Ippei Maruyama

In this study, the rate of change of microstructural re-organization in hardened cement paste under the first drying, which is caused by the colloidal nature of calcium-silicate-hydrate (C-S-H), is confirmed via 1H nuclear magnetic resonance relaxometry. Under the first drying, water evaporates from larger pores, while the interlayer water begins to increase. During the mass change, interlayer water continues to increase until reaching a peak. After the peak has been reached, interlayer water gr

In 2008, Nuclear and Industrial Safety Agency (NISA) (currently integrated to the Nuclear Regulatory Authority) launched a project to develop a soundness assessment method for concrete members subject to a radiation environment. Presently, the soundness of concrete members subject to radiation is evaluated based on whether the predicted fast neutron fluence and gamma-ray dose values are lower than specific reference values in Japan, which are 1×1020 n/cm2 and 2×105 kGy, respectively. These refer

The body of data about the reaction kinetics of cement has greatly grown in recent years, and in terms of techniques for the prediction of the resulting hydrate formation phases, databases contributing to thermodynamic equilibrium calculations have been developed and are growing increasingly sophisticated. On the other hand, though many studies on cement aim to contribute to concrete engineering and numerical model researchers have pointed out the necessity of shedding light on the relationship

The driving force of drying shrinkage of hardened cement paste has been attributed to RTln(h)/v with external relative humidity h and water molar volume v in theories of capillary tension and disjoining pressure. However, these theories fail to explain the considerable hysteresis observed in length-change isotherms. In this study, the sorption isotherm and length-change isotherm of cement pastes were determined with different water-to-cement ratios and cement types, and internal pressure of shri

Water vapor sorption isotherm measurement is one of the promising techniques to understand the microstructure of hardened cement paste, because it always gives a higher surface area than sorption isotherm measurements performed with other adsorbents such as nitrogen and argon, which implies that water molecules can probe the widest range of the microstructure of hardened cement pastes. When, at 20 °C, the water sorption measurement is conducted such as to last for a few days, a characteristic be