How to make VERY strong mortar?

[tonyjeffs]

Part of our 1930's house is made in heavy red engineering brick which
is itself very strong.
The motar is even stronger - It is not easy to remove a section of
brickwork without damaging the bricks. Neighbours have reported the
same.

My 1:3 morter is nothing like as tough. I was wondering - how did they
make such strong mortar?

Tony

[Dave Baker]

"tonyjeffs" <tonyj...@googlemail.com> wrote in message
news:7f9a9d20-f4a1-4e64...@i76g2000hsf.googlegroups.com...

Probably by using sharp sand instead of building sand. That turns a mortar
mix into something akin to concrete which will set rock hard and stick to
bricks like that stuff to a blanket. It's far too inflexible for bricklaying
though. It may well have been a mistake by the original builders.
--
Dave Baker

[Bob Martin]

Could it have been repointed? Just had a guy at the door asking if I wanted my
chimneys repointing as they were doing the house next door. We had noticed
- everything is covered in dust from the machine they use to rout out the old stuff.

[Andrew Gabriel]

In article <g8ohqj$lig$1...@news.datemas.de>,

"Dave Baker" <Nu...@null.com> writes:
>
> "tonyjeffs" <tonyj...@googlemail.com> wrote in message
> news:7f9a9d20-f4a1-4e64...@i76g2000hsf.googlegroups.com...
>> Part of our 1930's house is made in heavy red engineering brick which
>> is itself very strong.
>> The motar is even stronger - It is not easy to remove a section of
>> brickwork without damaging the bricks. Neighbours have reported the
>> same.
>>
>> My 1:3 morter is nothing like as tough. I was wondering - how did they
>> make such strong mortar?
>

> Probably by using sharp sand instead of building sand. That turns a mortar
> mix into something akin to concrete which will set rock hard and stick to
> bricks like that stuff to a blanket. It's far too inflexible for bricklaying
> though. It may well have been a mistake by the original builders.

Also, have you left your mortar for long enough?
It takes something like 6 weeks to reach final set.
However, I would also suspect it's a mistake unless
it was intended to be frequently submerged.

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

[Colin Wilson]

> Could it have been repointed? Just had a guy at the door asking if I wanted my
> chimneys repointing as they were doing the house next door. We had noticed
> - everything is covered in dust from the machine they use to rout out the old stuff.

I hope you asked him for money to get your car washed and the carpets
cleaned then !

[tonyjeffs]

> It may well have been a mistake by the original builders.
> --
> Dave Baker

That makes sense - only some of the brickwork has such strong mortar.
Maybe the wrong batch was delivered.
Tony

[The Natural Philosopher]

Oh? Wish you had told nme that before I built a whole garden wall with it..

Didn't seem hard to me. I always like to use sharp sand.

1:2 mortar is about as hard as it gets tho. After that the cement has
preetty much filled all the gaps between the sand..

[whisky-dave]

"The Natural Philosopher" <a@b.c> wrote in message
news:121961233...@proxy02.news.clara.net...

>
> 1:2 mortar is about as hard as it gets tho. After that the cement has
> preetty much filled all the gaps between the sand..

I did add some PVA glue (about 250ml in a standard bucket) when I was
doing some plastering, and that made it a lot more difficult to sand down
after it had set.

Would it have any effect with mortar and would there be any good or bad
results.

[Andrew Gabriel]

In article <g93tu8$lur$1@qmul>,

"whisky-dave" <whisk...@final.front.ear> writes:
>
> "The Natural Philosopher" <a@b.c> wrote in message
> news:121961233...@proxy02.news.clara.net...
>
>>
>> 1:2 mortar is about as hard as it gets tho. After that the cement has
>> preetty much filled all the gaps between the sand..
>
> I did add some PVA glue (about 250ml in a standard bucket) when I was
> doing some plastering,

Why?
I've done this to make up a small ammount of bonding coat when I
only had finish coat, but it's not a normal thing to do.
I certainly wouldn't put it in the real finish coat.

> and that made it a lot more difficult to sand down after it had set.
>
> Would it have any effect with mortar and would there be any good or bad
> results.

It is used in mortar sometimes, but 250ml sounds like way too much.
1-2 teaspoon fulls per shovel of sand would be about right.
It improves the tensile strength, but even so, you should build
such that you are expecting any tensile strength.
If this is for outdoor use, use Exterior PVA (which is EVA), which
also makes the mortar more waterproof. (PVA isn't waterproof.)

