It is cheap concreting which provides aesthetic beauty to concrete surfaces. Rock salt finish concrete is done by using different types of salt crystals.
One of the most commonly used salt crystals for salt finish concrete is rock salt. The concrete which is used by using rock salt crystals is known as rock salt finish concrete. It is also known as Halite. It is formed by sodium chloride (NaCl).
Rock salt finish concrete is a cheap & easy way to decorate concrete surface which provides aesthetic beauty to the concrete surface.
It is done by pushing coarse or extra rock salt into the surface of fresh concrete to set, & washing the salt away with a stream of water.
Rock salt concrete finish is smooth & broom-finished concrete, but it is slip resistant which makes it good & ideal material for a pool deck. Not only it allows people to get around safely, but it also helps objects like food carts, vehicles & others to get around easier as well.
It is necessary to seal the salt concrete with a sealant (siliceous or acrylic). It is commonly used in gardens, houses backward, swimming pool area & also in the parking area.
Properties of best rock salt Finish Concrete
- Rocks salt finish concrete should have high strength & durability.
- It should be capable of resisting fire
- It should withstand chemical& weathering agencies.
- It should provide a smooth & broom-finished concrete surface.
- It should be able to resist hammering action.
- It should be slip-resistant.
Manufacturing process of rock salt finish concrete:-
The preparation of rock salt concrete finish is done like a normal concreting. The main work starts after placing freshly mixed concrete in the formwork.
The surface is made smooth by using bull floats or hand which provide a high-quality finish surface. Now, the following steps are carried out,
- Spreading of rock salt crystals
- Removal of salt crystals
- Application of sealant
1) Spreading of rock salt crystals
Coarse rock salt is a majorly utilized salt crystal in salt finishing concrete. The placed concrete in formwork is given to dry until when the thumb on the concrete is pressed.
No concrete paste or grayish color should be attached to the thumb. If concrete paste attaches to the thumb then let it dries more.
Now, if no concrete paste attaches to the thumb, then the rocksalt crystal is spread over the concrete at a concentration range of 3-12 pounds per 100 sq. ft.
With the help of a salt roller, trowel, or float, the salt crystal which was spread on concrete is lodged into concrete by pressing it.
Salt crystals are pressed at half of their diameter. The surface of the concrete is now cleaned gently with the help of a broom. The concrete surface needs 24 hours to dry. This process is known as salting.
2) Removal of rock salt crystal:-
After 24 hours, the concrete is washed out with the help of water. The water & salt completely or partially mix & leaves lodged crystal which is rinsed with the high velocity of water & brush.
After the concrete is fully dried, the water is applied directly to the concrete without any tension. The salt leaves a shallow mark on the concrete in a spot pattern which forms a good texture on the surface of the concrete.
3) Application of sealant
Before applying sealant, the concrete surface must be dry completely. The surface is clean with the help of a broom so that no dust is left.
The first sealant coat is applied by using a roller, so that sealant is completely applied to the surface of the concrete. After drying, the first coat for two to three hours, apply the second coat in a similar process to the first coat.
Specification of rock salt Finish Concrete
- The size of rock salt crystal must be between 1/3 – 1/8 inches.
- The size of rock salt crystal larger than 3/8 inches should be avoided.
- Salt crystals should be pressed into the concrete surface up to a depth not exceeding half of their diameter.
- The concentration of rock crystal should vary between 3-12 pounds per 100 sq. ft. according to the type of finish required.
- The surface should be smooth & all the lines & marks are left due to the edge of the floats or rollers.
- It should be spread all over the surface of the concrete to obtain a smooth finish.
- Too wet or too dry concrete surface results in a poor quality concrete finish.
- The rock salt should be washed properly with water & cleaned with a broom which can cause discoloration in colored concrete.
The sealant should be applied in two coats, otherwise, moisture will be trapped on it.
Advantages and Disadvantages of Rock salt finish Concrete
- It is very cheap as compared to others.
- It requires less equipment, manpower & materials.
- It provides a smooth & broom-finished concrete surface which increases the aesthetic beauty of the structure.
- It has high skid resistance.
- Salt has less effect on concrete.
- It saves a lot of time & cost.
- If you do not provide sealant then the concrete will absorb moisture near it.
- During low temperatures, causes water & moisture are trapped on the surfaces.
- The water & moisture trapped in the surfaces increases the pressure causing the concrete to crack.
There are many uses of rock salt concrete finish. Some of the following are the uses of rock salt finish concrete;
- It is used as a decorative edge for swirl-troweled or broom-textured concrete.
- It can be also used in large panels boarded by bands of smooth concrete.
- It can be used to provide texture to colored concrete overlays.
- It is commonly used in parking, the house courtyard, and the area near swimming pools.