Achieving the desired slip resistance
When specifying the slip resistance of polished concrete surfaces, an optimization of appearance and required slip resistance needs to be made. For example, high gloss finishes may not achieve the required slip resistance for some applications. It is therefore important to consider the slip resistance offered by the combination of finish, texture and sealer (if present) so that the slip resistance and finish requirements can be realistically specified and achieved. The advice of a hard-flooring specialist may be sought regarding the appropriate combination of finish, texture and sealer for the slip resistance performance required.
To provide some guidance, numerous case studies have been carried out to determine what effect variations in the finish, texture and sealer have on the slip resistance. The studies highlighted the following specific points, which should be considered when specifying and constructing slip resistant concrete finishes.
- For external pavements, wet pendulum Class W finishes were consistently specified. A honed finish at 80–100 grit with a penetrating sealer applied gave satisfactory slip resistance. Honed finishes and penetrating sealers give consistent results due to the uniform texture provided.
- Concrete finishes that are honed with a finer grit provide lower slip resistance and therefore increased risk of slipping when the floor is wet.
- Honed finishes generally provide satisfactory results in accordance with the recommendations in HB 197, but may be rendered inadequate by the application of a surface coating.
- Unsealed surface. The case studies revealed BPN s typically greater than 54 where appropriately honed surfaces remained unsealed. However, increased wear over time and resultant polishing of the surface, or loss of texture-providing aggregates should be considered.
- Surface coatings or other products that form a film on the surface generally give unsatisfactory results.
- For large areas, the sealer should be applied to a sample spot and slip resistance tested prior to the application of the sealer to the entire area. This is especially true for coating type sealers as they generally provide much lower slip resistance.
- Penetrating sealers provide better results than those that form a coating or film on the surface. They also assist in maintaining slip resistance by maintaining the surface roughness.
- Rougher textures generally provide higher slip resistance results, but may be harder to clean.
- Uniform application of sealer is important as this will give consistent slip resistance results over the surface. Note that variable slip resistance is considered to be a hazard.
- Applied coating with aggregate broadcast into the coating must have the aggregate distributed uniformly to avoid variable slip resistance.
- Surface wear may decrease slip resistance by either polishing the surface or removing texture-providing aggregate from the surface. Basic concrete quality issues must therefore be addressed to ensure durability of the surface
- Polished surfaces used in foyer areas should have matting at all entries to try and remove water and dirt walked in by the public. Spot cleanup with clean mops or cloths should also be undertaken as required.
- Use of colour pigments in the concrete does not affect the slip resistance.
- Broom finishes provide greater slip resistance across the grain than along it. This finish should therefore be provided normal to the direction of pedestrian movement if possible.
- Stamped and broom finishes give similar slip resistance results as only the micro-roughness of the surface contributes to slip resistance.
- Abrasive blasted finishes can provide variable results due to uneven removal of surface mortar. They are generally suitable only for external use due to the aggressiveness of the finished surface and difficulty in maintaining these types of finishes internally.
- Finishes must suit the application. Rough finishes should be used only where constant contamination with water or other liquids/solids is present.
- Ramps may require increased roughness.
Article courtesy of Cement Concrete & Aggregates Australia website - www.ccaa.com.au