Journal of the Korean Geo-Environmental Society ISSN:1598-0820(Print) 2714-1233(Online) 한국지반환경공학회 논문집

The Korean Industrial Standards (KS F) have a various regulations for measuring the weight of dried soil and rock. However, if the dried weight is measured in air after drying at 110±5°C or 105±5°C, a weight singularity occurs, in which the weight decreases and then increases as the measurement time continues. In this study, basaltic rock from Ulleung Island was oven dried at 40 to 110°C. The weight was measured on an electronic scale with a sensitivity of 0.0001g (0.1mg) to find weight singularities. A method to easily determine the dry weight using the weight singularities was presented. As a result of analyses of the singularity of rock specimen according to temperature, the singularities were appeared in the temperature range of 40 to 110°C, and the weight of the singularity was smaller as the heating temperature increased. In particular, the weight singularity duration appeared, and the duration of the singularity was shorter as the heating temperature increased. The results of the convection measurement experiment showed that the cause of the singularity is the convection phenomenon caused by the contact of the heated rock with the air. The weight decrease of oven dried rock occurs when the effect of convection is dominant over the effect of air moisture absorption. Conversely, the weight increase of rock occurs when the effect of air moisture absorption is dominant over the effect of convection.