Abstract
In snowy cold regions, the base course and subgrade are exposed to freezing in winter and increased water content during the thaw, and these layers see decreases in load bearing capacity from freeze-thaw. Therefore, it is crucial to understand the frost penetration depth and number of freeze-thaw cycles of the pavement, and the variation in water content of the material, towards establishing paving methods that are appropriate for snowy cold regions. In this study, we conducted a basic study on evaluating the freezing and thawing of pavement body materials such as base course and subgrade according to their changes in electrical resistance. We prototyped a sensor on which many electrodes were placed at regular intervals, installed the sensor in base course material and subgrade soil ground in a laboratory, and measured the electrical resistance when the materials were subjected to freeze-thaw. It was found possible to use the electrical resistance values to determine whether the materials were frozen or not. We also installed the prototype sensor in ground outdoors in order to determine whether the soil was frozen or not by using a self-recording device that enables AC voltage measurements. We found that the sensor can measure the soil's freezing and thawing continuously in the depth direction, and that it is effective for measuring the frost depth of the soil.
