Effect of CuO on the formation of clinker minerals and the hydration properties

The purposes of this study are to explore the mechanisms of Cu element in clinker burning and hydration processes and to make effective use of waste containing copper in cement production. The effect of CuO on clinker mineral composition, C3S polymorph and size, Cu element distribution and state, compressive strengths, hydration products, non-evaporable water quantity and hydration heat release rate was analyzed by XRD, SEM, DTA, isothermal heat-conduction calorimetry, etc. Results show that as the amount of CuO increases the formation and growth of C3S grain are accelerated, R C3S is gradually transformed into M3 and the content of C4AF increases; a small quantity of CuO increases the 3-day and 28-day strengths and the hydration degree of clinker, but excessive CuO has adverse effects. Those effects of CuO on clinker burning process are attributed to the formation of low-melting Cu2O and the dissolution of CuO in C4AF which decrease the formation temperature of liquid phase and increase its quantity. The effects on hydration process result from the combined action of the following factors: the induction period is prolonged; the hydration reactions in the initial and acceleration periods are accelerated.