with an insidious 
onset.
Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

Phil L wrote:
> Phil L wrote:
> 
> http://www.tarmac.co.uk/QUARRYVILLE/lab/limestone.html 
> 
> 
well well well. Round here its never ever used. gravel (flint) only..

The Natural Philosopher <a@b.c> wrote:
>
>And limestine is never used in concrtete to my current knowledge: its 
>usually flint (silica), or possibly granite.


In my experience, limestone and alluvial gravels are by far the two
most frequently used aggregates for concrete.  Flint is something of a
rarity - I don't think I have ever seen a project that used flint for
a concrete aggregate.

Where gravel is available, it tends to be cheaper.  However, away from
south east England, gravel is used less and limestone dominates the
market.  There are some localised areas where granite is quarried in
large quantities for roadstone, and some of it finds its way into
local readymix plants, but granite is always quite expensive because
of the much higher cost of crushing it - it wears out crushers four or
five times faster than limestone does.

Even in south east England, limestone has taken an increasing share of
the market.  That is largely because of the efforts of ARC and Foster
Yeoman, who ship limestone from the Mendip Hills of Somerset
principally into Acton, West London, using their own fleet of trains.

There is nothing inferior about concrete made with limestone.  Many
large bridges, landmark office developments and other major structures
are built with it.  Most of the nuclear reactor pressure vessels in
the UK's nuclear power stations are made of pre-stressed concrete made
with limestone aggregate.   So it is a top quality product.


[This is not in any way a criticism of your postings about concrete in
this thread, which are otherwise factually correct and make an
interesting read - thanks.]



** Posted from http://www.teranews.com **

"Bruce"  wrote in message 
news:ftms74t2im6fuq6lqi6joq8khc77bl8q7e@4ax.com...
> The Natural Philosopher <a@b.c> wrote:
>>
>>And limestine is never used in concrtete to my current knowledge: its
>>usually flint (silica), or possibly granite.
>
>
> In my experience, limestone and alluvial gravels are by far the two
> most frequently used aggregates for concrete.  Flint is something of a
> rarity - I don't think I have ever seen a project that used flint for
> a concrete aggregate.
>
> Where gravel is available, it tends to be cheaper.  However, away from
> south east England, gravel is used less and limestone dominates the
> market.  There are some localised areas where granite is quarried in
> large quantities for roadstone, and some of it finds its way into
> local readymix plants, but granite is always quite expensive because
> of the much higher cost of crushing it - it wears out crushers four or
> five times faster than limestone does.
>
> Even in south east England, limestone has taken an increasing share of
> the market.  That is largely because of the efforts of ARC and Foster
> Yeoman, who ship limestone from the Mendip Hills of Somerset
> principally into Acton, West London, using their own fleet of trains.
>
> There is nothing inferior about concrete made with limestone.  Many
> large bridges, landmark office developments and other major structures
> are built with it.  Most of the nuclear reactor pressure vessels in
> the UK's nuclear power stations are made of pre-stressed concrete made
> with limestone aggregate.   So it is a top quality product.
>
>
> [This is not in any way a criticism of your postings about concrete in
> this thread, which are otherwise factually correct and make an
> interesting read - thanks.]
>
>
>
> ** Posted from http://www.teranews.com **

Er: in the SE, where I come from: 'gravel' generally = small bits of flint + 
the odd oyster and belemnite fossil, as it comes from Chalk-derived clay 
with flints washed and sorted by rivers. [Take a look at a Google Earth of 
Rickmansworth to get an idea of the vast amount that has already been 
removed along most of the river valleys in the region. Quite scary I find.]

S

Bruce wrote:
> The Natural Philosopher <a@b.c> wrote:
>> And limestine is never used in concrtete to my current knowledge: its 
>> usually flint (silica), or possibly granite.
> 
> 
> In my experience, limestone and alluvial gravels are by far the two
> most frequently used aggregates for concrete.  Flint is something of a
> rarity - I don't think I have ever seen a project that used flint for
> a concrete aggregate.
> 

What did you think alluvial gravel WAS if not flint? Small and smashed 
up..but its still flint.



