using lime in cement mix

[marsaday]

i am about to blockup an old window with old bricks. it is a solid wall.

i want to use lime in the mix. what would be the correct ratio if i use cement as well. is it 4 sand i cement and i lime?

could i use lime on its own?

 

[tommyl18]

ratio would be 4:1:1 why do you want to use lime in the mix?? you cant just use lime because it wont set

 

[marsaday]

is that really correct? are you in the trade or are you a diyer. i ask that because lots of folk reckon you can just use lime. isnt that how all the old houses were built. they didnt use cement.

anyone clear this up because i am more confused now?

 

[tommyl18]

well put it like this we did a rendering job and i had a labourer who was a newby and he was mixing a 6:1:1 mix of sand cement and lime and he ran out of cement and and never told us so just added more lime thinking that would be ok and we had to knock the whole lot off and start again because it just crumbled off the wall just hadnt set at all lime helps with workability thats why we use it in render to help spread it up the wall but cement has lime in it any way so u wouldnt need to add any to your mortar

 

[Alastairreid]

is that really correct? are you in the trade or are you a diyer. i ask that because lots of folk reckon you can just use lime. isnt that how all the old houses were built. they didnt use cement.

anyone clear this up because i am more confused now?

lime was used for thousands of yrs before the advent of opc!

http://www.buildingconservation.com/articles/cement/cement.htm

 

[tommyl18]

i stand corrected

 

[stuart45]

For normal bricklaying 6/1/1 is the mix. If you are using a lime/sand, the correct type of lime is needed, which is hydraulic lime. The bags you get from the merchants are non hydraulic lime and shouldn't be used for a lime mortar for bricklaying unless a pozzolan is added.

 

[mointainwalker]

The lime mix I use is 1 hydraulic lime to 3 1/2 sand. A big difference is the time it takes to set - much, much longer.

But that also means you don't have to worry over your luch break about cleaning your tools.

I'm surprised that Tommy reckoned that lime wouldn't set, I thought that lime was re-gaining a little popularity in the UK.

Maybe should add that I use this mix for rendering and laying rough-stone walls, not bricklaying. don't know if that has any significance.

 

[stuart45]

I think Tommy was talking about the hydrated non hydraulic lime you get from the merchants. Non hydraulic lime is normally used inside unless in a cement mortar as it is much slower to harden.

 

[lostinfens]

Glad to see this old chesnut returned
The question of type, eg hydraulic/none hydraulic & mix will rage for ever. The purists however, of which I beleive I'm one,will always hold that a mix of sand/ lime putty with the possible addition of a none cement based pozzolanic was is and always will be the only true lime mortar.
It is in my mind analogous to whether it is organic or none organic, it can't be half organic, that is add cement and it is a cement mortar with lime.
I'm surprised that the use of lime-putty as a basis of lime mortar isn't more appreciated on this forum.
Lime mortar is great to work with, can be "knocked up" instead of being thrown away and contrary to some opinions, sets a treat. Also a reasonable match can be acheived with a bit of work.

 

[tommyl18]

im a plasterer by trade and hence only know the use of lime in render mix and yea it was hydrated lime that i used ive done a bit of brick laying but not a lot but only ever used cement hence my lack of knowledge

 

[lostinfens]

Wasn't having a pop at you Tommy, it's often mentioned that lime mortar doesn't go hard or that it takes it's time. Never had a problem myself, then again never built an entire house out of it. If I did , I may be observed sneaking a drop of cement in, but don't tell anyone (actually thats's not true)

 

[karlosmaximos]

I'd go for 5:1:1,which will probably start a debate on its own
As for lime setting-whn i did my apprenticeship,we used to use lime mortar at college,when you had finished building your project you would knock it down and the mortar would be remixed for use again

 

[lostinfens]

I remember the old re-usable muck at college, had to knock down all your own creation, then cart the muck to the mill & shovel it in for re-use.
I think it was just bagged lime used there though, putty would've been too expensive. It did go off a treat though didn't it?
It was used over & over until the "babys' heads" got too many and a new batch mixed-happy days.
As for the 5:1:1 debate, refer to my earlier post

 

[Nige F]

Interesting post - My son`s F.in Law taught him to spread .In his garage (with a couple of temporary walls for P/B skimming) , and they used lime/sand so he could practice render each day- put on then scraped off Funny thing tho`. When I was @ college, - baby`s head meant something else to us plumbers