Z. Liu et Jj. Beaudoin, An assessment of the relative permeability of cement systems using AC impedance techniques, CEM CONCR R, 29(7), 1999, pp. 1085-1090
Aspects of the rapid chloride permeability test (AASHTO T277/ASTM C1202) we
re investigated using the AC impedance technique. Permeability and impedanc
e measurements were performed at different ages on the various cement paste
s prepared with or without silica fume and/or superplasticizer. The elastic
modulus of the pastes was also determined. The addition of silica fume and
/or superplasticizer had no significant effect on the elastic modulus of th
e pastes at the same water/cement ratio. The addition of silica fume signif
icantly in creased the impedance and decreased the total charge passed (tot
al coulombs) irrespective of the actual chloride penetration. The naphthale
ne sulfonate-type of superplasticizer had no significant impact on the impe
dance, and the total charge passed. Linear relationships between the impeda
nce, total coulombs, and initial current were observed. It is apparent that
the impedance is an equivalent indication of the relative permeability and
the total charge passed. Therefore, it appears possible to develop a new s
imple and rapid method to assess the relative permeability of the cement sy
stems using the AC impedance technique. (C) 1999 Elsevier Science Ltd. All
rights reserved.