> Where gravel is available, it tends to be cheaper.  However, away from
> south east England, gravel is used less and limestone dominates the
> market.  There are some localised areas where granite is quarried in
> large quantities for roadstone, and some of it finds its way into
> local readymix plants, but granite is always quite expensive because
> of the much higher cost of crushing it - it wears out crushers four or
> five times faster than limestone does.
> 
> Even in south east England, limestone has taken an increasing share of
> the market.  That is largely because of the efforts of ARC and Foster
> Yeoman, who ship limestone from the Mendip Hills of Somerset
> principally into Acton, West London, using their own fleet of trains.
> 
> There is nothing inferior about concrete made with limestone.  Many
> large bridges, landmark office developments and other major structures
> are built with it.  Most of the nuclear reactor pressure vessels in
> the UK's nuclear power stations are made of pre-stressed concrete made
> with limestone aggregate.   So it is a top quality product.
> 
> 
> [This is not in any way a criticism of your postings about concrete in
> this thread, which are otherwise factually correct and make an
> interesting read - thanks.]
> 
> 
> 
> ** Posted from http://www.teranews.com **

"Spamlet" <spamlet@invalid.invalid> wrote:
>
>Er: in the SE, where I come from: 'gravel' generally = small bits of flint + 
>the odd oyster and belemnite fossil, as it comes from Chalk-derived clay 
>with flints washed and sorted by rivers. 


I have lived most of my life in SE England, and worked in the concrete
industry for many years.  The correct term for what you are describing
as "flint" is "crushed gravel".  

Perhaps it is colloquially known as flint, but in geological terms
flint consists of hard inclusions within sedimentary rocks such as
chalk.  If the chalk is eroded, and the flint particles are washed
down rivers, those particles are then termed alluvial gravel - but
this could take hundreds of thousands or millions of years, and the
washing and sorting process significantly changes the shape of the
particles.  Alluvial gravels are very rounded compared to flints.

I'm sorry to be pedantic but the point of the discussion is to
understand which rocks are used for concrete aggregate, and which are
not.  Flint generally isn't, except as an imprecise term for something
rather different, which is correctly called gravel.

** Posted from http://www.teranews.com **

The Natural Philosopher <a@b.c> wrote:

>Bruce wrote:
>> The Natural Philosopher <a@b.c> wrote:
>>> And limestine is never used in concrtete to my current knowledge: its 
>>> usually flint (silica), or possibly granite.
>> 
>> 
>> In my experience, limestone and alluvial gravels are by far the two
>> most frequently used aggregates for concrete.  Flint is something of a
>> rarity - I don't think I have ever seen a project that used flint for
>> a concrete aggregate.
>> 
>
>What did you think alluvial gravel WAS if not flint? Small and smashed 
>up..but its still flint.


No, that's what it was.  An incredible amount of changes are made from
flint being eroded out of chalk to becoming alluvial or sea-dredged
gravel.  Ask a geologist.  My partner is a geologist, and she is
highly amused that people should describe alluvial gravel as "flint".

That's like describing coal or oil as "trees".

** Posted from http://www.teranews.com **

Bruce wrote:
> The Natural Philosopher <a@b.c> wrote:
> 
>> Bruce wrote:
>>> The Natural Philosopher <a@b.c> wrote:
>>>> And limestine is never used in concrtete to my current knowledge: its 
>>>> usually flint (silica), or possibly granite.
>>>
>>> In my experience, limestone and alluvial gravels are by far the two
>>> most frequently used aggregates for concrete.  Flint is something of a
>>> rarity - I don't think I have ever seen a project that used flint for
>>> a concrete aggregate.
>>>
>> What did you think alluvial gravel WAS if not flint? Small and smashed 
>> up..but its still flint.
> 
> 
> No, that's what it was.  An incredible amount of changes are made from
> flint being eroded out of chalk to becoming alluvial or sea-dredged
> gravel.  Ask a geologist.  My partner is a geologist, and she is
> highly amused that people should describe alluvial gravel as "flint".
> 
> That's like describing coal or oil as "trees".
> 
> ** Posted from http://www.teranews.com **

Long ago, I have bought a bag of fine ready mix concrete in which was 
something that looked like flint. Of the order of quarter inch pieces 
and most edges very square and sharp (some very sharp). At the time, I 
assumed some sort of crushed flint. Clearly not alluvial gravel as that 
would have its edges smoothed off at least a bit.

