Treatments that Block Pores

From tests carried out on different concrete grades, it was found that it is increasingly difficult to obtain sufficient penetration of hydrophobic agents in concrete with increasing density and compressive strength. In standard concrete w/c = 

In general, it can be concluded that hydrophobic treatment of concrete is an effective and low-cost preventative measure against corrosion that may be caused by chloride ingress. The beneficial effect is mainly a strong reduction of chloride ingress, both in semi-permanent contact and in wetting/drying situations. The effective life in fully exposed atmospheric conditions is at least five years and more, probably much more, when protected from UV radiation by a layer of asphalt 

In addition, their effectiveness with regard to reducing the water absorption is relatively poor because essentially they form C-S-H gel, which is hydrophilic. On the other hand, pores are blocked for water vapour present inside the concrete, so the risk of damage due to freezing may increase, in particular in porous, mechanically weak, concrete. It seems that the trade-off between open (durable) and dense (effective) for sihcate-based pore blockers is unfavourable. 

Aqueous solutions of metal-hexafluorosihcates can be applied to concrete surfaces, which form Cap2, metal fluorides and silica (gel)  

No test results in terms of carbon-dioxide or chloride-penetration resistance of the inorganic pore blockers mentioned above are available. 

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Benzoyl peroxide is easy to use and recommended as first-line therapy in the treatment of mild to moderate noninflammatory acne. Benzoyl peroxide has a comedolytic effect that increases the rate of epithelial cell turnover and helps to unclog blocked pores. It also has antibacterial activity against P. acnes, which appears to be the main reason for the effectiveness of this product.13... 

On the basis of the unit-cell size and pore diameter, one can estimate that the distance between adjacent spherical mesopores of the LP-FDU-12 sample calcined at 450°C was 6 nm. This distance is likely to correspond to the pore entrance length. Given that the pore entrance diameter (in the narrowest point) was 2 nm, the pore entrance length-to-diameter ratio was 3 1, and thus one can readily envision that the reduction of the pore entrance diameter through the thermal treatment would eventually lead to the closure of the entrance. The obtained ordered closed-pore silicas were white powders. It is clear that the block copolymer template was removed without the formation of the carbon residue, which was observed in an ordered closed-pore silica templated by PEO-PS copolymer. Pluronic (PEO-PPO-PEO) copolymers usually decompose at relatively low temperatures, so they may be inherently more convenient than PEO-PS copolymers, whose PS block has an appreciable tendency to carbonize. 

Specifically, the improved solidification (cementation) technology involves the use of (a) a special dry powder admixture for the generation of a nonsoluble crystalline formation deep within the pores and capillary tracts of the concrete—a crystalline structure that permanently seals the concrete against the penetration or movement of water and other hazardous liquids from any direction (b) special nonmetal reinforced bars for enhancing the concrete block s tensile and compressive strengths and (c) a unique chemical crystallization treatment for the waterproofing and protection of the concrete block s surface. 

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