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A Study on the Estimating the Ultra-High Strength Concrete using Rock Test Hammer

Rock Test Hammer를 사용한 초고강도 콘크리트 강도추정에 관한 기초적 연구

Nam, Kyung-Yong;Kim, Seong-Deok;Choi, Suk;Lee, Young-Do
남경용;김성덕;최석;이영도

  • Received : 2019.04.17
  • Accepted : 2019.05.24
  • Published : 2019.06.20

Abstract

This study examines the estimation of strength through a ultra-high strength concrete mock-up specimen using the rock compressive strength test hammer. According to the test result, the commonly used strength estimation formulae showed differences among them when the data of this test were applied. In additional, it show that these formulae underestimated the actual measurements further when the compressive strength was 30MPa or greater and deviated the distribution range of actual measurements in all strength ranges. The rock test hammer showed a higher correlation than type N Schmidt hammer regardless of the direction of hit for each type of W/B and the inclusion of coarse aggregate, and mortar showed a little higher correlation than concrete. As a result, it can be suggested that the coefficient of variation and the standard deviation of the mortar(2.26%/1.36) are lower than those of the concrete(4.06%/2.5), and the smaller the size of the coarse aggregate, the smaller the coefficient of variation and the more accurate the value.

Keywords

non-destructive test;rock test hammer;schmidt hammer;rebound hardness method

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