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
661
CONFINEMENT EFFECT OF CONFINED CONCRETE
ACCORDING TO REPLACEMENT RATIO OF RECYCLED
COARSE AGGREGATES
Young-Seek Kim
1
, Chan-Yu Jeong
2
, Sang-Woo Kim
3
, Kil-Hee Kim
4
1
Ph. D. Candidate, Dept. of Architectural Engineering, Kongju National University, 275 Budae-Dong,
Cheonan, Chungnam 330-717, South Korea
2
Master’s Course, Dept. of Architectural Engineering, Kongju National University, 275 Budae-Dong,
Cheonan, Chungnam 330-717, South Korea
3
Research Assistant Professor, Dept. of Architectural Engineering, Kongju National University, 275 Budae-
Dong, Cheonan, Chungnam 330-717, South Korea
4
Associate Professor, Dept. of Architectural Engineering, Kongju National University, 275 Budae-Dong,
Cheonan, Chungnam 330-717, South Korea
Abstract
This paper estimates the structural behavior of recycled aggregate concrete confined
with spiral reinforcement. The recycling of aggregate from demolished concrete helps to
reduce environmental and economic problems. The main test parameter was designed
to be the type of aggregates and the yield strength of spirals. All the specimens had a
diameter of 150mm and a height of 300mm. The specimens can be divided into two
groups, based on the type of coarse aggregate used. The yield strength of spiral
reinforcement was varied from 472MPa to 1430MPa. From the experimental results, the
structural performance of recycled aggregate concrete specimens confined by steel
spirals was similar to that of natural aggregate concrete specimens regardless of spiral
reinforcement ratio.
Keywords:
Recycled aggregate, spiral, ultra-high strength, confinement effect.
Introduction
Recently, there has been an increase of demolition and reconstruction of aging or
functionally degraded buildings and this trend is expected to continue. The wastes
generated from the demolition and reconstruction are recycled, buried in landfill,
incinerated or disposed in the sea. Of these methods of disposal, landfill and incineration
have resulted in environmental pollution and destruction of ecosystems, and are
considered problematic from social and environmental perspectives.
Waste concrete, which accounts for a significant amount of construction waste, is not
very harmful and is produced in large amounts. Thus, using it as recycled aggregate is
expected to reduce treatment costs as well as the environmental problems arising due to
burial in landfill, and allow waste concrete to be used as an alternative resource to
mitigate the problem of aggregate shortages.(Park 2007)
Accordingly, in this study, an experiment was carried out to assess the confinement
effect of reinforced concrete member manufactured using recycled aggregate with the
yield strength of spiral as a variable.
Materials
The natural coarse aggregate used in the experiment had maximum diameter of 25mm,
density of 2.61g/cm
3
, and water absorption of 0.68%, while the recycled coarse
aggregate had density of 2. g/cm
3
and water absorption of 2.55% in accordance with the
quality standards for recycled aggregates established by the Ministry of Land, Transport
and Maritime Affairs. The maximum diameter of the recycled coarse aggregate was
25mm, as with the natural coarse aggregate. As for the fine aggregate, natural fine
aggregate was used. The physical properties of the coarse and fine aggregates are
summarized in Table 1.
