I'm making some ornamental blocks to repair a garden wall. They have a
sloping front face with exposed stone chippings.
I have just about got the knack of making them - 1-3-6 mix cement sand
aggregate. Leave them to set overnight, brush and wash gently to
expose stone.

The remaining problem I'm having is the colour. For the original
1930's wall the concrete is a sort of grey-beige colour. My new blocks
are sparkling white, including the ones I made a year ago.

I suppose I could start adding dye, but wondered if the answer is more
in the mix I'm using. Maybe I'm not accurate.

Any thoughts on improving what I'm doing.

Thanks

Tony

Sand colour and cement type both influence the results - but if you
want a yellowish tint go for a mortar dye.

tonyjeffs wrote:

I'm making some ornamental blocks to repair a garden wall. They have a
sloping front face with exposed stone chippings.
I have just about got the knack of making them - 1-3-6 mix cement sand
aggregate. Leave them to set overnight, brush and wash gently to
expose stone.

The remaining problem I'm having is the colour. For the original
1930's wall the concrete is a sort of grey-beige colour. My new blocks
are sparkling white, including the ones I made a year ago.

I suppose I could start adding dye, but wondered if the answer is more
in the mix I'm using. Maybe I'm not accurate.

Any thoughts on improving what I'm doing.


Your choice of sand has the biggest effect on the result. However,
matching a 70-year old concrete block with a newly made concrete block
is almost impossible, because the 1930s blocks will have weathered to
expose some of the aggregate in the original concrete.

Why not try to obtain some matching 1930s blocks from demolition or
possibly an architectural salvage yard?

Otherwise, consider replacing the 1930s blocks with new ones so they
all match.

Here is a pic of my efforts compared to the original.
The latest looks better, but I guessed the sand and it isn't very
strong.
http://lh5.ggpht.com/tonyjeffs2/SEeK...%20blocks.jpg?

tonyjeffs wrote:

Here is a pic of my efforts compared to the original.
The latest looks better, but I guessed the sand and it isn't very
strong.
http://lh5.ggpht.com/tonyjeffs2/SEeK...%20blocks.jpg?

How long after making it are you judging the strength? As I understand
it, concrete-based products can take a long time to fully harden - from
memory 21 days is often used as a guide for ordinary concrete. Make sure
it is does not dry out fully for at least a few days.

The other devil in such products is using the wrong amount of water -
too much or too little. (Funny how they always seem to be wading through
very liquid concrete on the Grand Designs of this world. :-) )

The next devil is thorough mixing. Most of the minor works I DIY at home
have plenty of strength but that is in spite of crap mixing. I know very
well that thoroughness is vital to achieve maximum strength.

Finally, do you do anything to shake the mould? I am thinking that a
good vibration might help. Maybe even poking and/or nudging it with an
SDS chisel?

I am impressed that you are putting in such effort to get it 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

On 5 Jun, 08:45, Rod wrote:
tonyjeffs wrote:


I am impressed that you are putting in such effort to get it right.

....I think a touch of madness explains that one!
The satisfaction is in solving the puzzle rather than fixing the wall.

The tips are all good. I'll take them on board and do a bit of trial
and error.
I'll find some cans so I can gauge my mix more accurately.
Water's tricky - dry mix is strong, but doesn't fill the mould so
easily.

I'm checking the strength after about 24 hours.But I'll leave them
laying around for a day or two after that.
Mixing is good - half size B&Q cement mixer.

For the vibration aspect, I thought maybe I could stand the setting
blocks on top of the washing machine while t Mrs J does the washing,
but she wasn't happy with the idea'.
A vibrating platform would be better'n a chizel as theres a
polysterine spacer in the middle and not much room to prod, but a
chizel will help. Maybe I can rig else up to vibrate it. Maybe a
wooden platform resting on the lawnmower. I'll give it some thought.

Thanks for v helpful ideas.

Tony

tonyjeffs wrote:
I'm making some ornamental blocks to repair a garden wall. They have a
sloping front face with exposed stone chippings.
I have just about got the knack of making them - 1-3-6 mix cement sand
aggregate. Leave them to set overnight, brush and wash gently to
expose stone.

The remaining problem I'm having is the colour. For the original
1930's wall the concrete is a sort of grey-beige colour. My new blocks
are sparkling white, including the ones I made a year ago.

I suppose I could start adding dye, but wondered if the answer is more
in the mix I'm using. Maybe I'm not accurate.

You could try accelerated aging. Soak the cured blocks overnight in a
bucket containing some coffee or teabags, a lump of rusty metal, some plant
fertiliser and a bit of milk or sugar (not intentionally a recipe for
builder's tea-break, just coincidence). You'd get a staining effect, but
you'd also get rapid colonisation by microbes, lichen etc. Just a mad
idea....

tonyjeffs wrote:



Here is a pic of my efforts compared to the original.
The latest looks better, but I guessed the sand and it isn't very
strong.
http://lh5.ggpht.com/tonyjeffs2/SEeK...%20blocks.jpg?


I would use a partial cement replacement with 30% to 50% PFA
(pulverised fuel ash) replacing 30% to 50% of the cement. That will
give a greyer rather than whiter appearance. It will give a slightly
lower strength but a much more durable block.

