HYDRATION PROPERTIES OF COMPOSITE CEMENT WITH A LARGE AMOUNT OF BLENDING MATERIALS

Hydration properties for the three kinds of composite portland cement made of a large amount of slag, fly ash and limestone were studied by micro-calorimeter, chemically combined water, X-ray diffration, thermogravimetric analysis, scanning electron microscope, etc. Results show that the characteristics of hydration heat of the composite portland cements are distinctively different from those of the portland cement. For the blended composite portland cement, the early hydration rate is lower than that of portland cement, but the late hydration rate is increased quickly due to the secondary hydration of slag and fly ash. Hydration products of the blended composite portland cements are mainly CHS gel, ettringite and calcium hydroxide crystals, but the content of calcium hydroxide is apparently lower than that of normal portland cement.