Photomicrographs of Belite

Photograph 7-25 Experimental laboratory burn with raw mix containing marl instead of quartz as a silica source. Resulting belite was well scattered in clinker and, to a minor extent, as nests. 1000°C for 30 min, 1425°C for 10 min. Very rapid temperature change. Average alite size = 20 pm. Clinker courtesy of Joe Garcia, Capitol Cement, San Antonio, Texas. (S A6645) 

Transmitted, plane-polarized light Field dimensions = 0.21x0.21 mm 

Photograph 7-27 Ragged belite crystals and belite coating on alite, one of which is twinned. Note abundant dotlike impurities in alite. Coarsely crystalline matrix with gray aluminate and relatively bright ferrite. Slowly cooled clinker. (S A6647) 

Photograph 7-28 Polished section of cement centrifuged in low-viscosity epoxy to produce a particle size and density gradation. Arrow on coarse particle near the base of the test tube (left) indicates alkali sulfate. Arrow on fine particle near the top of the cement (right) indicates gypsum. See Campbell (1986). (S A6648) 

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Photograph 7-63 Photomicrograph of clinker particle in a Class H oil-well cement, showing recrystallized belite classified by the writer as Type B. Note the finely microcrystalline interior of the crystal and near-total loss of lamellar structure. Lamellar extensions are not a criterion of this belite designation. Possible interpretations of Type B are slow cooling, reducing conditions, or both. (S 67842)... 

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