Reinforcing Gunite Pools

Minimum Reinforcing

1. Reference 156 or 200 high-tensile steel fabric in a single layer

2. A second layer of steel fabric must be added to cover the area. It should extend 1 meter from each side.

3. 4 x Y10 high-tensile bars in continuous ring beam spacing 100 mm. 2 x 1 x Y10 bars, double reinforcing or steel fabric.

Alternate Method

At 200 mm centers, place R8 rods throughout the pool and tie at each intersection. Notice: Each square meter of steel should contain approximately 2.8kg steel for both methods mentioned above.

Reinforcing Handpicked Pools

1. About 4kg of steel reinforcement bars per square meter.

2. Continuous steel ring beam

Guniting

1. Standard mix shall contain 1 part Portland cement and 4 parts sharp, well-graded river sand. The aggregate must be free of organic impurities, and the maximum particle size should not exceed 10mm.

2. Gauge boxes can be used for mixing on-site or ready-mixed with a guarantee from the supplier of 4:1 mix.

3. 2 pockets of Portland cement to concrete wheelbarrows of 5 levels of gunite-sand aggregate 7 mm.

4. Gunite average thickness to be 100mm

5. To ensure adequate compaction, the gunite must be applied at a pressure not to exceed 3 bars. The distance between the nozzle and the gunite surface should be between 900 and 1200mm.

6. The gunite application to the pool floor shall be done to cover the sides and sides to approximately 300mm above the bottom. The reinforcement should then be covered. The remaining sides and coves must then be shot. All rebounds must be swept away. Gunite that forms lumps or other irregularities from excessive application shall be removed.

7. The soil floor should be compacted if necessary before gunite is applied.

8. To ensure concrete mix coverage on both sides, reinforcement steel/mesh should be raised.

Material Strength – Handpicked Swimming Pools

1. Mixture of Portland cement on aggregate and double-washed river sand. The minimum size is 13 mm

2. Concrete should be 150mm thick on average

3. Concrete should have a strength of 30 m.p.a. At 28 days.

4. A cement mixer can be used to mix concrete on-site.

5. Concrete must be placed within three hours after adding water to the mixture.

6. Ring beam should be 300 mm by 150 mm

Curing Period – Handpick / Gunite

The shell must be watered daily by the owner for the first five days following its construction.

Coping and Paving

If paving exceeds 1 meter in width or borders another wall, an expansion joint is not necessary. This joint should be filled with an acceptable expansion joint material. Fill the joint to the maximum depth of the thickness of the coping tile.

Mosaic and similar Tile Paving

You can lay mosaic or similar tiles at the waterline, with an approximate width of 150 mm.

Paving Surround

You will need to compact the ground in layers of 150mm or any other necessary piling.

Elec.

1. It is possible to install a time switch.

2. All wiring must be done according to local authority and Eskom regulations.

Pump/Motor Filter

Please refer to the manufacturer’s specifications for the size.

Fittings and Piping

All piping must be of class 6 when P.V.C. Use rigid piping 50 mm O.D. (outer dimension): or 50 mm I.D. When Polythene pipe is used, the inner dimension will be 50 mm I.D.

Final Interior Finish

Marble plaster must be used for interior finishing. A steel trowel is required to apply the finish. Finish must not be less than 6mm in thickness. An approved mixture must be used in marble plaster.

Specifications for Renovations

Marble Plaster Finish for Pools (Used to finish a Gunite/Handpick Concrete Pool).

These specifications only apply to there-marbeliting or painting of existing marble plastered, plastered or painted pools.

i. You must ensure that the marble plaster is not bonded to any other material.

ii. The marble plastered surface must be chipped in order to create a binding between marble plaster and the surface to be covered. Each chip must be at least 3mm deep and no further than 10 cm from the other. If the covered surface is painted, glass-fibred, or epoxy coated, it must be prepared for a marble plaster finish.

The marble plaster must first be prepared according to the supplier’s instructions.

Mix marble plaster with water until you get a stable mixture. Calcium chloride flakes should be added to the mixture at 160g per 40kg bag in rain or cold.

ii. You will need to apply a 6mm layer of marble plaster using a trowel. Once smoothed down, you can use a scraper to do this.

iii. The pool must be refilled at the request of the renovator.

Specifications for Fibreglass Linings and Repairs

Instructions for lining swimming pools with G.R.P. These guidelines apply to both new and older concrete pools as well as pools that have been relined with marble plaster.

The “cosmetic” and the “resurfacing” linings for a leaking pool that have only plaster cracks are, in fact, cosmetic. They do not form a structural part of the pool shell and provide a water barrier. Only pool shells that conform to NSPI specifications should have the liner installed.

Primer/Seal Coat: This is the first layer of a low-viscosity resin that will allow concrete and marble plaster to penetrate. It should be left to gel for at least four hours before further work can begin.

Preparation

Clear the pool and remove all dirt, sand, or another residue. Check for cracks, leaks or crumbling plaster. Pools must be cleaned and repaired before Primer can be applied.

If the liner is not to be carried under the coping stone, then a horizontal groove should be cut as high above the water level as possible to a depth of at least 20mm. This groove should then be dovetailed-shaped, and then the liner (fiberglass) should be secured into the groove.

Liner (Fibreglass).

It is preferable to use a wax-free, chemical-resistant thixotropic pre-accelerated resin for safety reasons.

Cosmetic Linings

a. A single layer of 450gsm is possible for pools in good condition.

b. For pools that need repair, you will need at least 2 x 300gsm layers (for a total of 600 gsm) of the mat.

Resin / Glass Ration

It must be at least 3:1 by mass, i.e., 25 % glass content per mass.

Lining Operations

Each section of the pool surface should be broken down into smaller sections. If the resin is not pre-accelerated, the catalyst and its content can alter gel times at different temperatures.

The glass fiber mat should be cut and trimmed to fit the sections. The resin should be evenly applied to the pool surface. Next, the glass fiber mat must be rolled out using an air bubble removing roll. This is done to ensure that the laminate is consolidated and remove air bubbles. You can apply additional resin to “dry spots”. Before applying the topcoat, the resin and fiberglass layer must gel. After the walls have been finished, the liner can be applied to the floor. The liner should be applied in sections, starting at the shallow end and working up to the steps. The minimum thickness of the liner to be applied to floor-to-wall joints is 100mm.

Top Coat Resin (Flow Coat).

Before applying the topcoat, the pool must be sanded by hand. To ensure a reasonable pot life (gel times), the Top Coat must first be catalyzed (and possibly accelerated if needed). The resin must then be stirred well (be careful not to add air to the resin) to ensure uniform wax distribution. The flow coat can be applied using a paintbrush or a pigmented brush. Avoid dark colors as they can cause wax bloom (white marks and blotching due to high wax content surfacing).

Before the inspection, the flow coat should be fully cured (approximately 24 hrs). Any areas not complying with the inspection should be sanded to remove any waxy residue and then painted with the flow coat.

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