Gunite and Shotcrete are forms of pneumatically applied concrete, meaning they are sprayed on with a high-pressure air hose. Crews shoot the material over a reinforcing network of steel bars.
As you research information on a potential new backyard swimming pool, you will often encounter the term “gunite.” What exactly is that anyway? Is it different from concrete? And what’s the deal with shotcrete—is that the same thing or something else?
Gunite pools provide unparalleled levels of design flexibility and aesthetic quality. Let’s take a look at some basics about this material, how it’s used in pool construction, how close it is to shotcrete, and the great advantages that both gunite and shotcrete deliver.
Three key elements unique to gunite pool construction
Known for its dependable structural strength, gunite is a concrete blend of sand, cement, and water that’s applied through a high-pressure hose. Once it cures (dries), gunite becomes rock hard, forming a thick, solid structure.
For decades, it has held a special place in swimming pool construction, where it is always paired with another strong building material—steel—as well as an interior finishing coat of plaster.
After a hole is excavated for a new pool, crews install a network of steel bars, known as rebar. Carefully placed at specific intervals, these metal rods form a cage-like frame that extends throughout the entire stretch of the future pool, as well as the spa if there is one. Extra steel goes into areas requiring especially high levels of reinforcement, such as a deep end or free-standing raised wall.
Set on concrete blocks, the cage is suspended several inches in the air so it does not touch the soil beneath it. This way, plenty of space remains to be filled in by fresh gunite material.
With the steel backbone in place, the pool is ready for gunite. Crews spray the concrete blend at high velocity onto the steel across the entire pool, creating the dense pool floor and walls. Gunite is highly adaptable to the pool form; it produces flowing lines, various contours, depths, and shapes—all coming together in a cohesive, visually appealing structure.
After the gunite properly cures, a third material is applied to complete a gunite pool: plaster. Composed of cement and marble dust, the smooth blend may also contain colored quartz aggregate for added durability and aesthetics. (For some pools, a high-end pebble plaster may be used.) Plaster is what actually waterproofs a gunite pool, and this final coating is what everyone sees as the pool’s gleaming interior surface.
Other critical elements go into building a gunite pool, including tile, plumbing, electric, and perimeter coping. However, what sets gunite construction apart from other types of pool is the gunite, steel, and plaster. And what sets the completed project apart is the incredible durability and design versatility that this trio provides. Both gunite and shotcrete are used to build swimming pool shells—the rock-hard vessels that can withstand pressure from shifting soil and the weight of thousands of gallons of water.
What’s shotcrete—and what’s the difference between it and gunite?