粗骨材の熱膨張係数のひずみゲージによる測定

抄録

The coefficient of linear thermal expansion of concrete is affected by the constituent materials. Coarse aggregate, which occupies about 40% of the concrete volume, is said to have a large effect on the coefficient of linear thermal expansion of concrete. The coefficient of linear thermal expansion of coarse aggregate is often measured using rock cores. However, it may be difficult to collect the rough aggregate core. Therefore, we examined a method for measuring the linear thermal expansion coefficient of coarse aggregate particles using a strain gauge. As a result, we clarified the influence of the measurement method on the measurement results and the coefficient of linear thermal expansion of the coarse aggregate particles. Specifically, the presence or absence of surface treatment on the coarse aggregate particles and the difference in the rate of temperature change have almost no effect on the measurement result of the coefficient of thermal expansion. In addition, the length of the strain gauge used has a slight effect on the measurement result of the coefficient of thermal expansion. Although the coefficient of thermal expansion of coarse aggregate particles of the same lot is different, the range is about 3 x10^-6/°C. For chert and sandstone, it was revealed that the difference between the minimum and maximum principal strains is within about 25%. It was revealed that the coefficient of thermal expansion of limestone tends to be small on average of multiple particles, but there may be particles that shrink individually. The variation in measurement results differs depending on the type of coarse aggregate, and it is necessary to increase the number of measurements of coarse aggregate with large variation.