Prevent & Repair Concrete Surface Dusting
Dusting is the white chalking and/or powdering of hardened concrete at the surface. There are many reasons for this weakened layer of concrete. It can range from poor mixing of the concrete at the plant, old age, or even insufficient curing at the surface. The most common reason, however, is excess bleed water at the surface during the finishing process.
If there is too much water in the concrete mix, this water will rise to the surface during the finishing process (troweling). This bleed water can carry finer particles and cement to the surface, forming a weak layer of concrete at the upper most top of the slab. This surface laitance is actually a porous layer of softer concrete that slowly breaks down, thus creating the white powdery surface.
Concrete surface dusting can be prevented in both internal and external works by ensuring good curing practices, including the use of MasterKure curing compounds. MasterKure 111 will assist in finishing and reducing evaporation that leads to rapid moisture loss during finishing.
Repairs can be made using MasterTop 333, a deep-penetrating silicate solution which has been developed for sealing and dust-proofing powdery and/or friable concrete and masonry surfaces. MasterTop 333 binds the surface of old or new concrete to reduce dusting and prolongs the serviceable life of problem concrete floors