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Kang, Jang-Hwan;Jang, Jin-Yen;Koo, Han-Mo;Cho, Yoon-Ho
- International Journal of Highway Engineering
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- v.6 no.1 s.19
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- pp.25-36
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- 2004
The total length of paved roads in Korea is 67,265 Km, and among these roads, about 40% of the national highways and 98% of local roads are paved with asphalt concrete. The major distress to asphalt pavement is rutting and fatigue crack. The permanent deformation including rutting accounts for about 75% of this distress. UTW(Ultra-Thin Whitetopping), which is known for its high-quality performance in asphalt pavement with rutting and cracking, seems to reduce maintenance costs significantly if it is used as the maintenance/repair method for domestic asphalt pavement. In the research, static load test was conducted to establish a behavior of Whitetopping under traffic and environmental condition. It showed that the effect of the thickness of the concrete layer and the temperature change was significant. In addition, the tensile strain as the wheel load position was close to interior and edge of concrete slab were increased up to 75% of maximum tensile strain. It showed that joint spacing must be considered in UTW design procedure.
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Jung, Jong-Suk;Cho, Yoon-Ho;Lee, Kang-Won
- International Journal of Highway Engineering
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- v.7 no.1 s.23
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- pp.83-92
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- 2005
Maturity method is a non-destructive method for estimating in-place concrete strength as a function of time and temperature. The main objective is to use maturity method determining joint sawing and traffic opening time for whitetopping construction in Korea. Another objective is to investigate the influence of air temperature in the correspondence to slab temperature and maturity value. For determining the joint sawing and traffic opening time, thermachron i-button and strain gage were inserted in the fresh concrete in the slab and a maturity value was calculated at desired times. In-place strength was then estimated from a pre-established relationship between maturity values and compressive strength. The results showed that there are significant differences between the estimated strength obtained from maturity curve and in-place concrete strength. The reasons are that the gain of in-place concrete strength was influenced by several factors in the field such as curing conditions, air temperature, and wind speed etc. Also, the results showed that air temperature had significant influence on slab temperature and maturity value The slopes of maturity curves exponentially decrease as air temperature decreases. This means that maturity value sharply dropped as air temperature decreases.
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임채용;엄태선;유재상;이종열;엄주용;조윤호
- Proceedings of the Korea Concrete Institute Conference
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- 2002.10a
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- pp.507-512
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- 2002
In road pavements, it is known that cement concrete pavement has superior durability. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We developed special cement developing 1 day strength of over 30.0N/$mm^2$ to open the road within 1 day and workable time is maintained over 1 hour so that it can be used as ready mixed concrete. We performed experimental overlay construction with concrete and evaluated the properties of the fresh and hardened concrete. The flexural strength was over 5.0N/$mm^2$ and the compressive strength was over 30N/$mm^2$ at 1 day. So it is thought that the road can be open to traffic within 1 day after placement.
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