DEVELOPMENT OF PORTABLE DRILLING SURFACE STRENGTH TESTER FOR HISTORIC STRUCTURES

As for historic structures, aged deterioration such as weathering is conspicuous on the surface of brick and stone structures.The purpose of this study is to devise a tester which can measure surface strength distribution of structures by slight-destructive inspection. As the first step, a tester has been devised experimentally, and the material and the form of the drill bit have been determined by the basic experiments. As a result, we found that the most suitable quality of the meterial for a bit tip was a diamond, and column type one was desirable judging from the stability of the drill speed. A surface strength test using this diamond bit on an actual terra cotta has demonstrated the possibility of definite evaluation of the relative strength and thickness of the glaze, and the relative strength of the foundation. Evaluation of the absolute strength of materials will be discussed in the following steps.