A good designed and placed concrete should serve its intended purpose for its entire service life. Several challenges can be encountered after placement of concrete and one of such challenges is Dusting
Dusting is characterized by powdering at the surface of the concrete slab. This powdered surface may weather and expose the aggregate. During placement, bleed water carries cement and finer particles to form a layer of laitance on the slab surface. Several factors contribute to dusting, some of which include:
Excessive bleed water on the surface which can create a porous skin layer
Very rapid drying of the surface from wind/weather may reduce the water available at the surface for cement to hydrate fully, leaving a dusty surface.
Improper curing of slab thereby producing weak surface
The following can be adopted:
To prevent dusting, do not carry out finishing operations with excess water on the surface. Concrete should have finished bleeding before any operation is carried out.
Ensure effective curing, which gives a stronger surface, more resistance to abrasion, etc, by using plastic sheet or hessian cloth.
Control water cement ratio. Use a moderate slump mix of not more than 125mm
Protect slab from weather during concreting and curing
Avoid using polythene sheet when laying slab.
Dusting can be rectified by one of the following:
Grinding off existing weak layer of the concrete thereby exposing the concrete layer with adequate strength.
Application of a concrete densifier, sealer or hardner on concrete surface after inspection of concrete floor
April 30, 2018
OGMT provides complete structural waterproofing and damp proofing solutions for buildings (new and refurbished) and infrastructure..