Bricks, Masonry, Asphalt and Concrete - Cement coating on poured concrete wall
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kybigfish
05-27-07, 03:17 PM
Hi. I need some help and advise. I have a garage with one side having a
3' high poured concrete side. This has been covered with a 3/8" coating
of cement that is falling off. I have been told that I should use a mortar
mix and then rub sand into the surface before it dries. Is this what was
used back in 1946? Can anyone confirm this and give me any hints on
how to do it? I have already removed the loose material and cleaned
the wall area that had been covered. Thanks for your help.
kybigfish
3' high poured concrete side. This has been covered with a 3/8" coating
of cement that is falling off. I have been told that I should use a mortar
mix and then rub sand into the surface before it dries. Is this what was
used back in 1946? Can anyone confirm this and give me any hints on
how to do it? I have already removed the loose material and cleaned
the wall area that had been covered. Thanks for your help.
kybigfish
PYZON
05-28-07, 10:15 AM
My suggestion would be a sand and cement mix (similar to what is usually called "topping" mix if available in your area from Quikrete or Sakrete) rather than mortar. Mortar shrinks much more than cement when curing and is much weaker to boot. If you want the new coating to last and stick well, use a surface bonder like Thorobond (paint it on the old surface before trowling on the new) or a bonding admix like Acryl 60 (that you use in the recipe of the new coating, substituting for some or most of the water).
Both of these products may be tough to find in the do-it-yourself stores, more likely where the masonry professionals shop, like a building supply house and both are made by the folks that make Thoroseal.
Lastly, if using one of the premixed products from Quikrete or Sakrete, buy some plain Portland Cement to add to the mix to make it much stronger than what comes out of the bag, maybe adding 5 lbs or so to each 80 lb bag of premixed topping.
Another thought would be to use premixed stucco finish. (Also from Thoro !) I know I sound like a salesman for Thoro, but their stuff is intended for the professional rather than the amateur and is meant to last.
To duplicate the old sandy texture, wet a tool called a sponge float and "scrub" the surface in a circular pattern which will raise the sand in the mix to the surface and level out the whole area. Let the new coating cure awhile until it's hard to press a thumb more than 1/8" into the surface, maybe an hour or more.
And wear gloves in case you are sensitive to cement alkaline.
Both of these products may be tough to find in the do-it-yourself stores, more likely where the masonry professionals shop, like a building supply house and both are made by the folks that make Thoroseal.
Lastly, if using one of the premixed products from Quikrete or Sakrete, buy some plain Portland Cement to add to the mix to make it much stronger than what comes out of the bag, maybe adding 5 lbs or so to each 80 lb bag of premixed topping.
Another thought would be to use premixed stucco finish. (Also from Thoro !) I know I sound like a salesman for Thoro, but their stuff is intended for the professional rather than the amateur and is meant to last.
To duplicate the old sandy texture, wet a tool called a sponge float and "scrub" the surface in a circular pattern which will raise the sand in the mix to the surface and level out the whole area. Let the new coating cure awhile until it's hard to press a thumb more than 1/8" into the surface, maybe an hour or more.
And wear gloves in case you are sensitive to cement alkaline.
kybigfish
05-28-07, 05:15 PM
Hi Pyzon. Thanks for your reply to my coating problem. I've been doing
alot of cement repairs around here and already have the "topping" mix
that you mentioned. Also the Thorobond bonding agent and the wet float.
I'll give your suggestions a try. One has alot of "cement" problems when
you live on the side of one of the many hills here in Louisville, KY. Again,
many thanks for your help.
kybigfish
alot of cement repairs around here and already have the "topping" mix
that you mentioned. Also the Thorobond bonding agent and the wet float.
I'll give your suggestions a try. One has alot of "cement" problems when
you live on the side of one of the many hills here in Louisville, KY. Again,
many thanks for your help.
kybigfish