-- 
Rod

Hypothyroidism is a seriously debilitating condition with an insidious 
onset.
Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

Bruce wrote:
> "Spamlet" <spamlet@invalid.invalid> wrote:
>> Er: in the SE, where I come from: 'gravel' generally = small bits of flint + 
>> the odd oyster and belemnite fossil, as it comes from Chalk-derived clay 
>> with flints washed and sorted by rivers. 
> 
> 
> I have lived most of my life in SE England, and worked in the concrete
> industry for many years.  The correct term for what you are describing
> as "flint" is "crushed gravel".  
> 
> Perhaps it is colloquially known as flint, but in geological terms
> flint consists of hard inclusions within sedimentary rocks such as
> chalk.  If the chalk is eroded, and the flint particles are washed
> down rivers, those particles are then termed alluvial gravel - but
> this could take hundreds of thousands or millions of years, and the
> washing and sorting process significantly changes the shape of the
> particles.  Alluvial gravels are very rounded compared to flints.
> 
> I'm sorry to be pedantic but the point of the discussion is to
> understand which rocks are used for concrete aggregate, and which are
> not.  Flint generally isn't, except as an imprecise term for something
> rather different, which is correctly called gravel.
> 
> ** Posted from http://www.teranews.com **

Flint is the name of the material as a mineral type. Gravel or shingle 
is a generic term for sedimentary particles larger than  sand grain size.

Bruce wrote:
> The Natural Philosopher <a@b.c> wrote:
> 
>> Bruce wrote:
>>> The Natural Philosopher <a@b.c> wrote:
>>>> And limestine is never used in concrtete to my current knowledge: its 
>>>> usually flint (silica), or possibly granite.
>>>
>>> In my experience, limestone and alluvial gravels are by far the two
>>> most frequently used aggregates for concrete.  Flint is something of a
>>> rarity - I don't think I have ever seen a project that used flint for
>>> a concrete aggregate.
>>>
>> What did you think alluvial gravel WAS if not flint? Small and smashed 
>> up..but its still flint.
> 
> 
> No, that's what it was.  An incredible amount of changes are made from
> flint being eroded out of chalk to becoming alluvial or sea-dredged
> gravel.  Ask a geologist.  My partner is a geologist, and she is
> highly amused that people should describe alluvial gravel as "flint".
> 
> That's like describing coal or oil as "trees".
> 

Then your partner is being silly. Its only been smashed up, not 
metamorphosed, and in the gravel in my drive there are plenty of intact 
small flints to be seen, the rtest being spmewaht smashed.


I suppose that he/she is equally amused by roadstone being called 
'granite'. since its no longer bloody great lumps of igneous rock, but 
small stome chippings.

Or limestone being called limestone, since its crushed into a fine powder`?



> ** Posted from http://www.teranews.com **

Rod wrote:
> Bruce wrote:
>> The Natural Philosopher <a@b.c> wrote:
>>
>>> Bruce wrote:
>>>> The Natural Philosopher <a@b.c> wrote:
>>>>> And limestine is never used in concrtete to my current knowledge: 
>>>>> its usually flint (silica), or possibly granite.
>>>>
>>>> In my experience, limestone and alluvial gravels are by far the two
>>>> most frequently used aggregates for concrete.  Flint is something of a
>>>> rarity - I don't think I have ever seen a project that used flint for
>>>> a concrete aggregate.
>>>>
>>> What did you think alluvial gravel WAS if not flint? Small and 
>>> smashed up..but its still flint.
>>
>>
>> No, that's what it was.  An incredible amount of changes are made from
>> flint being eroded out of chalk to becoming alluvial or sea-dredged
>> gravel.  Ask a geologist.  My partner is a geologist, and she is
>> highly amused that people should describe alluvial gravel as "flint".
>>
>> That's like describing coal or oil as "trees".
>>
>> ** Posted from http://www.teranews.com **
> 
> Long ago, I have bought a bag of fine ready mix concrete in which was 
> something that looked like flint. Of the order of quarter inch pieces 
> and most edges very square and sharp (some very sharp). At the time, I 
> assumed some sort of crushed flint. Clearly not alluvial gravel as that 
> would have its edges smoothed off at least a bit.
> 

Glaicial

The way it works is that ice carrues racks that smash other rocks in te 
way, and the whole lot got carried darn sarth, at which point global 
warming was just enough to melt the glaciers, and as they melted they 
left behind huge deposits of crushed rock, mainly flint, but  few other 
types as well: the softer rocks like sandstones became more mud like and 
formed the clays. Largely thats is what you buy as sharp sand and 
gravel. Its full of jaggedy bits of smashed stones.

That is although its been deposited by water, unlike sea stuff which 
gets constantly pounded until the edges are knocked off, the vast 
majority of gravels and sharp sands only made one trip in the water, 
before being left where they are found today.

