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Hydrophobic cement includes admixtures that reduce the wetting capacity of cement grains. The standard hydrophobic admixtures are acidol, naphthenesoap, oxidized petrolatum, etc. These substances form a slim film close to cement grains. Hydrophobic cement is acquired by grinding portland cement clinker with a film-forming substance such as oleic acid in order to decrease the rate of deterioration when the cement is kept under adverse conditions.
When water is kept to hydrophobic cement, the absorption films are torn off the surface and they do not in any way, prevent the normal hardening of the cement. However, in the initial stage, the gain in strength is less as hydrophobic films on certain grains prevent interaction with water. However, its strength after 28 days is equal to that of ordinary Portland cement.
When hydrophobic cement is utilized, the fine pores in concrete are uniformly distributed and thus the frost resistance and the water resistance of such concrete are considerably improved.
1. Oxygen Diffusion Coefficient of Hydrophobic Cement
The oxygen diffusion coefficient through hydrophobic cement-based materials fully immersed in water is determined by potentiostatic measurements on concrete and by the use of a diffusion cell on cement pastes and mortars.
The obtained results show that very high oxygen diffusion occurs through cement paste, mortar, and concrete made with hydrophobic admixture as opposed to negligible diffusion through the reference cement matrix without admixture.
Moreover, the oxygen diffusion coefficients measured through hydrophobic cement matrices immersed in water are comparable with those reported in the literature for unsaturated cement materials in air.
These experimental results appear to confirm that oxygen dissolved in water directly diffuses as a gaseous phase through the empty pores of a hydrophobic cement matrix.
This could explain the severe corrosion of steel reinforcement embedded in cracked hydrophobic concrete immersed in an aqueous chloride solution observed in various works.
2. Uses of Hydrophobic Cement
The uses of hydrophobic cement are as follows:
a. Utilized in longer storage periods and incredibly wet climatic necessities.
b. Majorly utilized in Tunnel construction as the underground repairs are complex and expensive.
c. These types of cement are employed in the construction of dams, spillways, underwater constructions, and submerged structures.
d. Employed in the structures that are revealed to rain or rain puddling, such as green roofs, other sorts of roofs, parking structures, and plazas.
e. Employed in drainage system works and manholes.
f. Employed in water treatment plants, dams, and retaining walls.
g. It can repair leaky pipes and basements without having to prevent the leaking.
3. Advantages of Hydrophobic Cement
The advantages are as follows:
✔ This cement can be utilized in the building of water structures such as dams, spillways, or other submerged structures.
✔ The strength of this cement is identical to that of ordinary portland cement after 28 days.
✔ It can be utilized in cold weather conditions as well.
4. Disadvantages of Hydrophobic Cement
The disadvantages are as follows:
✔ It is very expensive.
✔ Cannot be used when the temperature is below 40 degrees Fahrenheit.
✔ Application is labor-intensive.
✔ Does not work on frozen surfaces.
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