C o n f i n e m e n t E f f e c t o f C o n f i n e d C o n c r e t e
665
Also, an increased strength of transverse reinforcement enhanced the confinement
effect and led to detachment of concrete.
Analysis of the Results
The strength enhancement rate according
to spiral yield strength is shown in Fig. 5.
The N series made using spiral of normal
strength was observed to have a strength
enhancement effect of about 30%
compared to the unconfined P series,
whereas the U series with the ultra-high-
strength spiral showed a 1.9-fold higher
strength enhancement effect compared to
the unconfined P series.
The NA specimen made of natural coarse
aggregate and the RF specimen made of
recycled coarse aggregate demonstrated
confinement performances with similar
stress enhancement caused by increased
spiral yield strength regardless of the type of
Fig. 5 Strength enhancement of tested specimens
aggregate used.
Conclusion
This experiment was conducted to assess the confinement effect of transverse
reinforcement according to the substitution ratio of recycled coarse aggregate, and the
following results were obtained for future application of recycled aggregate concrete as a
structural member.
(1) A comparative review of specimens made of natural coarse aggregate and
specimens fabricated based on varying substitution ratio of recycled coarse aggregate
showed similar confinement behaviors regardless of the recycled coarse aggregate
substitution ratio.
(2) Regardless of the recycled coarse aggregate substitution ratio, higher spiral yield
strength resulted in a confinement effect in regard to the compressive strength of the
specimen and stress enhancement effect.
Acknowledgments
This work was supported by Priority Research Centers Program through the National
Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and
Technology (2011-0022977). In addition, This work was supported by the Human
Resources Development of the Korea Insitute of Energy Technology Evaluation and
Planning(KETEP) grant funded by the Korea government Ministry of Knowledge
Economy(20114010203040).
References
Park. R. S, Bae. J. S., 2007, “An Experimental Research on the Quality Improvement of
Recycled Aggregate Using Surface Treatment Method”, Journal of Korean Society of
Civil Engineers, 27( 3), pp. 421-426, (in Korean)
Ministry of Land, 2009, “The quality standards for recycled aggregate”, Ministry of Land,
pp.83
400 600 800 1000 1200 1400 1600
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
NA
RF
f'
cc
/f'
co
Yield strength of spiral (MPa)