"The Natural Philosopher" <a@b.c> wrote in message 
news:1216282067.12928.0@proxy01.news.clara.net...
> Bruce wrote:
>> The Natural Philosopher <a@b.c> wrote:
>>
>>> Bruce wrote:
>>>> The Natural Philosopher <a@b.c> wrote:
>>>>> And limestine is never used in concrtete to my current knowledge: its 
>>>>> usually flint (silica), or possibly granite.
>>>>
>>>> In my experience, limestone and alluvial gravels are by far the two
>>>> most frequently used aggregates for concrete.  Flint is something of a
>>>> rarity - I don't think I have ever seen a project that used flint for
>>>> a concrete aggregate.
>>>>
>>> What did you think alluvial gravel WAS if not flint? Small and smashed 
>>> up..but its still flint.
>>
>>
>> No, that's what it was.  An incredible amount of changes are made from
>> flint being eroded out of chalk to becoming alluvial or sea-dredged
>> gravel.  Ask a geologist.  My partner is a geologist, and she is
>> highly amused that people should describe alluvial gravel as "flint".
>>
>> That's like describing coal or oil as "trees".
>>
>
> Then your partner is being silly. Its only been smashed up, not 
> metamorphosed, and in the gravel in my drive there are plenty of intact 
> small flints to be seen, the rtest being spmewaht smashed.
>
>
> I suppose that he/she is equally amused by roadstone being called 
> 'granite'. since its no longer bloody great lumps of igneous rock, but 
> small stome chippings.
>
> Or limestone being called limestone, since its crushed into a fine 
> powder`?
>
>
>
>> ** Posted from http://www.teranews.com **

An experiment gainsayers might like to try before getting any more cherty:

In this Wiki entry:
http://en.wikipedia.org/wiki/Flint

Where the picture caption reads:

"Pebble beach made up of flint nodules eroded out of the nearby chalk 
cliffs"

Try editing it to read: "Pebble beach made up of *gravel* eroded out of the 
nearby chalk cliffs."

Let us know how you get on.

Anyhow, all irrelevant to an overall very handy thread.

Cheers,
S
(One time geologist.  Anybody in the market for my old rock samples?  Ah: 
don't tell me: ballast!)

The Natural Philosopher wrote:
> Rod wrote:
>> Bruce wrote:
>>> The Natural Philosopher <a@b.c> wrote:
>>>
>>>> Bruce wrote:
>>>>> The Natural Philosopher <a@b.c> wrote:
>>>>>> And limestine is never used in concrtete to my current knowledge: 
>>>>>> its usually flint (silica), or possibly granite.
>>>>>
>>>>> In my experience, limestone and alluvial gravels are by far the two
>>>>> most frequently used aggregates for concrete.  Flint is something of a
>>>>> rarity - I don't think I have ever seen a project that used flint for
>>>>> a concrete aggregate.
>>>>>
>>>> What did you think alluvial gravel WAS if not flint? Small and 
>>>> smashed up..but its still flint.
>>>
>>>
>>> No, that's what it was.  An incredible amount of changes are made from
>>> flint being eroded out of chalk to becoming alluvial or sea-dredged
>>> gravel.  Ask a geologist.  My partner is a geologist, and she is
>>> highly amused that people should describe alluvial gravel as "flint".
>>>
>>> That's like describing coal or oil as "trees".
>>>
>>> ** Posted from http://www.teranews.com **
>>
>> Long ago, I have bought a bag of fine ready mix concrete in which was 
>> something that looked like flint. Of the order of quarter inch pieces 
>> and most edges very square and sharp (some very sharp). At the time, I 
>> assumed some sort of crushed flint. Clearly not alluvial gravel as 
>> that would have its edges smoothed off at least a bit.
>>
> 
> Glaicial
> 
> The way it works is that ice carrues racks that smash other rocks in te 
> way, and the whole lot got carried darn sarth, at which point global 
> warming was just enough to melt the glaciers, and as they melted they 
> left behind huge deposits of crushed rock, mainly flint, but  few other 
> types as well: the softer rocks like sandstones became more mud like and 
> formed the clays. Largely thats is what you buy as sharp sand and 
> gravel. Its full of jaggedy bits of smashed stones.
> 
> That is although its been deposited by water, unlike sea stuff which 
> gets constantly pounded until the edges are knocked off, the vast 
> majority of gravels and sharp sands only made one trip in the water, 
> before being left where they are found today.
> 

Up to a point.

