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Title |
The Application of a Simplified Pullout Test for High-Strength Concrete
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Authors |
고훈범(Hune-Bum Ko) ; 전두진(Doo-Jin Jeon) ; 이민재(Min-Jae Lee) |
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DOI |
https://doi.org/10.11112/jksmi.2017.21.5.049 |
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Keywords |
파단형 볼트 ; 콘크리트 압축강도 ; 비파괴시험 ; 간이인발법 ; 인발하중 Break-off bolt ; Concrete compressive strength ; Nondestrutive test ; Simplified pullout test ; Pullout load |
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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.
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