Belite-silica cement

The clinker composition of the first group is a classic belite Portland cement. However, as it was proved experimentally in the case of raw materials, composed of chalk with high silica ratio, the high strength cements can be produced [130]. 

Kato, H., Katumero, R., and Ushiyama, H. (1997) Properties of high strength concrete using belite-rich cement and silica fume (in Japanese). Semento Konkurito Ronbunshu 51,364-369 [ref CA 128/220688]. 

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)... 

Zivanovic (1995) presented a description of clinkers made with silica fume, instead of quartz sand, as the primary silica component in the raw feed. The silica fume made up approximately 3.0 percent of the feed. Alite crystal size was reported to be from 50 to 200 pm and belite grains were said to be rounded and between 50 and 60 pm. No mention of belite nests was made. The cements made with silica fume or tuff and a particular marl, compared to other cements not made with these materials, did not require as much grinding and produced higher 28-day mortar strengths. 

This modulus characterizes the ratio of solid to liquid in the clinkering of the material, because at clinkering temperature the Si02 is predominantly present in the solid phases (alite and belite), whereas the other two oxides occur in the liquid phase (melt). In industrial cements the silica modulus is generally between 1. Sand 3.0. 

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