Alluvium is from running water, n'est pas? I was thinking if it was from 
a glacier it would be moraine. But then I tried looking it up and found 
the word 'till'.

I can't help feeling that most river deposits are somewhat rounded (but 
not, I agree, as rounded as sea stuff). Where the stuff I mentioned was 
truly sharp.

But you are probably right.

-- 
Rod

Hypothyroidism is a seriously debilitating condition with an insidious 
onset.
Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

Rod wrote:
> The Natural Philosopher wrote:
>> Rod wrote:
>>> Bruce wrote:
>>>> The Natural Philosopher <a@b.c> wrote:
>>>>
>>>>> Bruce wrote:
>>>>>> The Natural Philosopher <a@b.c> wrote:
>>>>>>> And limestine is never used in concrtete to my current knowledge: 
>>>>>>> its usually flint (silica), or possibly granite.
>>>>>>
>>>>>> In my experience, limestone and alluvial gravels are by far the two
>>>>>> most frequently used aggregates for concrete.  Flint is something 
>>>>>> of a
>>>>>> rarity - I don't think I have ever seen a project that used flint for
>>>>>> a concrete aggregate.
>>>>>>
>>>>> What did you think alluvial gravel WAS if not flint? Small and 
>>>>> smashed up..but its still flint.
>>>>
>>>>
>>>> No, that's what it was.  An incredible amount of changes are made from
>>>> flint being eroded out of chalk to becoming alluvial or sea-dredged
>>>> gravel.  Ask a geologist.  My partner is a geologist, and she is
>>>> highly amused that people should describe alluvial gravel as "flint".
>>>>
>>>> That's like describing coal or oil as "trees".
>>>>
>>>> ** Posted from http://www.teranews.com **
>>>
>>> Long ago, I have bought a bag of fine ready mix concrete in which was 
>>> something that looked like flint. Of the order of quarter inch pieces 
>>> and most edges very square and sharp (some very sharp). At the time, 
>>> I assumed some sort of crushed flint. Clearly not alluvial gravel as 
>>> that would have its edges smoothed off at least a bit.
>>>
>>
>> Glaicial
>>
>> The way it works is that ice carrues racks that smash other rocks in 
>> te way, and the whole lot got carried darn sarth, at which point 
>> global warming was just enough to melt the glaciers, and as they 
>> melted they left behind huge deposits of crushed rock, mainly flint, 
>> but  few other types as well: the softer rocks like sandstones became 
>> more mud like and formed the clays. Largely thats is what you buy as 
>> sharp sand and gravel. Its full of jaggedy bits of smashed stones.
>>
>> That is although its been deposited by water, unlike sea stuff which 
>> gets constantly pounded until the edges are knocked off, the vast 
>> majority of gravels and sharp sands only made one trip in the water, 
>> before being left where they are found today.
>>
> 
> Up to a point.
> 
> Alluvium is from running water, n'est pas? I was thinking if it was from 
> a glacier it would be moraine. But then I tried looking it up and found 
> the word 'till'.

moraines are made of till.

I live on one.

Clay here, with flint and chalk well down underneath.

Up the road, gravel pit, where they sieve out the sand (very smashed 
flint), and a fair amount of less smashed flint, which is called gravel 
or shingle.

The difference between chert, flint,  and most sand is one of context: 
all are basically silica.

Gravel/shingle/sand is a loose term that really boils down to fragment 
size..however in the building and gardening trade, flint gravel is just 
called 'gravel'. and you tend to get e.g. 'granite shingle' used to 
describe smashed up granite chippings..

although technically 'limestone gravel' exists, its not called that 
here: Its called MOT type I.. ;-)




> 
> I can't help feeling that most river deposits are somewhat rounded (but 
> not, I agree, as rounded as sea stuff). Where the stuff I mentioned was 
> truly sharp.
> 

Really it may or may not be. If you hit e.g. N walees you will find 
scree slopes of very sharp stuff indeed. It only needs a storm to carry 
a bit away in water, and lay it down for it to become a shingle or 
gravel bed.


it takes a lot longer to weather to rounded pebbles or 'soft sand'

