Y. Aono, F. Matsushita, S. Shibata and Y.
Journal of Advanced Concrete Technology, 5(3) 313-325, 2007
Pore structural changes in hardened cement
pastes, subjected to drying and wetting/drying cycles, were studied at micrometer
and nanometer levels. Characterization techniques included Nuclear Magnetic Resonance
(NMR), nitrogen and water vapor adsorption, mercury intrusion porosimetry (MIP) and
under-water weighing. Coarsening of pore structure was observed with MIP and increase
in the true density of C-S-H was suggested by the result of under-water weighing.
Decrease in specific surface area due to drying was observed with nitrogen adsorption,
and water vapor adsorption associated with Excess Surface Work (ESW) analysis suggested
a development of cohesive structure in C-S-H. NMR confirmed polymerization of silicate
anion chains. The drying-induced coarsening of pore structure is probably attributed
to polymerization of silicate anion chains and development of cohesive structure