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Posted by jason4225@yahoo.com on May 3, 2007, 4:20 pm
>
>
> > > How long after pouring the concrete do I have to wait before coating
> > > it? I've not found a lot of information on this subject, any good
> > > sites or resources that you would recommend?
>
> > Most of the sidewalks in town are 5 to 75 years old and they are still
> > waiting to coat them. I'd wait that long too.
>
> Most of the sidewalks where I live are not that old, and are in very
> poor condition. It rains a lot here, and the rain appears to erode the
> concrete. This is especially noticeable in places where part of the
> concrete is sheltered from the rain. The part that doesn't get rain
> has an almost new appearance. The part that has been rained on looks
> like the cement dissolved, exposing the rocks/pebbles that was mixed
> into it. In some places this is severe - my old driveway was very
> badly eroded. But any cement around here that has been around for a
> while seems to do this.
>
> Maybe I should just dump some oil on it, and let that protect it from
> rain? :-)
Deterioration of the surface is a bit more complex than simple
freeze-thaw-salt exposure. Over-troweling to produce a super-smooth
surface can produce a really inferior surface with very poor
weathering properties, i.e.
http://www.tpub.com/content/construction/14043/css/14043_199.htm
". . .Begin floating immediately after screeding while the concrete is
still plastic and workable. However, do not overwork the concrete
while it is still plastic because you may bring an excess of water and
paste to the surface. This fine material forms a thin, weak
layer that will scale or quickly wear off under use. . ."
I would avoid oil. You want to dissolve the waterproofing agent in
paint thinner. By the time you paid for the oil and thinner, you
would be approaching the cost of a good acrylic-silicone based
waterproofer but self-formulating an inferior product.
Jason
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