Concrete Natural Swimming Pools

Concrete Options for Natural Pools

For those desiring a more traditional pool shape, alternatives like cement or Rastra blocks can be considered, as well as prefabricated concrete water tanks. While these options are not as environmentally friendly as gravel and stone, they can still reduce chemical and energy consumption by utilizing plant-based filtration systems instead of mechanical filters and chlorine for water clarification.

Concrete Water Tank Pool

Concrete water tank natural swimming pool owned by Sophie Kovic, the Natural Pool Girl

A 100,000-liter concrete water tank provides a relatively inexpensive, fast, and easy option. The tank needs to be excavated into the ground, with the fitting of a hydrostatic valve, and a section of the wall should be cut out to allow water flow into the filtration zone. The filtration zone must then be poured in reinforced concrete and sealed to the pool edge.

Pouring a concrete pool requires precision, as the right mix and density are crucial to prevent cracking. Due to the complexities involved, it is advised against do-it-yourself construction.

For those experienced in concrete work, here are some tips: Use a mix ratio of 4 parts Portland cement to 1 part sand, and cover the compacted soil with fiber mesh, a rubber liner, old carpeting, or newspaper to provide a stable surface for the concrete. After pouring the concrete, apply a 1/8-inch coat of stucco to waterproof the pool since concrete is porous.

Rastra Block Construction: An Alternative to Concrete

Constructing a pool using Rastra blocks offers a viable alternative to traditional concrete structures. These blocks, crafted from a combination of recycled polystyrene and cement, possess several advantages over concrete. They are lightweight and easy to install. Kenton Knowles, a builder from Global Homes in Baldwin City, Kansas, successfully built a Rastra-block pool measuring 16×32 feet for a cost of approximately $1,600 in materials.

1. Excavation and Preparation
   To begin constructing a Rastra-block pool, first, excavate a hole slightly larger than the pool’s intended dimensions, providing ample workspace. Most individuals prefer a pool depth of 5 feet. For the pool’s bottom, you have the option to either pour a concrete slab or use a rubber liner. Line the bottom with gravel and install a drain and backflow preventer. Next, secure one section of Rastra block along the edges of the slab using rebar.
2. Connecting the Structure
   Fill the cavities of the Rastra blocks with concrete to establish a solid connection throughout the structure. To hold the blocks firmly in place, apply expanding foam sealant between courses and at joints. It serves as an adhesive. Ensure the blocks are waterproof by applying two coats of stucco.
3. Finishing Touches
   Backfill the space between the sides of the pool and the Rastra block with soil. The perimeter of the pool can be elegantly finished by extending stones from the top of the blocks or by incorporating vegetation at the edge.