Yuji KAGAWA

Evaluation of Water Migration in Concrete in both Liquid and Vapor Phase

SupervisorFTakumi SHIMOMURA

Concrete is porous material with various size of poring internally, and it usually contains water in it. Water in the pore exists in the state of liquid water or moisture. Water influences the corrosion of the reinforced concrete. Therefore, it is important to understand the amount and the phase of water in the pore for the performance estimation of a concrete structure.
Previous research denotes that the water migrates somewhat in liquid phase even in unsaturated concrete. However, it is too microscopic to observe the water migration in concrete pores directly. Therefore, there is no experimental example verifying actual water movement mechanism. Moreover, the occurrence of the movement in liquid phase has not been proved yet.
In this study, chloride ion is used as a kind of tracer, because that has unique characteristics, that is, electrolyzed in liquid water, and stays at the position where liquid water is evaporated. As a result, the presence of the movement of liquid water in the unsaturated concrete was experimentally confirmed.
The density of the chloride ion in the drying area was increased. Therefore, the liquid water movement in the state of unsaturated was able to be confirmed experimentally in the cement mortar test piece with the concrete pore structure.
An increase in the density of the chloride ion is seen in the drying area where the amount of moisture is a little. Therefore, the liquid water movement is superior in the concrete pore structure in case saturation ratio is relatively high. While, the vapor movement is superior when it is small.