The darker colour of the 1930s block is partly due to things that are
growing on the surface. I cannot recall what they are called, but I
have successfully encouraged their growth on a new retaining wall that
abutted an older one by painting the new concrete with diluted organic
live yoghurt (unpasteurised). 70% yoghurt, 30% water. If your local
water supply is chlorinated, use mineral water. Spa still mineral
water (in the red capped bottle) is best for this.

Wait for at least 6-8 weeks before you do it.

I think the combination of a greyer block and the live yoghurt should
do the trick. If it doesn't work, I offer a 100% refund of the price
you paid for this advice. Or you can easily scrub it off while hosing
it down. ;-)

And no, none of this is a joke, however funny it might sound. ;-)

On Jun 5, 9:15*am, tonyjeffs wrote:
On 5 Jun, 08:45, Rod wrote:

tonyjeffs wrote:

I am impressed that you are putting in such effort to get it right.

...I think a touch of madness explains that one!
The satisfaction is in solving the puzzle rather than fixing the wall.

The tips are all good. I'll take them on board and do a bit of trial
and error.
I'll find some cans so I can gauge my mix more accurately.
Water's tricky - dry mix is strong, but doesn't fill the mould so
easily.

I'm checking the strength after about 24 hours.But I'll leave them
laying around for a day or two after that.

strength of any concrete mix after 24 hrs is going to be extremely
low. Test them after a sensible time, a few days at a bare minimum.


Mixing is good - half size B&Q cement mixer.

For the vibration aspect, I thought maybe I could stand the setting
blocks on top of the washing machine while t Mrs J does the washing,
but she wasn't happy with the idea'.
A vibrating platform would be better'n a chizel as theres a
polysterine spacer in the middle and not much room to prod, but a
chizel will help. *Maybe I can rig else up *to vibrate it. Maybe a
wooden platform resting on the lawnmower. *I'll give it some thought.

Thanks for v helpful ideas.

Tony

One idea not yet mentioned is to add subsoil, IIRC upto 1/3 as much as
the sand. Needs good mixing though.


NT

On Jun 5, 4:31 pm, Bruce wrote:
tonyjeffs wrote:

Here is a pic of my efforts compared to the original.
The latest looks better, but I guessed the sand and it isn't very
strong.
http://lh5.ggpht.com/tonyjeffs2/SEeK.../cM87p3iqMyM/M...

I would use a partial cement replacement with 30% to 50% PFA
(pulverised fuel ash) replacing 30% to 50% of the cement. That will
give a greyer rather than whiter appearance. It will give a slightly
lower strength but a much more durable block.

The darker colour of the 1930s block is partly due to things that are
growing on the surface. I cannot recall what they are called, but I
have successfully encouraged their growth on a new retaining wall that
abutted an older one by painting the new concrete with diluted organic
live yoghurt (unpasteurised). 70% yoghurt, 30% water. If your local
water supply is chlorinated, use mineral water. Spa still mineral
water (in the red capped bottle) is best for this.

Wait for at least 6-8 weeks before you do it.

I think the combination of a greyer block and the live yoghurt should
do the trick. If it doesn't work, I offer a 100% refund of the price
you paid for this advice. Or you can easily scrub it off while hosing
it down. ;-)

And no, none of this is a joke, however funny it might sound. ;-)

Bull****

Or cow****, diluted and painted on.

MBQ

On 6 Jun, 10:54, "Man at B&Q" wrote:
On Jun 5, 4:31 pm, Bruce wrote:





wrote:

Here is a pic of my efforts compared to the original.
The latest looks better, but I guessed the sand and it isn't very
strong.
http://lh5.ggpht.com/tonyjeffs2/SEeK.../cM87p3iqMyM/M....

I would use a partial cement replacement with 30% to 50% PFA
(pulverised fuel ash) replacing 30% to 50% of the cement. *That will
give a greyer rather than whiter appearance. *It will give a slightly
lower strength but a much more durable block.

The darker colour of the 1930s block is partly due to things that are
growing on the surface. *I cannot recall what they are called, but I
have successfully encouraged their growth on a new retaining wall that
abutted an older one by painting the new concrete with diluted organic
live yoghurt (unpasteurised). *70% yoghurt, 30% water. *If your local
water supply is chlorinated, use mineral water. *Spa still mineral
water (in the red capped bottle) is best for this.

Wait for at least 6-8 weeks before you do it.

I think the combination of a greyer block and the live yoghurt should
do the trick. *If it doesn't work, I offer a 100% refund of the price
you paid for this advice. *Or you can easily scrub it off while hosing
it down. *;-)

And no, none of this is a joke, however funny it might sound. *;-)

Bull****

Or cow****, diluted and painted on.

MBQ- Hide quoted text -

- Show quoted text -

Thanks everyone.
I'll do a few experiments with the accelerated ageing ideas.
I tried just painting wet soil on one. I'll see how that goes.
Yoghurt and butter sounds good too.
No cows in the area though.

It takes a long time to produce each block, - clean up and prepare
the mould is most of the work.
I'd like to produce a cou[;e of hundred, so i need to speed up my
technique.

Tony
"Making blocks in the hot sun
I fought the law and the law won
Today I got another ...six done
I fought the law and the law won.....