The authors have been studying the strain sensitive materials which are based on conductivity change resulting from structural change in percolation system. In this study, we have developed a maximum strain memory sensor, which enables to detect damage to structures easily even after a large earthquake. To confirm the performance as the sensor, tensile tests embedded into concrete specimen have been conducted. As a result, it is discovered that this sensor is sufficiently effective to diagnose cracks in the concrete structure.

A compression test for concrete-mortar-concrete specimens has been developed to investigate the compression behavior of the joint mortar between two ultra-high-strength precast concrete columns. A method for estimating the compressive strength from the strength values of constituent materials is proposed. Long-term loading tests confirmed that the joint mortar remains stable over a long period of time even under high stress. The compression test was also used as a joint mortar strength control test for a practical building. The test results indicate that the newly developed test can be used to obtain reliable strength test results under accuracy conditions of specimen fabrication and precise loading.

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