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Zastosowanie ultramaryny w tworzywach cementowych

Bensted J., Munn J.

Cement Wapno Beton

2012

R. 17/79, nr 6

409-414

Barwnik z ultramaryny może być stosowany do wytwarzania dekoracyjnych materiałów dobrej jakości, opartych na cemencie. Do ich wyrobu można stosować cement portlandzki, cementy wieloskładnikowe, lub glinowe, także w układach z wapnem. Materiały cementowe z zastosowaniem niebieskiej ultramaryny mają szansę znalezienia dla siebie miejsca na rynku, szczególnie do wykonywania zewnętrznych i wewnętrznych ścian w budynkach. Dotyczy to budynków, w przypadku których względy estetyczne odgrywają znaczną rolę. Barwniki z ultramaryny są same w sobie pucolanami i wymagają tylko małych dodatków aby rozwinąć właściwości pucolanowe. Wyeliminowanie wykwitów zapewnia stosowanie odpowiednich cementów, na przykład z dodatkiem żużla lub popiołów lotnych, w układach z wapnem.

Ultramarine pigments can be utilised for high quality decorative cementitious products. The cements employed for decorative purposes can be Portland, composite, extended, or high alumina, together with lime-based formulations. Cementitious products made using ultramarine pigments like ultramarine blue could find a niche market with usage for external or internal walls of buildings where aesthetic considerations are very important, and also for garden furniture. The ultramarine pigments are themselves pozzolans and only require small additions to generate real pozzolanicity. Efflorescence can normally be avoided by suitable usage of cements, such as extended cements (like slag and fly ash types), composite ones and HACs, together with lime-based products.

Nowe metody syntezy pigmentów ultramarynowych z użyciem zeolitów

Jankowska A., Kowalak S.

Wiadomości Chemiczne

2008

[Z] 62, 7-8

659-682

The natural ultramarine (lazurite, lapis lazuli) has been known and valued since the ancient times as semiprecious gem applied for jewelry, artistic works, decoration and painting. In Middle Ages it was used as excellent, but very expensive pigment. At the beginning of the nineteenth century a method of synthesis of artificial ultramarine has been discovered and it soon became a common inexpensive commercial product applied mostly for production of paints and as an optical brightener. The procedure included heating of the substrate mixtures (kaolin, sulfur, sodium carbonate, reducing agent) in kilns at high temperature (800°C). The technology of ultramarine production has not been substantially changed up to now, whereas the law regulations concerning environment protection imposed in the twentieth century could not accept a serious air pollution (SO2, H2S) always accompanying the production process. Therefore, searching for novel, environmentally friendly procedures becomes challenging. Ultramarine is an aluminosilicate with sodalite structure that contains sulfur anion-radicals (mostly •S3-) combined with Na+ cations embedded inside ?-cages. The sulfur radicals play a role of chromophores (•S3- blue, •S3- yellow). Sodalite is a zeolite and the sodalite units (?-cages) are constituents of structure of several zeolites (LTA, FAU, LTN, EMT). The use of zeolitic structures for encapsulation of sulfur anion radicals appeared very promising. The direct introduction of sulfur radicals from aprotic solutions of oligosulfides [27] was not successful but the thermal treatment of zeolites mixed with sulfur radical precursors (NaSn, S + alkalis) resulted in colored products analogous to ultramarine [24-26, 30, 31]. Zeolites A seem the most useful for preparation of sulfur pigments but other zeolites can be applied as well. The products of various colors (yellow, green blue and sometimes pinky) and shades can be obtained by choosing appropriate zeolite, radi-cal precursor, kind and content of alkaline cation in the initial mixture, temperature (400-800°C) and time of treatment. It was found that zeolite structure can be maintained upon the thermal treatment or it can be transformed (mostly towards SOD) under highly alkaline thermal treatment. The sulfur radicals can also be embedded inside smaller than ?-cages (e.g. CAN) which favors a generation of smaller radicals (i.e. •S2-) [39-42]. It is also possible to incorporate the sulfur compounds into zeolites during their crystallization and then a generation of radical upon heating. The sulfur pigments based on non aluminosilicate matrices (e.g. AlPO4-20) can be also obtained [38, 53]. Generally use of zeolites allows to obtain ultramarine-like pigments with broad range of colors under much milder than conventional conditions and with much lower emission of polluting agents.