抄録
A small-diameter drilling tester developed by the authors is one of the slight-destructive testers, with which the damage of materials tested can be very small. To apply the tester for checking the strength of compound materials e.g. Portland cement mortars, concretes etc., a series of experiments was carried out 1) to avoid the ill effect of cement powder discharged around a drill, 2) to avoid drilling coarse aggregates, and 3) to know the best magnitude of pressure for drilling. As a result, it is clarified that the testing method may be improved by considering the obtained data.
