Question: We recently heard from a residential client about a pool project that was completed several years ago. The concrete deck surrounding the pool was installed with a broom finish and then painted to achieve a particular bright blue color. The painted deck is slippery, especially when wet, and the homeowner is afraid to use the pool and deck due to safety concerns. How can we improve slip resistance?
Answer: In addition to aesthetics and durability, concrete pool decks must be both slip-resistant and easy on bare feet. This means they must have texture, but can’t be too coarse or rough. For new construction, there are many options for creating a slip-resistant surface. However, there are only a few options for existing concrete decks, such as roughing the surface by abrasive blasting, applying a concrete paint or sealer with a grit additive, or applying a textured concrete microtopping.
Abrasive blasting
Sand or shotblasting removes the paint and roughens the surface to increase slip resistance. Depending on the type of abrasive and blasting technique used, you can achieve various surface profiles and expose the fine and coarse aggregates. However, abrasive blasting can also fracture aggregates, create a dull surface appearance, and alter both the shape and color of the exposed aggregates. Because the method creates open surface pores, the surface may become more difficult to clean and prone to staining. So even though abrasive blasting can be an economical option, it may not be the best alternative when considering appearance and maintenance.
Paint or sealer with grit additive
Concrete paints and sealers can be very slippery when wet, even when applied over broomed or textured surfaces. By nature, they form a thin, nonporous, smooth coating that may smooth out the roughness of textured surfaces. Grit additives are commonly added to the final coat of a paint or sealer to offset the slipperiness.
There are three common grit additives: silica sand, aluminum oxide beads, and polymer grit. Additives are available in different grit sizes to create the desired surface roughness. Sand and aluminum oxides are heavy and tend to settle to the bottom of the mixing bucket and surface coating, creating application problems and reducing their effectiveness. These grits may also discolor clear sealers and distract from the natural color of the concrete, especially colored or stained concrete.
Polymer grit additives are micronized pieces of plastic specially designed to be added to concrete paints and sealers. The pieces of plastic are lightweight (low density) and translucent, so the grit stays in suspension and becomes transparent when added to sealers. Polymer grit additives do not affect the color of sealers or distract from the color of the concrete. Plus, polymer grit is kinder to bare feet than silica sand or aluminum oxide beads because the pieces are not as sharp.
For this project, the existing blue paint can be removed and the pool deck simply repainted using a polymer grit additive. To create a more architectural slip-resistant surface, consider removing the blue paint by abrasive blasting, staining the surface, and applying a concrete sealer with a polymer grit additive.
