Abstract
Concrete surface are expected to change in color according to change of moisture of environment, because there are many pores of them. The effect of moisture on color, particularly brightness of cement paste surface and the mechanism of the change were studied. First, brightness of cement paste of various water cement ratios, which were kept at various moisture environments for more 3 months, were measured. It was found out that they have hysteresis loops in brightness as well as in weight. Pore structures of them were furthermore studied through measurement by the mercury intrusion technique and observation by the AFM. The mechanism of the hysteresis in brightness was explained using a model composed of pores of cone shapes and ink-bottled ones.
