Natural pozzolanic material of tuff powder has prospect to be employed as concrete mineral admixture in hydraulic structure construction in western region.It focuses on the heat releasing behavior and hydration kinetic procession of tuff powder-medium heat Portland cement complex binder,using isothermal calorimeter and Krstulovic-Dabic model.Experimental results reveal that tuff powder is beneficial to reduce the hydration heat of complex binder,postpone the appearance time of hydration heat releasing rate peak,and also bring its value.Krstulovic-Dabic model has a good fitting effect to complex binder with a dosage of tuff powder less than 30%,and specific surface area no more than 800 m2/kg.Hydration kinetic procession of complex binder includes nuclear generation(NG)stage,interaction at phase boundary(I)stage and diffusion(D)stage.With the increase of tuff powder content or specific surface area of tuff powder,hydration kinetic procession of complex binder has trend to convert from NG→I→D to NG→D.
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