Table of Contents
Concrete is defined as a building material obtained by mixing cement, fine aggregate, coarse aggregate, and water in suitable proportions.
Constituents of Concrete
■ Cement – OPC or PPC
■ Fine aggregate – Sand or surkhi
■ Water ( With PH value not less than 6 )
■ Coarse aggregate – Small pieces of stones, bricks, or gravel
1. What is Salt Finish Concrete?
The salt finish concrete is an easy and cheap way to decorate floors which provides a mindblowing aesthetic beauty.
It’s done by pushing coarse rock salt into the surface of fresh concrete, permitting the concrete to be set, washing the salt away with a stream of water, and then applying sealant after drying the concrete.
Salt finish concrete is smooth and broom-finished concrete and also slip-resistant which makes it a better and ideal material for a pool deck.
Not only does it permit people to get around safely, but also helps objects like food carts, vehicles, and others to get around easier as well.
It is very necessary to seal the salt concrete with a sealant (acrylic or siliceous).
Salt Finish Concrete is majorly used in the Swimming pool area, Garden, House Backyard, and also in Parking Area.
i. Chemical Composition
The salt finish concrete surface is prepared by pressing coarse rock salt crystals using rollers on the freshly mixed concrete surface and washing it off with streams of water after the concrete is dried.
This procedure gives a rough subtle texture and skid resistance to plain or colored concrete.
The most commonly utilized salt crystal in salt finish concrete is Rock Salt.
Rock Salt is also known as Halite. Halite is naturally found as Sodium Chloride(NaCl).
If Concrete finish is done by using rock salt is known as Rock Salt Finish Concrete.
Rock salt doesn’t have any type of direct effect on the hardened concrete.
3. Preparation Process of Salt Finish Concrete
The preparation of salt finish concrete is done as like as normal concreting. The main work of salt finish starts after placing freshly mixed concrete in the formwork.
The surface is made smooth by using hand or bull floats which provide a high-quality surface finish.
Now following steps are carried out in the following steps:
a. Spreading of salt crystals
Salt Crystals found are:
4. Topaz Sulphur
5. Gypsum Mica
Coarse Rock salt (Halite) is a majorly utilized salt crystal in Salt finishing concrete.
The concrete placed in formwork is given to dry until when you press the thumb on the concrete, no concrete paste or grayish color should attach to your thumb.
If concrete paste attaches to your thumb then let it dries more.
Now, if no concrete paste attaches to your thumb, then the salt crystal is spread over the Concrete surface at a concentration range of 3 to 12 pounds per 100 square feet.
With the help of a trowel, salt roller, or float (Hand or bull) the salt crystal which was spread on concrete is then lodged into concrete by pressing it. Those salt crystals are lodged at half of their diameter.
The concrete surface is now cleaned gently with the help of a broom. Now, the concrete surface is allowed to dry for 24 hrs. This whole process is known as salting.
b. Removal of Salt Crystal
After completing 24 hours, the concrete where salt crystals were placed is washed out with the help of water. The water and salt completely or partially mix and leaves lodged crystal which is rinsed with the high velocity of the water and brush.
The concrete is fully dried so, you can directly apply water to the concrete without any tension. The crystal salt leaves a shallow mark on the concrete in a spot pattern which forms a good texture on the concrete surface.
c. Application of sealant
Before applying sealant, we should allow the concrete to dry completely. Clean the concrete with the broom, so that no dust is left.
The first coat of sealant is applied using a roller so that the sealant is completely applied on the concrete surface. After drying the first coat (i.e. within 2-3 hours), apply the second coat of sealant in a similar process to the first coat.
i. Rock Salt Finish Concrete
1. The size of the Rocksalt crystal must be between 1/3 to 1/8 inches.
2. The size of Rocksalt crystal should not be more than 3/8 inches in any case.
3. The Rocksalt crystal should not be pressed more than half of the diameter.
4. The concentration of rock crystal should vary according to the finish needed.
5. The concentration of rock crystal should vary between 3-12 pounds per 100 square feet.
6. The surface should be smooth and the marks left should be lined by a salt roller or float.
7. The Rocksalt crystal should be spread all over the concrete surface to obtain a smooth finish.
8. If the concrete surface is wet or too dried then, it will provide a poor-quality concrete finish.
9. The Rocksalt crystal should be washed off fully and cleaned with a broom, otherwise can cause discoloration in colored concrete.
10. The sealant should be applied carefully in two coats, otherwise, moisture/ water will be trapped on it.
4. Properties of Salt Finish Concrete
The properties of salt finish concrete are as follows:
1. It should be able to resist hammering action.
2. It should withstand chemical and weathering agencies.
3. It should be capable of resisting fire.
4. It should provide a smooth and broom-finished concrete surface.
5. It should be slip-resistant.
6. It should have high strength and durability.
5. Uses of Salt Finish Concrete
1. It is used as a decorative edge for swirl-troweled or broom-textured concrete.
2. It is also used in large panels bordered by bands of smooth concrete.
3. It is commonly used in the Swimming pool area, Garden, House Backyard, and also in Parking Area.
6. Advantages of Salt Finish Concrete
The advantages of salt finish concrete are as follows:
1. It is very cheap compared to other decorative concrete.
2. It requires less manpower, equipment, and materials.
3. It provides a smooth and broom-finished concrete surface which increases the aesthetic beauty of the structure.
4. It has high slip/skid resistance.
5. Salt has less effect on hardened concrete.
6. It saves a lot of time and cost.
7. Disadvantages of Salt Finish Concrete
The disadvantages of salt finish concrete are as follows:
1. Low temperature causes water and moisture to be trapped on the surfaces.
2. The moisture and water trapped in the surfaces increase pressure causing the concrete to crack.
3. If no sealant is provided then the concrete will absorb moisture near to it.
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Read Also: Curing of Concrete
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