Microwave study of hydration of slag cement blends in early period

Abstract

Microwave technique were used to investigate the early hydration of slag cement with different slag percentages, different activators and different amount of activator. It is found that higher slag cement causes a higher dielectric constant ε{lunate} and a shorter induction period. But higher slag cement samples have very different electrical conductivity a compared with that of pure cement, their σ curves have two extra bumps in 9-14 h and 22-24 h. We found that the addition of 2% NaOH and Na2SO4 results in large changes in ε{lunate} whereas the addition of 2% Ca(OH)2 causes a little change in ε{lunate}. Addition of 2% Ca(OH)2 decreases the a but addition of 2% NaOH and Na2SO4 increases the σ. We also found that the greater the amount of Na2SO4 the smaller the ε{lunate} but the greater the σ. The relation between the compressive strength results and the ε{lunate} and a results are also discussed. © 1995.