Alkali fiber glass

Acids and alkalies were used to decompose the fiber to cellulose. The alkali digester process, developed in 1899, is still used. Fiber glass reinforcement must be removed mechanically before the mbber can be reclaimed. A highly efficient method involves hammer mills and reel beaters to separate the fiber from the mbber an air current subsequendy drives off the fiber. 

Fibers commonly used for concrete reinforcement include polypropylene, steel and alkali-resistant glass. The fibers are often of short length (<30 mm) and are randomly mixed in concrete. 

Synonyms/Tiade Names Fiber glas , Fiberglass, Glass fibers, Glass wool [Note Usually produced from borosilicate low alkali silicate glasses.] ... 

When the coloring of latex-modified mortar and concrete is required, alkali-resistant, weatherproof pigments are used. Furthermore, it is important that the pigments do not obstruct the stability of polymer latexes and the hydration of cements. Alkali-resistant glass, steel, polyamide, polypropylene, polyvinyl alcohol (poval), aramid and carbon fibers are employed as mixable reinforcements. Reinforcing bars for ordinary cement concrete are also used for the reinforcement of the latex-modified concrete. 

Due to the absence of Ca(OH)2 in the calcium aluminate cement paste a higher durabiUty of glass fibers was expected in fiber reinforced composites. Majumdar [26] proved that the calcium aluminate cement composites had much better mechanical properties, but only the case of alkali resistant glass. 

Majmndar, A.J, Singh, B., and Ali, M.A. (1981) Properties of high alumina cement reinforced with alkali resistant glass fibers. Journal of Materials Science 16,2597-1607. 

Bentur, A., Ben-Bassat, M., and Schneider, D. (1985a) Dnrability of glass-fiber-reinforced cements with different alkali-resistant glass fibers. Journal of the American Ceramic Society 68,203-208. 

The first step in the attack of water on the bare surface of an alkali-free or near-alkali-free glass fiber is its adsorption. The adsorbed water molecules hydrolyze foe siloxane bond by protonation of the oxygen atom, and yield a highly hydroxylated fiber surface. 

A. J. Majumdar, Alkali-resistant glass fibres, in Strong Fibers, W. Watt and B. V. Perov, editors, pages 61-85, Elsevier Science Publishers, North-Holland (1985). 

Alkalis hydrolyze glass fiber-reinforced polyester resins, drastically changing their mechanical properties. Phthalic- and isophthalic-based glass fiber-reinforced polyester resins suffer property reductions at room temperature shortly after exposure begins. Bisphenol HEX type resins are more resistant vinyl ester resins are the most resistant [32]. 

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