Applicability of Electrical Resistance Method for Water Absorption Test on Cement Paste Using Mineral Admixture

While moisture is essential for the reaction of the binder in concrete, it is also known to be closely associated with degradation factors. Therefore, it is important to understand the internal water transfer for the maintenance and management of concrete structures. An embedded electrical resistance method, one of the electrical resistance methods, can finely grasp the moisture state in cement paste by the miniaturization of the electrode. However, its reproducibility and accuracy are still unclear, and it cannot be said to be a well-established method. It is also known that the pore structure becomes dense and the electrical resistance changes when mineral admixture is used because the electrical current flows through non-bonded water in hardened cement paste. Although the use of concrete with mineral admixtures has been increasing, there are still few examples of detailed studies on water transfer in this case. This study aims to examine the reproducibility and accuracy of the embedded electrical resistance method, and the results of the water absorption test using the electrical resistance method and the gravimetric method were compared by using cement paste with and without mineral admixtures. As a result, for almost all the mixture proportions, the moisture arrival distance at each measurement time measured by both methods was almost the same. The reproducibility of the electrical resistance method was confirmed by the fact that there was no significant variation in the arrival distance of moisture for each mixture. It may indicate that the electrical resistance method is applicable as a moisture transfer measurement method.