Identifying mortar

[garyo]

Hi,

I want to match my existing brickwork to the new mortar. To me it looks like sharp sand has been used. I'm wondering if there's lime in there too? The white patch in the middle of the photo is where I've rubbed it with my finger to crumble away the top 1mm of weathered in mortar.

I took the photo with my phone, and didn't realise how poor it'd be. I'll get a better photo later on tonight.

Any ideas?

mortar

• garyo
• 10 Mar 2010
• 1

Cheers

Gary

 

[noseall]

It is a typical coarse building sand and lime putty or slaked lime mortar.

You will do well to mach it with a modern equivalent.

I guess a mortar mix with four shovel of yellow building sand with a shovel of sharp and a shovel of hydraulic lime may come close......

Mebbe?

Only trial and error will tell. Don't forget, the mortar still needs to be workable.

 

[stuart45]

garyo,
If you soak a piece of the mortar in acid it will leave you with a sample of the sand. However with lime mortar the type of sand that made workable mortar would not always make workable mortar with cement.
I have matched the colours of lime mortars by using 50% white cement and 50% OPC.
As noseall stated it's a bit of trial and error if you have the time. A bit of black cementone can also help tone down the colour.

 

[garyo]

I've just been chatting to a chap in the yard at the local merchants. He said some people use plasterers sand rather than yellow building sand, and showed me some. They also have some pretty yellow sharp sand there.

What's lime mortar to work with - I don't really want to make it much more difficult for myself to be honest!

Gary

 

[garyo]

Another thread has just mentioned white cement - could I play around with a combination of white cement and sharp sand (or yellow building sand)

Or even a blend of white/grey cement?

Gary

 

[PrenticeBoyofDerry]

If your looking for a lighter colour garyo, I would use white cement and a building sand and lime blend, it can be toned down using OPC.
But again it's trial and error, as the wet mortar will always dry lighter.

 

[garyo]

Okay - I'm going to buy a few bags of sand and various OPC/ WOPC and have a play.

If I was to end up with a blend that largely consisted of sharp sand rather than building sand, is that anything to worry about, apart from it have a slightly grainier consistency?

Thanks

Gary

 

[noseall]

If I was to end up with a blend that largely consisted of sharp sand rather than building sand, is that anything to worry about, apart from it have a slightly grainier consistency?

The granular consistency will not show through no matter what sand you use. Once you have 'struck' the perp's and beds then you will be left with a smooth face no matter what sand you use.

The friable granular appearance will only show through with severe weathering.

 

[stuart45]

If you want the aggregate showing, you will need to rub the joints lightly with a piece of wood, or if you are using lime mortar leave them flush and hit them a few days later with the brush.
This type of jointing is not as weather proof as using metal jointers though. Years ago brick joints were just left flush however.