While comparing the permeability measured by beam-bending and thermopermeametry, we discovered a discrepancy that could be explained if the thermal expansion coefficient of the pore water in cement paste were higher than that of bulk water. We constructed a dilatometer similar to one used by Derjaguin et al. to measure the expansion of pore water directly. This work was done by Sonya Xu, who confirmed that the expansion of pore water in porous glass increased systematically as the pore diameter decreased below 15 nm. She then showed that the expansion of the pore liquid in cement paste was indeed high enough to bring the beam-bending and TPA data into agreement.
We decided to study this phenomenon in more detail. With funding from DOE, we are conducting experimental tests and - in collaboration with Prof. Steve Garofalini at Rutgers - molecular dynamics simulations. The results are described in several papers.