The XRD and Raman analysis of sintered targets shown that increasing the sintering temperature changes the balance between alite (C3S) and belite (C2S) phases and decreasing content of portlandite (CH), calcium silicate (CSH) and ettringite
(Aft) phases (figure 2).
An increase in the percentage swell of the bentonite-lime mix with the addition of the phosphogypsum was attributed to the formations of ettringite
crystals on the surface of the bentonite plates, within a colloidal calcium silicate and aluminate hydrates (Kumar et al.
Lou, "Study of effects of two expansion sources of ettringite
and periclase in cement," Journal of the Chinese Ceramic Society, vol.
Figure 3 shows that the main hydration products of the reference (J) group are quartz, C-S-H gel, Ca [(OH).sub.2] crystal, and ettringite
. It can be found that the most abundant hydration product is Ca[(OH).sub.2]
With regard to solidified samples, the ettringite
was produced which had the property of expansion.
The chemical precipitation method mainly includes lime precipitation , barium chloride precipitation [17, 18], and ettringite
([Ca.sub.6][Al.sub.2][(OH).sub.12][(S[O.sub.4]).sub.3] 26[H.sub.2]O) precipitation methods .
Adsorbents such as sulphuric acid-treated peanut shell, hydrocalumite, ettringite
, AlP[O.sub.4], biopolymeric materials, aluminum-based water treatment chemicals, hardened cement paste, cement minerals, aluminum oxides, iron oxyhydroxides, iron-coated sand, and zero valent iron [16-23] have also been tested for Se removal.
The hydrated product of the high-water-expansion material is mainly ettringite
, and its molecular formula is ([Ca.sub.6][Al.sub.2][(OH).sub.12]*24[H.sub.2]O)*[(S[O.sub.4]).sub.3]*2[H.sub.2]O.
Another session talked about the fire protection through ettringite
materials by Dr Gautam Bhattacharya.
The gypsum is also highly soluble and the sulfates react with the aluminates to form the mineral ettringite
. If all the sulfate reacts before all the C3A does then the level of the sulfate ions decreases and the ettringite
becomes unstable and undergoes a second reaction over several hours to form monosulfate which is lower in sulfate.
these reactions lead to the formation of hydration product such as hydrated silicate gel (CSH phase) and calcium hydroxide (portlandite), ettringite
[1-3].In the last decade, calcium silicate cement has received great consideration in dental and orthopedic surgery since they have the important property to set in a biological medium such as blood, simulated body fluids (SBF) and Saliva being, therefore they can be used for dental and orthopedic surgery [1-4].
The calcium sulfate band at 1153 [cm.sup.-1] has been shifted to 1113 [cm.sup.-1] that was assigned to polymerized sulfate in ettringite
(hydrated calcium aluminate sulfate) phase .