AN A.C. IMPEDANCE-BRUGGEMAN ANALYSIS OF THE EFFECT OF VARIOUS SUPERPLASTICIZERS ON INTERFACLAL TRANSITION ZONE PERFORMANCE IN MORTAR

摘要

Binder-aggregate interfacial characteristics in portland cement mortars and concrete influence ionic and fluid transport. The efficiency of percolated networks is dependent on the quality of the interfacial transition zone (ITZ). The influences of superplasticizing admixtures on the relative performance (in terms of electrical conductivity) of the ITZ in portland cement mortars were investigated. A.C. impedance spectroscopy and a model analysis based on the Bruggeman asymmetrical effective medium theory were employed as the basis for the arguments presented. The effect of three superplasticizer types -polynaphthalene sulfonate (PNS), polymelamine sulfonate (PMS) and polycarboxylate (PC) - on the relative character/conductivity of the ITZ was determined. The quality of the ITZ varies with water-cement ratio, superplasticizer type and dosage, volume fraction of aggregate and degree of hydration. The relative performance of the superplasticizers (with respect to the ITZ) is discussed.