Wyniki 1-1 spośród 1 dla zapytania: authorDesc:"Helena Makyšová"

Geopolimeryzacja odpadów glinokrzemianów wykorzystywanych w chemii budowlanej DOI:10.15199/62.2019.4.11

  Geopolimery to bezpostaciowe trójwymiarowe materiały wiążące uzyskiwane z krzemianu glinu, które po raz pierwszy nazwano i stworzono w późnych latach siedemdziesiątych XX w.1). Geopolimeryzacja obejmuje reakcję chemiczną pomiędzy różnymi tlenkami glinokrzemianów (Al3+ w koordynacji tetraedrycznej) z krzemianami Geopolymerization is a process for transformation of waste aluminosilicate materials into building materials with excellent properties. Geopolymers are amorphous three-dimensional alumina-silicate binder materials which are first named and developed in the late 1970s1). Geopolymerization involves a chemical reaction between various aluminosilicate oxides with silicates under highly alkaline conditions, yielding polymeric Si-O-Al-O bonds2). The network consists of SiO4 and AlO4 tetrahedra-linked alternately by sharing all the oxygen. The Al3+ in IV fold coordination demands the presence of cations in the framework to balance the negative charge3). The geopolymers, also known as poly(sialates), have an empirical formula (1): (1) where M is a cation such as K+, Na+ or Ca2+; n is the degree of polycondensation and z is 1, 2 or 31). Alkaline activation solution most commonly contains (apart from water) hydroxides either alone4, 5) or in combination with silicates6-10). However, also carbonates11, 12), aluminates and sulfates13) can be used. Geopolymer synthesis can be carried out at elevated temperatures14- 17), also at ambient temperature18, 19), even at the microwave radiation20). In the recent times, the importance of geopolymer research has been shifted from the use of natural raw material to waste and by-products as source of aluminosilicate. Every material that contains silica and alumina - bearing phases is suitable for geopolymer production, like primary (kaolinite, illite) or secondary (fly ash, slag, red mud) raw materials. Among these, fly ash is the most explored material due to its aluminosilicate composition. [...]

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