Re-pointing

[Harry Newcastle]

Hi everyone

just after some advice on identifying the mortar used on my house as need to do some re-pointing. Its 1950 semi, with damp course and cavity, so I would expect cement based mortar rather than lime. However, if scraped across surface with a key the grains of sand fall away with little pressure, certainly less than I would expect with cement in the mix, and wondered if the softness may be a lime mortar.
Basically, is there anything obvious I can do to identify if its cement or lime mortar?

Would a sand-rich cement mix cause it to be easily scraped out rather than it being lime?

Is the softness typical of a cement mortar that is now over 60years old?
Help Much appreciated
Harry

 

[Rigsby]

It may simply have been mixed too weak and will have gone through a few freeze-thaws in its time.

The 50's did tend to use sand and lime mixes and may have waived an empty cement bag over it into frightening it into setting. You can therefore either get a sand and lime mix for pointing or use a 6 sand 1 hydrated lime and 1 cement mortar.

For the sand and lime there are a few lime specialist suppliers dotted around the Country or for injection method there is easy point in both versions.

Rake out to 10mm and keep well wetted. If it is a warm time of year keep it damp for a few days to help it cure or cover with Hessian or scaffolders debris netting.

 

[Harry Newcastle]

That's great advice cheers. By too weak does that just mean very little cement (if any) or too much sand?

 

[CTPlastering]

Guessing ur from the toon ? Never seen a second name of newcastle before ? Lol