Beware of efflorescence on colored concrete - it took me 12 hours to fix

I poured a dark gray patio for a client in Phoenix last summer and a week later white crust started showing up. I spent a full Saturday scrubbing with vinegar and a stiff brush, then went back with a mild acid wash. That stuff is stubborn and it ate up an entire weekend I didn't plan for. Anyone else had to deal with this on a colored slab?

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tessa3681mo ago

Did you check if the concrete mix itself had too much calcium chloride in it? I ran into this on a job in Tucson and it turned out the batch was loaded with accelerators to help it set in the heat. That white crust didn't just come from the ground water it was actually baking out of the slab from the inside. Took me three trips to figure out what was going on and I had to seal it with a breathable sealer after to stop it from returning. Might be worth checking your supplier's mix ratios for the hot weather stuff.