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Posted: Thu Jun 28, 2007 9:07 pm
by bennett
Help please,
Constructed some garden steps using breeze blocks laid black granite slabs using white cement as instructions said and sand 6-1 mix plastered steps up and painted. Now when it rains keep getting white run marks from under slabs which stains paint. Slabs do overhang steps, if i dug groove out under slabs and filled with a filler would this stop problem
Posted: Fri Jun 29, 2007 9:03 am
by Tony McC
Probably not.
What's the source for this white stain? Obviously it's the mortar, based as it is on a white cement, but is it cement or is it efflorescence? If it's cement, that would indicate either poorly mixed mortar or a mortar prepared using a perished cement, and there's no cure other than starting again. If it's eff, then it will disappear over time.
Is the mortar hard? As a 6:1 mix, it should be impossible to push the blade of a screwdriver into the mortar. If it's soft, then the problem's with the mortar rather than with eff.
Posted: Fri Jun 29, 2007 11:51 pm
by bennett
Tony McC wrote:Probably not.
What's the source for this white stain? Obviously it's the mortar, based as it is on a white cement, but is it cement or is it efflorescence? If it's cement, that would indicate either poorly mixed mortar or a mortar prepared using a perished cement, and there's no cure other than starting again. If it's eff, then it will disappear over time.
Is the mortar hard? As a 6:1 mix, it should be impossible to push the blade of a screwdriver into the mortar. If it's soft, then the problem's with the mortar rather than with eff.
The mortar seems quite hard but when scraped out seems wet it only seems to happen when it rains the water seems to be running under the slab and i suppose somehow the cement gets wet and white stains appear on the riser which stains the paint and now started to stain the slabs