This study investigates the effectiveness of rapid (6-h) pH and electrical conductivity measurements of a lime-pozzolan solution for direct assessment of reactivity during initial screening of pozzolanic materials. A new analytical method is proposed to estimate the consumed portlandite using electrical conductivity and pH measurements. Correlations between pH and electrical conductivity test outcomes (estimated portlandite consumption) and results of three other direct and indirect tests were determined using available data from seven different materials. The tested materials were brick powder (BP), dolostone powder (DS), class C fly ash (FA), waste glass powder (GP), lightweight aggregate fines (LA), pottery cull (PC), and silica fume (SF). Good correlation was found between the strength activity index (SAI) and the estimated portlandite consumption using electrical conductivity. Similarly, the consumed portlandite estimated using pH measurements had good correlations with thermographic analysis (TGA) and Frattini test results.
Elyasigorji et al. (2026) studied this question.