mortar on slabs

[billozz]

hi guys similar problem to someone o here a while ago ive laid some slabs and because im not very good at pointing i have some mortar on the slabs, i have tried brick acid and it doesnt seeem to work very well, i am diluting it quite a bit, can i use it neat? i am considering using a wire brush on a drill but not sure if this will scratch he slabs, any ideas please
thanks
Bill

 

[JohnD]

unless the weather was ideally moist that night, dropped mortar will be nowhere near as hard and strong as the precast slabs. Try a broad metal scraper.

 

[billozz]

John,
thanks for the reply, unfortunately the slabs got wet because i made the mistake of trying to wash of the excess with a brush and water, but....the mortar between the slabs wasnt set so its been washed around all over the slabs and now they seem to have a cementy film over them.

 

[r896neo]

you can use brick acid neat but pre wet the slabs.

Of course test it on an off cut or inconspicuos area first.

The best technique is to put it on and to leave it for a few mins, then scrub it hard with a wire brush then leave it for another 5 mins and hose off. Then repeat.

 

[theprinceofdarkness]

Patience, patience, imagine a room full of balls with cement between them, this is what your mortar would like if magnified a million times. Your acid dissolves the cement bit leaving the balls (sand) untouched. the problem is that under the mortar is another surface with different coloured sand.
So the technique is to dissolve the cement then scrub (try a BRASS) brush to remove the top layer of the adhering sand to expose more cement to be dissolve off with some more acid. I would use the acid as it is and apply it with a artists brush to the effected areas, give it 5 minutes, scrub and repeat.
Frank

 

[billozz]

under the mortar is another surface with different coloured sand.

do you mean the slab?