Assessing the Relationship between the Compressive Strength of Concrete Cores and Molded Specimens

Year 2012, Volume: 25 Issue: 3, 737 - 750, 19.07.2012

Ali Ergun , Gokhan Kurklu

Abstract

 There is no universal relation between the compressive strength of cores drilled from concrete elements and molded cylinder and cube concrete specimens. The strength of concrete cores depends on several parameters. The strength correction factors account for these parameters. In this study, the effects of diameters, length to core diameter ratio (l=L/D), test age, and coring orientation on the compressive strength of cores were analyzed with respect to the molded cylinder and cube concrete specimens. According to the test results; the compressive strength changes in 100 and 75 mm diameter cores were found to be more significant and reliable compared to those of 50 mm diameter cores. The strength decreased by 10% and 6% in 100 and 75 mm diameter cores drilled perpendicular and parallel to the direction of casting due to drilling damage. The compressive strength of cores with l=1.0 was equivalent to 92% of that of cores with l=2.0. Furthermore, it was found that the cores drilled perpendicular to the direction of casting and having a l=2.0 ratio was 83% and 71% of that of 28-day standard cylinder and cube, respectively. The correction factors between cores and standard cylinder and cube specimens were determined to assess the in-site compressive concrete strength. 

 

                Keywords: Compressive strength; concrete cores; molded

                specimens; evaluation; correction factors. 

 

Keywords

Compressive strength; concrete cores; molded specimens; evaluation; correction factors.

References

• Concrete Society Technical Report No:11. Concrete core testing for strength. The Concrete Society, London (1976).
• TS EN 13791. Basınç dayanımının yapılar ve öndökümlü beton bileşenlerde yerinde tayini (Assessment of in-situ compressive strength in structures and precast concrete components). Ankara, Turkey: Turkish Standard Institute; (2010) [in Turkish].
• TS EN 12504-1. Yapıda beton deneyleri, bölüm 1: karot numuneler–karot alma, muayene ve basınç dayanımının tayini (Testing concrete in structures - Part 1: Cored specimens-taking, examining and testing in compression). Ankara, Turkey: Turkish Standard Institute; (2002) [in Turkish].
• ACI Committee 214.4 R-03 M. Guide for obtaining cores and interpreting compressive strength results. (ACI 214.4 P-03), American Concrete Institute, Farmington Hills, MI, USA (2003).
• Özer, N.Ö. Evaluation of test results to determine the strength of concrete. MS Thesis, Middle East Technical University, Graduate School of Natural and Applied Sciences, Ankara, (1987). [15] ACI Committee 318 M. requirements for reinforced concrete. (ACI 318M- 83), American Concrete Institute, Farmington Hills, MI, USA (2004). Building code
• Johnston, C.D. Anisotropy of concrete and its practical implications. Highway Research Record, 423: 11-16, (1973).