> But you are probably right.
>

"The Natural Philosopher" <a@b.c> wrote in message 
news:1216319619.13538.0@proxy00.news.clara.net...
> Rod wrote:
>> The Natural Philosopher wrote:
>>> Rod wrote:
>>>> Bruce wrote:
>>>>> The Natural Philosopher <a@b.c> wrote:
>>>>>
>>>>>> Bruce wrote:
>>>>>>> The Natural Philosopher <a@b.c> wrote:
>>>>>>>> And limestine is never used in concrtete to my current knowledge: 
>>>>>>>> its usually flint (silica), or possibly granite.
>>>>>>>
>>>>>>> In my experience, limestone and alluvial gravels are by far the two
>>>>>>> most frequently used aggregates for concrete.  Flint is something of 
>>>>>>> a
>>>>>>> rarity - I don't think I have ever seen a project that used flint 
>>>>>>> for
>>>>>>> a concrete aggregate.
>>>>>>>
>>>>>> What did you think alluvial gravel WAS if not flint? Small and 
>>>>>> smashed up..but its still flint.
>>>>>
>>>>>
>>>>> No, that's what it was.  An incredible amount of changes are made from
>>>>> flint being eroded out of chalk to becoming alluvial or sea-dredged
>>>>> gravel.  Ask a geologist.  My partner is a geologist, and she is
>>>>> highly amused that people should describe alluvial gravel as "flint".
>>>>>
>>>>> That's like describing coal or oil as "trees".
>>>>>
>>>>> ** Posted from http://www.teranews.com **
>>>>
>>>> Long ago, I have bought a bag of fine ready mix concrete in which was 
>>>> something that looked like flint. Of the order of quarter inch pieces 
>>>> and most edges very square and sharp (some very sharp). At the time, I 
>>>> assumed some sort of crushed flint. Clearly not alluvial gravel as that 
>>>> would have its edges smoothed off at least a bit.
>>>>
>>>
>>> Glaicial
>>>
>>> The way it works is that ice carrues racks that smash other rocks in te 
>>> way, and the whole lot got carried darn sarth, at which point global 
>>> warming was just enough to melt the glaciers, and as they melted they 
>>> left behind huge deposits of crushed rock, mainly flint, but  few other 
>>> types as well: the softer rocks like sandstones became more mud like and 
>>> formed the clays. Largely thats is what you buy as sharp sand and 
>>> gravel. Its full of jaggedy bits of smashed stones.
>>>
>>> That is although its been deposited by water, unlike sea stuff which 
>>> gets constantly pounded until the edges are knocked off, the vast 
>>> majority of gravels and sharp sands only made one trip in the water, 
>>> before being left where they are found today.
>>>
>>
>> Up to a point.
>>
>> Alluvium is from running water, n'est pas? I was thinking if it was from 
>> a glacier it would be moraine. But then I tried looking it up and found 
>> the word 'till'.
>
> moraines are made of till.
>
> I live on one.
>
> Clay here, with flint and chalk well down underneath.
>
> Up the road, gravel pit, where they sieve out the sand (very smashed 
> flint), and a fair amount of less smashed flint, which is called gravel or 
> shingle.
>
> The difference between chert, flint,  and most sand is one of context: all 
> are basically silica.
>
> Gravel/shingle/sand is a loose term that really boils down to fragment 
> size..however in the building and gardening trade, flint gravel is just 
> called 'gravel'. and you tend to get e.g. 'granite shingle' used to 
> describe smashed up granite chippings..
>
> although technically 'limestone gravel' exists, its not called that here: 
> Its called MOT type I.. ;-)
>
>
>
>
>>
>> I can't help feeling that most river deposits are somewhat rounded (but 
>> not, I agree, as rounded as sea stuff). Where the stuff I mentioned was 
>> truly sharp.
>>
>
> Really it may or may not be. If you hit e.g. N walees you will find scree 
> slopes of very sharp stuff indeed. It only needs a storm to carry a bit 
> away in water, and lay it down for it to become a shingle or gravel bed.
>
>
> it takes a lot longer to weather to rounded pebbles or 'soft sand'
>
>> But you are probably right.

How rounded pebbles and grains are, depends on how many times around the 
sedimentary cycle from beach to rock and back again they have endured.  For 
hard materials like silica the time scales involved are almost unimaginable. 
Real experts can look at your sand/gravel deposit and work out exactly where 
it came from and how it got there and just how long ago the individual 
grains were created, and indeed where they to were made.  For a perfect 
natural concrete look at some Hertfordshire 'pudding stone', the individual 
rounded beach pebbles look as if they are separate from the matrix, but the 
whole breaks clean across - that is, if you are strong enough to break it at 
all.  There is some in my garden...

Ah the heady days of Rutley, Read and Watson.

S