Caption: FIGURE 6: X-Ray diffraction pattern of (a) cement and (b) VMA (Cel: cellulose; G: gypsum (CaS[O.sub.4]*2[H.sub.2]O); CS: anhydrite (CaS[O.sub.4]); A; alite; (B) belite
; C: calcite; cps: counts per second).
As the temperature is slowly increased to 1500[degrees]F, the aluminate and ferrite phases melt and some of the calcium oxide reacts with the silica oxide to form a calcium silicate mineral called belite
. As the temperature is increased further to 2700[degrees]F, much of the belite
is converted to a more reactive form of calcium silicate called alite which is key to the early strength of portland cement.
The anhydrate calcium silicate of alite and belite
phases, detected in initially set materials at =940, 515, and 456 [cm.sup.-1] , decreased and shifted to 996, 524, and 449 [cm.sup.-1], respectively.
One of such methods consists in a production of clinker substitute (belite
) with a lower lime saturation factor, characterized by lower sintering temperature of ca.
1) demonstrated the presence of tricalcium silicate (alite) as the primary clinker phase, as postulated previously by Henri Le Chatelier [2, 3] and observed by Tornebohm , and also indicated phases that are now called belite
(dicalcium silicate), tricalcium aluminate, ferrite, and periclase.
"New waste based clinkers belite
and lime formulations" Cement Concrete Research 38: 511- 21(2008).
New Waste Based Clinkers: Belite
and Lime Formulations, Cement and Concrete Research 38(4): 511-521.
However, since almost all raw materials containing Si[O.sub.2] in the structure, complete absence of belite
clinker in sulfoferrite impossible but sulfoferrite phase should dominate.
PC is a heterogeneous mixture of five mineral phases: 50-70% alite ([C.sub.3]S), 20-30% belite
([C.sub.2]S), 5-12% alluminate ([C.sub.3]A), 5-12% ferrite ([C.sub.4]AF) and 2% gypsum.
It should be noted that its binding part consists of calcium hydrosilicates of group C2SH2 according to Bogg's nomenclature, calcium hydroxide and residues of not hydrated clinker minerals, mainly belite
. This material has the appreciable secondary binding properties.
This paper describes the low temperature synthesis of belite
([beta]-[C.sub.2]S) from silica fume.
The addition of colloidal silica resulted in acceleration of silicate phases (alite ([C.sub.3]S) and belite
([C.sub.2]S)) dissolution and rapid formation of C-S-H phase in cement matrix .