• International Journal of Highway Engineering
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• v.19 no.3
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• pp.1-10
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• 2017

PURPOSES : This paper focuses on strength development according to the mix design with cement type and mineral admixture from laboratory and field tests in cool weather. METHODS : Two methods evaluated the mix design of concrete pavement in cool weather. Firstly, laboratory tests including slump, air contents, setting time, strength, maturity, and freezing-thawing test were conducted. Three alternatives were selected based on the tests. Secondly, a field test was conducted and the optimum mix design in cool weather was suggested. RESULTS : It is an evident from the laboratory test that a mix with type III cement showed better performance than the one with type I cement. There was a delay in strength development of a mix with mineral admixture compared to mix design without any mineral admixture. In the field test, type III cement+flyash 20% mix design proved the best performance. CONCLUSIONS : For concrete pavement in cool weather, mix design using type III cement could overcome the strength delay due to mineral admixture. Moreover, it is possible to make sure of durability of pavement. Therefore, strength and durability problems due to cool weather would decrease.

• International Journal of Highway Engineering
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• v.19 no.3
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• pp.11-18
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• 2017

PURPOSES : This study investigates the effect on concrete pavement accordance with the curing methods in cool weather and supports the best method in the field. METHODS : Two field tests evaluated the curing methods of concrete pavement in cool weather. Firstly, five curing methods were tested, including normal curing compound, black curing compound, bubble sheet, curing mat, and curing mat covered with vinyl. Concrete maturity was compared from temperature data. Secondly, normal curing compound and curing mat with vinyl, which showed the best performance, were compared in terms of maturity and join condition index. RESULTS:From the field tests, it is an evident that curing mat with vinyl accelerated the concrete strength. Therefore, it is possible to conduct saw-cut works in cool weather, which minimizes damage on concrete at joint. CONCLUSIONS : For concrete pavement in cool weather, using curing mat with vinyl as the curing method could overcome the strength delay. Therefore, strength and durability problems on concrete at joint due to cool weather would be fewer in the future.

• Journal of the Korean Society of Safety
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• v.30 no.6
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• pp.102-109
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• 2015

In this study, on the basis of the results of the field survey and the theoretical consideration for Korean Standard Specification for concrete durability and maintenance, the following conclusions are derived. From the survey, the prediction equation of carbonation depth for the southwest region in Korea is experimentally proposed, $y_p=5.865{\sqrt{t}}$, which predicts about 60mm of the carbonation depth for the concrete structures of 100 years, a 1st class of target endurance period, under a combined deterioration environment like a marine environment. Considering that the marginal value for a carbonation depth limitation under very severely marine environment is 25mm, in accordance with the Specification, it is found that the predicting carbonation depth for the concrete cover depths, 100mm and 60mm are 63mm and 29.4mm, respectively. In conclusion, according to the equation and the Specification, it is strongly required that the reinforced concrete structures with the cover depth under 100mm have to make a protection from combined deterioration factors by any methods like a surface coating, an increment of cover depth or an application of a special concrete.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.100-104
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• 2009

In this study, the space gamma dose rates in the apartments structured with concrete were measured in accordance with construction year. In addition, the environmental radiation rates coming from the subway platforms and the road tunnels were analyzed in the equivalent dose by multiplying the absorbed dose with the radiation weighting factors. The space gamma dose rates measured in apartments were higher than those of outdoor which was $0.08{\sim}0.11uSv/h$ in the natural conditions. Especially, the older construction year is, the higher becomes space gamma dose rate. The average gamma dose rates in the subway platforms were measured. In the case of Busan and Daegu subway, the earlier the opening year is, the higher becomes dose rate. However, the dose rates of Seoul subway Lines were high overall, regardless of opening year. Seoul subway Line 6 showed the highest value of 0.21uSv/h. The gamma dose rate in road tunnels was higher than one of the outdoor and increased with opening year like as apartment. In dose rate comparison of the concrete structures with the outdoor, therefore, the space gamma dose rate of indoor is higher than one of the outdoor and the older structures have a higher dose rate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.132-133
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• 2016

This research team has developed single silk white bubble sheets to be used as surface sheath curing material for spring, summer, and autumn. But though its effects for spring and autumn temperature conditions have been proved, there haven't been any studies for summer temperature conditions. Therefore in this study, single silk white bubble sheets and single silk transparent bubble sheets as well as aluminum metalizing single silk bubble sheets have been applied to actual box-frame apartment slabs in construction, in order to compare temperature backgrounds of the concrete and other qualities. Upon application, the temperature of concrete cured in summer temperature conditions showed excellent scores, being the lowest for aluminum metalizing single silk white bubble sheets, then single silk transparent bubble sheets. But the aluminum metalizing single silk bubble sheet gave off a harmful glare, so for actual use, white single silk bubble sheets are recommended.

