Define Hydrophobic Cement
In hydrophobic cement, the cement grains are treated with admixtures that decrease their ability to permeate water. Among the most common hydrophobic admixtures are acidol, naphthene soap, oxidized petrolatum, etc.
A thin film of these substances forms close to the cement grains. It is achieved by grinding Portland cement clinkers with oleic acid to create hydrophobic cement that resists degradation when kept in adverse conditions.
Hydrophobic Cement Construction Process
The absorption films that form on the surface of hydrophobic cement are torn off by water and do not impede the cement's normal hardening.
1. In the initial stages, the strength gain is less because certain grains have hydrophobic films that prevent water from interacting with them.
2. Although the strength of this cement after 28 days is equivalent to that of an ordinary Portland cement, it takes longer to dry.
3. As with Portland cement, this special cement is made through the same process. A water repellent film is formed when cement clinkers are ground with Oleic Acid or Stearic Acid.
4. The chemical layer forms on the cement particle and prevents water from mixing and starting the hydration process during transportation or storage. The water repellent layer breaks during the mixing process, however, as a result of agitation, allowing the hydration to occur.
5. Using hydrophobic cement improves the frost resistance and water resistance of concrete by uniformly distributing its fine pores.
Oxygen Diffusion Coefficient of Hydrophobic Cement
1. Using measurements on concrete and diffusion cells on cement pastes and mortars, anyone can determine the oxygen diffusion coefficient through hydrophobic cement based materials fully immersed in water.
2. In cement paste, mortar, and concrete made with hydrophobic additives, oxygen diffusion is extremely high compared with negligible diffusion in cement paste or mortar made without additives.
3. Hydrophobic cement matrices immersed in water show oxygen diffusion coefficients comparable to unsaturated cement materials in air reported in the literature.
4. An empty cement matrix with hydrophobic pores appears to permit direct diffusion of oxygen dissolved in water.
5. The severe corrosion of steel reinforcement embedded in cracks in hydrophobic concrete immersed in aqueous chloride solutions can be explained by this observation.
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Published By
Arka Roy
www.constructioncost.co
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