• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.252-253
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• 2014

This study is to XRD and image analysis of low carbon type recycled cement from waste concrete powder and cement raw materials. Waste concrete powder possible to low carbon type recycled cement in small part of additive materials. Also, low carbon type recycled cement using waste concrete powder is suitable for ordinary portland cement.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.123-128
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• 2013

This study was performed to evaluate the slump flow, air content, setting time, compressive strength, adiabatic temperature rise and diffusion coefficient of chloride used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furnace slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performances of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for low carbon green concrete material.

• Structural Engineering and Mechanics
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• v.69 no.4
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• pp.371-381
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• 2019

A hybrid prestressed segmental concrete (HPSC) girder utilizing low carbon materials was developed in this paper. This paper introduces the hybrid prestressing concept of pre-tensioning the center segment and assembling all segments by post-tensioning, as well as the development process of the low carbon HPSC girder. First, an optimized mix proportion of 60 MPa high strength concrete containing high volume blast furnace slag was developed, then its mechanical properties and durability characteristics were evaluated. Second, the mechanical properties of 2,400 MPa high strength prestressing strands and the transfer length characteristics in pre-tensioned prestressed concrete beams were evaluated. Third, using those low carbon materials and the hybrid prestressing concept, the HPSC girders were manufactured, and their structural performance was evaluated. A 30-m long HPSC girder for highway bridges and a 35-m long HPSC girder for railway bridges were designed, manufactured, and structurally confirmed as having sufficient strength and safety. Finally, five 35-m long HPSC girders were successfully applied to an actual railway bridge for the first time.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.11-17
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• 2013

This study was performed to evaluate the chlorine ion penetration resistance, chemical resistance and freezing and thawing resistance used ordinary portland cement, crushed coarse aggregate, crushed sand, river sand, fly ash, limestone powder, blast furance slag powder and superplasticizer to find optimum mix design of low carbon green concrete for structures. The performance of low carbon green concrete used fly ash, limestone powder and blast furnace slag powder were remarkably improved. This fact is expected to have economical effects in the manufacture of low carbon green concrete for offshore structures. Accordingly, the fly ash, limestone powder and blast furnace slag powder can be used for offshore structure materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.164-165
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• 2013

This study is on the performance evaluation of concrete being used the CaMg based low carbon cement(LCC) as a binder and the rapidly cooled electric arc furnace oxidizing slag(EAF slag) as a fine aggregate. When using the sand as a fine aggregate, compressive strength of the concrete using LCC, as a binder, was reduced 9% comparing with that of OPC concrete. However, when using the EAF slag as a fine aggregate, the compressive strength was increased by 9%. We found that combination LCC and EAF slag contribute to the strength properties of concrete.

• International Journal of Concrete Structures and Materials
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• v.8 no.1
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• pp.27-41
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• 2014

The use of carbon fibers (CF) and glass fibers (GF) were combined to strengthen concrete flexural members. In this study, data of tensile tests of 94 hybrid carbon-glass FRP sheets and 47 carbon and GF rovings or sheets were thoroughly investigated in terms of tensile behavior. Based on comparisons between the rule of mixtures and test data, positive hybrid effects were identified for various (GF/CF) ratios. Unlike the rule of mixtures, the hybrid sheets with relatively low (GF/CF) ratios also produced pseudo-ductility. From the calibrated results obtained from experiments, a new analytical model for the stress-strain relationship of hybrid FRP sheets was proposed. Finally, the hybrid effects were verified by structural tests of concrete members strengthened with hybrid FRP sheets and either carbon or glass FRP sheets.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3587-3595
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• 2015

Low-carbon eco-friendly precast concrete (PC) box structure has been recently was developed as an low-cost infrastructure of near-surface transit system. The concrete of PC box was manufactured by industrial byproducts such as ground granulated blast furnace (GGBF) slag, flyash and rapid-cooling electric arc furnace (EAF) oxidizing slag, its mechanical property and durability were estimated in this study. Based on the mechanical and durability tests, it is found that low-carbon eco-friendly concrete shows high initial compressive strength, more than 90% of design strength (35MPa), and high resistance to salt-attack, chemical- attack and freeze-thaw. Therefore, low-carbon eco-friendly PC box concrete technology is expected to contribute to the railway with low environmental impact.

• KIEAE Journal
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• v.15 no.1
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• pp.147-154
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• 2015

Environmental impact assessment techniques have been developed as a result of the worldwide efforts to reduce the environmental impact of global warming. By using the quantification method in the construction industry, it is now possible to manage the greenhouse gas is to systematically evaluate the impact on the environment over the entire construction process. In particular, the proportion of greenhouse gas emissions at the production stage of construction material occupied is high, and efforts are needed in the construction field. In this study, intended for concrete products for the construction materials, by using the LCA evaluation method, we compared the results of environmental impact assessment and carbon emissions of developing products that have been applied low-carbon technologies compared to existing products. As a result, by introducing a raw material of industrial waste, showed carbon reduction. Through a comparison of the carbon emission reduction effect of low-carbon technologies, it is intended to provide academic data for the evaluation of greenhouse gases in the construction sector and the development of low-carbon technologies of the future.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.75-90
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• 2002

Many existing concrete structures suffer from low quality of concrete and inadequate confinement reinforcement. These deficiencies cause low strength and ductility. Wrapping concrete by carbon fiber reinforced polymer (CFRP) composite sheets enhances compressive strength and deformability. In this study, the effects of the thickness of the CFRP composite wraps on the behavior of concrete are investigated experimentally. Both monotonic and repeated compressive loads are considered during the tests, which are carried out on strengthened undamaged specimens, as well as the specimens, which were tested and damaged priorly and strengthened after repairing. The experimental data shows that, external confinement of concrete by CFRP composite sheets improves both compressive strength and deformability of concrete significantly as a function of the thickness of the CFRP composite wraps around concrete. Empirical equations are also proposed for compressive strength and ultimate axial deformation of FRP composite wrapped concrete. Test results available in the literature, as well as the experimental results presented in this paper, are compared with the analytical results predicted by the proposed equations.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.199-200
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• 2023

Eco-friendly concrete contains only 5% of cement yet achieves equal or greater strength compared to conventional concrete, reducing salt-attack impact and hydration heat by more than 30% and ensuring higher construction quality for underground structures. Furthermore, eco-friendly concrete can reduce up to 90% of carbon dioxide emissions compared to traditional concrete, enabling a reduction of approximately 6,000 tons of carbon emissions for 1,000 of apartment units construction. This is equivalent to planting around 42,000 trees