• International Journal of Highway Engineering
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• v.4 no.1 s.11
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• pp.161-170
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• 2002

This study is a fundamental research for recycling waste polyethylene film(WPF) in asphalt concrete for roadway pavement. The objective of this study is to develop technology of making waste polyethylene asphalt mixture and evaluate properties of the asphalt concrete containing WPF. Asphalt concrete for surface course of pavement was produced through an appropriate mix-design using dense-graded and gap-graded aggregates. Marshall mix design, indirect tensile strength test, wheel tracking test and tensile fatigue test were performed. Test result showed that some WPF asphalt mixtures had a high tensile property and good resistances against rutting and fatigue cracking, compared with normal asphalt mixture.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.1
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• pp.11-19
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• 2016

This paper focuses on the estimation of durability and service-life of reinforced concrete structures in Wolsong Low- and intermediate-level wastes Disposal Center (WLDC) in Korea. There are six disposal silos located in the saturated environment. The silo concrete is degraded due to reactions with groundwater and chemical attacks, and finally it will lose its properties as a transport barrier. The infiltration of sulfate and magnesium, leaching of potassium hydroxide, and chlorine induced corrosion are the most significant factors for degradation of reinforced concrete structure in underground environment. From the result of evaluation of the degradation time for each factor, the degradation rate of the reinforced concrete due to sulfate and magnesium is $1.308{\times}10^{-3}cm/yr$, and it is estimated to take 48,000 years for full degradation while potassium hydroxide is leached in depth of less than 1.5 cm at 1,000 years after the initiation of degradation. In case of chlorine induced corrosion, it takes 1,648 years to initiate corrosion in the main reinforced bar and 2,288 years to reach the lifetime limit of the structural integrity, and thus it is evaluated as the most significant factor.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.707-719
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• 2003

The D&D work requires worker's safety and high reliability of operation because it has been processing in high radioactive environment. Therefore, it is necessary to select the dismantling items and applicable dismantling technologies and analyze the scenarios for selected items. In this paper, the main dismantling items were selected by the consideration of several factors, their 3D CAD models were constructed as well. The applicable dismantling technologies for each dismantling items were selected and their dismantling scenarios were setup. Finally the 3D graphic simulations for the shielding concrete, the RSR, and the core are performed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.47-48
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• 2018

The aim of the research is to suggest the compensating strength values depending on various managing periods of concrete based on the strength development model calculated with equivalent age method for OPC 100 % concrete. As a result, for 28 days of managing period, 6, and 3 MPa of compensating strength values were suggested when the temperatures were from 4 to 9℃, from 9 to 17℃, respectively. Additionally, for 42 days of managing period, 3MPa of compensating strength value was suggested when the temperature was from 4 to 10℃, and for 56 days of managing period, 3 MPa of compensating strength value was suggested when the temperature was from 4 to 5℃. Furthermore, for 28, 42, 56, and 91 days of managing periods, any compensating strength values were needed when the temperature were higher than 17, 10, 5, and 4℃, respectively.

• KIEAE Journal
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• v.8 no.1
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• pp.81-86
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• 2008

Due to the recent environmental problems, lots of studies on the solutions to reduce the environmental pollutions are on the way. In the field of construction, concrete that we are currently consuming approximately 1 ton each year is the most common and cheap building material. We must cut down on this preoccupied use of this material and develop an alternative material as recommended by the late environmental standards. In this regard, this study propose the 'yellow soil' as the main substance that composes the final state, 'yellow soil concrete'. This study also aims to analyze the physical and chemical performances of this concrete mixed with the yellow soil by comparing it with the cement and assesses the possibility of its application to the cement. The results of the experiment shows that, assuming the solidity of the cement concrete to be around $210kg/cm^2$ (20.58MPa), the solidity of the yellow soil combined material may be around 45%~55% in terms of the range of W/B use, 200 to 400 in the per unit fission amount and less than 2% in the addition proportion of admixing agents. But the scope of the optimal concoction amount of the yellow soil concrete should better be limited as following. 40% to 50% in W/B, 300 to 400 in the per unit fission amount and less than 2% in the addition of admixing agents.