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RonVT 02-23-2008 12:34 PM

crumbling aggregate
Hi, looking for some advice. I poured an exposed aggregate deck two summers ago and it is crumbling away!! I hand mixed the concrete 3 parts gravel to 1 cement. then washed it with muratic acid and then sealed it with 2 coats of "Day - Chem Cure & Seal 30% (J-23)". After the first winter it was crumbling around the hot tub and one other spot. This year it is getting really bad in the areas exposed to snow & ice. Why did it happen and how might I fix it??
Any suggestions?

mudmixer 02-23-2008 01:51 PM

Is the aggregate actually crumbling or is it just being released from the comcrete?

You may have "burned" the cement matrix around the aggregate with too much acid or did not wash at the right time for the concentration. This can reduce the resistance to freezing & thawing cyles or ever wetting & drying cylces.

I have no idea of what your climate is like, but you obviously have freezing. Around here, you also need air entrained concrete to resist the freezing & thawing cycles. It is required by code for exposed concrete. Because of this the concrete suppliers end up supplying most of the exposed concrete, since they are familiar with the air entraining admixtures.

glennjanie 02-24-2008 07:19 PM

Welcome RonVT:
I noticed you didn't mention any sand in your mix. If that is the case there was not enough cement binding for the agregate.

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