[whisky-dave]

"Andrew Gabriel" <and...@cucumber.demon.co.uk> wrote in message
news:48b5af3b$0$628$5a6a...@news.aaisp.net.uk...

> In article <g93tu8$lur$1@qmul>,
> "whisky-dave" <whisk...@final.front.ear> writes:
>>
>> "The Natural Philosopher" <a@b.c> wrote in message
>> news:121961233...@proxy02.news.clara.net...
>>
>>>
>>> 1:2 mortar is about as hard as it gets tho. After that the cement has
>>> preetty much filled all the gaps between the sand..
>>
>> I did add some PVA glue (about 250ml in a standard bucket) when I was
>> doing some plastering,
>
> Why?

I'd heard that adding PVA to the mix help adhesion and as it was my
first attempt at plastering thought I'd give it a try.
As I was stiring it in I tropped the cup full in the mixing bucket.
It mae it a bot more difficult tom smooth off as the plaster stuck more
readily
to teh trowl and as I said it made sanding down to a flush finish so much
more difficult.
So I eneded up thinking that if I needed a really strong and difficult to
sand finish
in the future all I need to do is add PVA.

> I've done this to make up a small ammount of bonding coat when I
> only had finish coat, but it's not a normal thing to do.
> I certainly wouldn't put it in the real finish coat.

I was using one coat plaster at the time.
It also made the coat whiter.

>
>> and that made it a lot more difficult to sand down after it had set.
>>
>> Would it have any effect with mortar and would there be any good or bad
>> results.
>
> It is used in mortar sometimes, but 250ml sounds like way too much.
> 1-2 teaspoon fulls per shovel of sand would be about right.
> It improves the tensile strength, but even so, you should build
> such that you are expecting any tensile strength.
> If this is for outdoor use, use Exterior PVA (which is EVA), which
> also makes the mortar more waterproof. (PVA isn't waterproof.)

cheers for that info it'll be useful when I patch up the front step :)

[Plaster]

On Aug 28, 9:04 am, "whisky-dave" <whisky-d...@final.front.ear> wrote:
> "Andrew Gabriel" <and...@cucumber.demon.co.uk> wrote in message
>
> news:48b5af3b$0$628$5a6a...@news.aaisp.net.uk...> In article <g93tu8$lur$1@qmul>,

> > "whisky-dave" <whisky-d...@final.front.ear> writes:
>
> >> "The Natural Philosopher" <a...@b.c> wrote in message

> >>news:121961233...@proxy02.news.clara.net...
>
> >>> 1:2 mortar is about as hard as it gets tho. After that the cement has
> >>> preetty much filled all the gaps between the sand..
>
> >> I did add some PVA glue (about 250ml in a standard bucket) when I was
> >> doing someplastering,
>
> > Why?
>
> I'd heard that adding PVA to the mix help adhesion and as it was my

> first attempt atplasteringthought I'd give it a try.

> As I was stiring it in I tropped the cup full in the mixing bucket.
> It mae it a bot more difficult tom smooth off as the plaster stuck more
> readily
> to teh trowl and as I said it made sanding down to a flush finish so much
> more difficult.
> So I eneded up thinking that if I needed a really strong and difficult to
> sand finish
> in the future all I need to do is add PVA.
>
> > I've done this to make up a small ammount of bonding coat when I
> > only had finish coat, but it's not a normal thing to do.
> > I certainly wouldn't put it in the real finish coat.
>
> I was using one coat plaster at the time.
> It also made the coat whiter.
>
>
>
> >> and that made it a lot more difficult to sand down after it had set.
>
> >> Would it have any effect with mortar and would there be any good or bad
> >> results.
>
> > It is used in mortar sometimes, but 250ml sounds like way too much.
> > 1-2 teaspoon fulls per shovel of sand would be about right.
> > It improves the tensile strength, but even so, you should build
> > such that you are expecting any tensile strength.
> > If this is for outdoor use, use Exterior PVA (which is EVA), which
> > also makes the mortar more waterproof. (PVA isn't waterproof.)
>
> cheers for that info it'll be useful when I patch up the front step :)

You can visit http://aplaster.com and get more information on how do
plastering work!
Local Plastering Contractor is on of the best Plastering Company In
Boston MA
I hope to see ya again!

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Plaster <Localpl...@gmail.com>
saying something like:

>You can visit http://aplaster.com and get more information on how do
>plastering work!
>Local Plastering Contractor is on of the best Plastering Company In
>Boston MA
>I hope to see ya again!

"The wood work is generally strong steel, and does not need to be
disturbed."
?

Will you travel to the UK?
--
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
How much more suspenseful can you get?"
- House