Heterogeneous materials such as rock cannot be expected to have homogeneity so as to be used as structural materials. For example, in order to test large rocks more than one cubic meter, measures need to be taken against weaknesses such as internal cracks and fracture zones that can easily be overlooked in compressive strength tests. The impact-echo method could be available for evaluating strength and detecting internal defects in-situ concrete component with relatively good accuracy. In this study, measurements using the impact-echo method were carried for several types of rock specimens used at automobile crash safety tasting, and, by comparing the results with compression strength tests, the applicability of the impact-echo method for strength estimation of heterogeneous materials was evaluated.This work was supported by JSPS KAKENHI Grant Number 25420462.

• Sanghun LEE(Tohoku Gakuin University, Professor) Corresponding author
• Jun ABE(Tohoku Gakuin University)
• Shunsuke GOTO(Tohoku Gakuin University)
• Takao ENDO(Tohoku Gakuin University, Professor)
• TMitsuhiro TAKEDA(Tohoku Gakuin University, Professor)
• Masafumi KITATSUJI(Miyagi University, Professor)