Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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The Application of a Simplified Pullout Test for High-Strength Concrete

고강도 콘크리트에 대한 간이 인발시험법 적용

  • 고훈범 (인하공업전문대학 건축과) ;
  • 전두진 (인하대학교 건축공학과) ;
  • 이민재 (인하대학교 건축공학과)
  • Received : 2017.03.21
  • Accepted : 2017.06.28
  • Published : 2017.09.01
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Abstract

In the seventies, a number of researchers carried out experiments on pullout tests with prototype equipment, and the pullout test was certified as a reliable nondestructive testing(NDT) method for determining the strength of concrete. To estimate the strength of high-strength concrete, we propose a simplified pullout test that uses as a break-off bolt a standard 10mm bolt with a groove on the shaft, an insert nut, and a pullout instrument that includes a hydraulic oil pump without a load cell. To verify the advantages of the simplified pullout test(low cost, simplicity, and convenience), four wall specimens were tested with two levels of concrete strength, 30 MPa and 50 MPa, using a simplified pullout tester with a load cell. The pullout load and concrete compressive strength were measured every day until day 7, day 14, day 21 and day 28. It was found that the pullout load was very similar to the compressive strength. Therefore, we have verified that a simplified pullout test can be used to evaluate the in-place strength of high-strength concrete in structures. The prediction equation of the groove diameter of the break-off bolt(y) with the concrete strength(x) was derived as y=0.05x+3.79, with a coefficient of determination of 0.88 found through regression analysis.

1970년대에 여러 연구자가 시제품 시험장비를 가지고 인발시험을 실시하였으며, 인발시험은 콘크리트 강도를 결정하는 신뢰할 만한 비파괴검사 방법(NDT)으로 입증되었다. 우리는 고강도 콘크리트 강도를 추정하기 위하여 직경 10 mm볼트에 홈이 파인 파단형 인발 볼트와 인발너트, 그리고 로드셀이 필요 없는 오일 유압펌프를 포함한 간이 인발시험법을 제안하였다. 저비용, 간편성 및 편의성을 갖는 간이인발시험의 이점을 검증하기 위하여, 30 MPa 및 50 MPa 급 두가지 유형의 콘크리트로 제작된 4개의 모의벽체를 대상으로 로드셀을 장착한 간이인발시험을 사용하여 인발시험을 실시하였다. 인발하중과 콘크리트 압축강도는 재령 7일까지는 매일, 그리고 14일, 21일, 28일에 측정되었다. 시험결과 인발하중과 콘크리트 압축강도는 매우 밀접한 상관관계를 보여주었으며 따라서 인발하중이 현장에서 구조물의 고강도 콘크리트 강도를 평가할 수 있다는 것을 확인할 수 있었다. 파단형 인발볼트 직경과 콘크리트 강도와의 관계식으로 y=0.05x+3.79(x=콘크리트 압축강도, y=파단형 인발볼트 직경)이 도출되었으며 결정계수는 0.88로 나타났다.

Keywords

References

  1. ACI Committee 228. (2004), In-place methods to estimate concrete strength, American Concrete Institute, 6-9.
  2. ASTM. (2006), Standard Test Method for Pullout Strength of Hardened Concrete (ASTM C 900-06), 10 ASTM International, West Conshohocken, PA.
  3. Brencich, A. (2015), A Post-installed Insert for Pull-out Tests on Concrete up to 70 MPa, Construction and Building Materials, 95, 788-801. https://doi.org/10.1016/j.conbuildmat.2015.07.055
  4. Claus, G. P. and Ervin P. (1992), Pull-out testing by LOK-test and CAP-test, Dansk Betoninstitut A/S, 31-38.
  5. Kim, G., Lee, S., Kang, S., Kim, J., and Kim, K. (2007), Evaluation of In-situ Concrete Strength with Pull-out Testing at the Early Ages, Proceedings of the Korea Concrete Institute, 1087-1090.
  6. Ko, H., Cha, E., and Oh, K. (2017), Suggestion for the Simplified Pullout test of Normal Concrete Strength, Journal of the Architectural Institute of Korea, 33(4), 29-36. https://doi.org/10.5659/JAIK_PD.2017.33.3.29
  7. Ko, H., Lee, G., and Won, J. (2011), Development of Post- installable Pullout Bolts and a Loading Device for Evaluating Concrete Strength, Journal of the Korea Institute of Building Construction, 11(3), 229-237. https://doi.org/10.5345/JKIC.2011.06.3.229
  8. Komatu, Y., Kondo, G., and Morita, S. (1986), Variability of in-place Concrete Strength Evaluated by Pullout Test, Proceedings of Architectural Institute of Japan, No.1068.
  9. Latte Bovio, F., Latte Bovio, G., Brencich, A., Cassini, G., Pera, D., and Riotto, G. (2014), A New Pull-out Technique for In-Place Estimation of Concrete Compressive Strength, Advances in Materials Science and Engineering, 1-8.
  10. Lee, G., Ko, H., and Won, J. (2013), Effectiveness of a simplified Pullout Test using a Post-Installable Break-off Bolt, Research in Nondestructive Evaluation, Taylor & Francis, 24(1), 1-17. https://doi.org/10.1080/09349847.2012.675117
  11. Petersen, C. G.(1997), LOK-Test and CAPO-Test: Twenty Years Experience, Proceedings of Conference on Nondestructive Testing in Civil Engineering , British Institute of Non-Destructive Testing, Liverpool, U.K., 77-96.