Activation effectiveness of some chemical substances for Portland cement blended with fly ash

The activation effectiveness of some inorganic chemical substances on Portland cement blended with fly ash was investigated by means of compressive strength determination for the cement mortar specimens.Meanwhile,the characteristic of the hydration products and the microstructure of the hardened cement paste of the Portland cement blended with fly ash were also studied by means of XRD analysis and SEM observation.The results shows that activators used enhance the evolution of reactivity of the fly ash,especially at early age,hence increasing the strength of the cement.XRD analysis and SEM observation also show that hardened cement paste blended with fly ash and added with activator presents denser microstructure feature,surface of the fly ash particles tend to be coarser,as compared with that of reference specimen.At the same time,the reduction of the intensity of the diffraction peak of portlandite and quartz indicates that the chemical reaction between the active component in fly ash and portlandite released from the hydration of cement is enhanced under the presence of activator.