Formation of aluminosilicate geopolymers from 1:1 layer-lattice minerals pre-treated by various methods: a comparative study

Jauni keramikas materiāli un tehnoloģijas

“…Viens no vairāk pētītiem alumosilikātiem augstāk minētā aspektā ir 1:1 kārtainais alumosilikāts -kaolinīts, 'baltajā' mālā -kaolīnā dominējošais mālainais minerāls [4,6]. Ir atzīmēts, ka silīcija jona palielināšana aktivējamā ģeopolimēru šķīdumā paaugstina iegūtā (temperatūru intervālā no 600 līdz 900 0 C) saķepinātā keramikas materiāla stiprību, kā arī attiecīgi sablīvēšanos [6,7]. Līdzīgi ir konstatēts, ka alkāliju katjonam K + vai Na + nav noteicošas ietekmes uz kristāliskās fāzes veidošanos alumosilikātu ģeopolimēros.…”

Use of Differential Treatment of Illite to Modify Their Structure and Properties / Diferencētas apstrādes pielietojums illītu struktūras un īpašību modificēšanai

“…One of more investigated processes to attain an increased compressive strength of materials containing clay minerals is by development of proper mix with, e.g., [4], [5], highly alkaline solution. Although 1:1 layer lattice alumosilicates, i.e., geopolymers, are mainly used for this preparation, it is also of interest to use 2:1 minerals such as 2:1 illite.…”

Comparison of Structure and Properties of Differently Treated Illite Clay and Products

“…The ability to attain an increased compressive strength of these materials by proper mix development with activating alkali solution is well documented [e.g. [4][5][6].…”

“…One of more investigated solid alumosilicate under highly alkaline conditions is the 1:1 layer lattice alumosilicate mineral -kaolinite [6].Although the mainly used in the preparation of 1:1 layer lattice alumosilicates, i.e.,geopolymers, it is also of interest 2:1minerals such as 2:1 analogue of kaolinite -pyrophillite with unitstructure Al 2 AlSi 3 O 10 (OH) 2 , in which the octahedral Al-O sheet isenclosed above and below by two tetrahedral Si-O sheets to form a repeating unit [7]. It is shown that attempts to produce fully reacted alumosilicategeopolymers from the crystalline 2:1 lattice mineral, pyrophillite, was unsuccessful.…”

“…It was suggested that inability to form viable geopolymers may be due to the retention of the crystalline 2:1 layer structure in pyrophillite and its dehydroxylated phase. According to the authors [6] the enclosed AlO 6 sheet by the upper and lower SiO 4 sheets is protected from alkaline attack to form a soluble aluminate species. It is shown that disruption of the crystalline 2:1 layer lattice by severe mechanochemical ball-or vibro-milling processing enables geopolymeric materials which attain reasonable hardness and strength at 60 0 C. These materials were not fully X-ray amorphous, but Xray powders show traces of zeolitic phases.…”