A Summary of Ono's Method for Cement Quality Control with Emphasis on Belite Color

The use of Ono's Method for cement quality control is standard in plants of the Onoda Cement Company and other producers in Asia. Widespread use of the technique is found in cement plants of North and Central America. Alite birefringence, alite size, belite size, and belite color are reported to correlate with kiln conditions and hydraulic activity. The present paper is a preliminary evaluation of belite color, particularly as it relates to 28-day mortar-cube strength. Thirty samples of portland cement clinker or cement have been examined microscopically to determine the color of belite after extraction of the matrix phases (aluminate and ferrite) with a potassium hydroxide-sugar solution. A positively sloping regression line was found with a plot of percentages of clear plus pale yellow belite crystals (single and nested) and 28-day mortar cube strength; negatively sloping lines were found with plots of percentages of single and nested yellow and amber crystals, plus crystals with abundant dotlike impurities. Both single and nested crystals exhibit these relationships with 28-day strength.