APPLICATION OF AC IMPEDANCE TECHNIQUES IN STUDIES OF POROUS CEMENTITIOUS MATERIALS .2. RELATIONSHIP BETWEEN ACIS BEHAVIOR AND THE POROUS MICROSTRUCTURE

The relationship between A.C. impedance parameters and the structure o f porous cementitious systems was investigated. Theoretical equations relating the high frequency semicircle diameter to the descriptors of ionic concentration in the pore solution have been derived from the ap plication of electrochemical and surface chemical principles to these systems. It is apparent that there is a linear relation between the se micircle diameter and the reciprocal of the square root of ionic conce ntration. The semicircle diameter was also found to be inversely propo rtional to the product of porosity and mean pore size. These equations have been confirmed by experiment with porous cementitious systems. I t is concluded that the microstructure of porous materials can be char acterized by parameters determined by application of A.C impedance tec hniques.