Selected Answers

From Candice Monroe of PROSOCO Inc on February 19, 2014:
Dusting is caused by disintegration of the surface ...read more Dusting is caused by disintegration of the surface of cured/hardened concrete. The loosely bound materials in the surface wear from use - walking, traffic, etc - and break down. It is also called chalking. To prevent dusting,  keep water content as low as possible; do not perform surface finishing with water present on the surface; do not sprinkle dry cement on the surface or trowel it into the surface of plastic concrete. After concrete has set, the application of a densifier/hardener can help prevent dusting in the future.

From Alex Sandilands of Akzo Nobel on February 18, 2014:
Dusting is the formation of powder at the surface. ...read more Dusting is the formation of powder at the surface. When concrete is finished by float or power float techniques, this brings 'bleed' (excess) water to the surface, bringing a higher ratio of cement and fines to the top portion. Dusting can be exacerbated when RH is high and moisture condenses on the surface. To prevent dusting, i use floor hardeners. On an existing floor, thin-film sealer coatings, 'dust sealers,' can be very effective.