[Ged]

have been asked today to pressure wash tarmac drive with mortar stains and snots left by builder. am considering fsc plus brick acid.  told customer i thought it is unlikly to be successful as mortar is harder than the tarmac, the tarmac is in good nick and the mortar staining is 2 weeks old but will do test area first. not tried acid on tarmac before. any advice welcome

ta

ged

[Jake]

Ged

Soak the tarmac first, you should then be able to loosen the worse of the mortar with, say, a paint scraper(carefully), then apply brick acid to dissolve whats left, then wash off

[BDCS]

You can leave the acid on tarmac as long as you want it won't touch it, I did one like this recently - the building was 5 floors high and the render had been dropped all over the new tarmac below. Well soak the snotters with acid then use the turbo nozzle when the acid stops foaming. Even B& Q brick acid works

[Ged]

thanks guys
job done
good result

ged

[Edna Doswell]

I tried phosphoric acid.  A mild wash did not remove concrete from tarmac so used half acid and half water.  Cement still there but tarmac ruined.

[Kev Martin]

I tried phosphoric acid.  A mild wash did not remove concrete from tarmac so used half acid and half water.  Cement still there but tarmac ruined.

PhosphoricAcid does remove it but you have to look at how thick it is???  Imagine the cement / mortar is layers of cling film.  So if it is an inch thick the Phosphoric only takes a film off as thick as cling film.  Now you need to apply it again.  By using stronger acids it just takes more layers off but a lot less controllable