Our new concrete deck has a chaulky powder, why?

Question

We had a concrete deck poured 10 days ago. Everyday, twice a day I have to sweep it off due to a chalky powder which get carried into our home. The contractor said to pressure wash it, we did & it didn't help.

Any suggestions?

Answer 1

The pour dried to quickly ? was it very hot when it was poured ? if so and it wasn't kept wet to dry slowly it will get that chalky coating on the top .

If a recently placed concrete slab develops hairline cracks or the surface is dusting, what is the likely cause?

Excessive troweling after the placement and screeding of the concrete will bring excess fines and water to the surface, weakening the surface. Hairline cracks and dusting can result. Over-troweling the surface during finishing can produce the same problems.

Additionally, the rapid of loss of water from the surface of the concrete will cause the slab to cure at an uneven rate. This can happen during periods of high temperature or wind. If the top portion of the slab dries before the lower portion, the concrete will cure at different rates, causing the slab to develop cracks

Answer 2

The first two guys are correct, however, the dusting will never end until you seal the concrete(NO THOMPSONS).  The fact the the water evaporated two quickly means the the weakest part of the concrete is the top layer, so sealing this will help.  Use a good concrete  waterbased sealer(15-30/gal) and this will solve your problems. visit www.ugl.com/drylok/...

Answer 3

Wicket is right, too much water in the mix, and/or over screeding.

The dust problem will eventually go away as the top surface wears down to where it's properly cured.