Shotcrete Additives for Swimming Pools

Shotcrete additives for swimming pool construction

In swimming pool construction, you might wonder which cement additives or shotcrete admixtures to use, or what differentiates gunite and shotcrete.

Shotcrete is a method used to shoot/spray (i.e. pneumatically place) concrete at a high velocity. Cement is a specific ingredient used in mixing shotcrete for swimming pools and other construction projects, and it consists of calcium, aluminum, silicon, and other ingredients.

To enhance the various properties of cement, certain cement additives are available for use in applications such as swimming pool construction. These additives may help improve waterproofing capabilities, increase durability, shorten curing times, and increase overall strength.

In achieving the best results with shotcrete for swimming pools, installers may also use specific types of cement for these projects. One of the most popular types of cement for swimming pools and other applications is Portland cement. This type of cement consists of four primary compounds, including dicalcium silicate, tricalcium silicate, tetra-calcium aluminoferrite, and tricalcium aluminate. Additionally, cement in swimming pools may include certain pozzolans, or supplemental cementitious material (SCM). Commonly used SCMs for swimming pools include fly ash and slag, which increase durability and workability.

Shotcrete for Swimming Pool Construction

Shotcrete refers to the unique method of mixing and spraying concrete to form a shell in swimming pool construction. Historically, Gunite was a specific tradename referring to the pneumatic application of dry sand-cement mixtures, but the term “shotcrete” developed in its place to avoid using tradenames in technical standards. Today, professionals may use the term “gunite” when speaking of dry-mix shotcrete, while shotcrete applies to wet-mix concrete. Compared to gunite, shotcrete using a wet mix forms a more consistent and durable coating, and the application process takes less time to complete.

Gunite and shotcrete mixes used in swimming pool construction consist of a combination of Portland cement, aggregates, and sand. To supplement this foundation, gunite and shotcrete may use certain types of admixtures to improve properties such as workability, durability, and water reduction. One frequently used type of shotcrete admixture is an accelerating admixture, which dry-mix processes may use to optimize early strength while reducing rebound and dust, and wet-mix processes use primarily for early strength and rapid set times. Condensed silica fume, or microsilica, is another popular admixture for shotcrete, as it reduces permeability while boosting durability.

Select the Right Mixture for Swimming Pool Construction

Depending on the application’s specific requirements and location, you can choose the right shotcrete mixture and admixtures to get the best results. Using the ideal cement, concrete, additives, and admixtures will give swimming pool installations the durability and waterproof structure they need to hold up in many environments.