若材齢時のコンクリート強度測定法に関する研究

抄録

The strength testing methods for the quality control of shotcrete being used as a main tunnel support of the NATM are all performed at present with destructive testing methods by obtaining specimens. In actual construction work, however, more rational and simpler testing method than the pull-out testing method for testing young-age strength of shotcrete has been sought for.
The authors estimated in this paper that the PARO tester used in printing factories for testing the hardness of paperrolls might be suitable to measure the range of young-age strength of shotcrete and that it would suit the purpose more effectively because it would not create much difference by the different impact directions. It was on these grounds that the authors verified the possibility of using the PARO tester for the purpose by carrying out some indoor tests.
In addition, other tests were carried out to compare it with the testing method using Schmidt Hammers, which was formerly tried in the past, and to see if the difference in measurement values will occur due to the different impact directions of the PARO tester used on the hexagonal specimens.
As the results of the subject tests, it has been confirmed that the proposed new testing method has good applicability for the estimation of concrete strength in range of 20-100 kgf/cm², and therefore, has good possibility of being used for the eatimation of young age strength of shotcrete.