• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4192-4200
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• 2015

In this paper, dispersibility of steel fiber is improved mixing with form for material development of protection and blast resistant structure sprayed concrete. And it is developed a high toughness cellular sprayed concrete material using steel fiber. Oversupply form for dispersibility improvement of steel fiber is mostly fade away through sprayed, finally it is satisfied with the proper mixing ratio under 3 % ~ 6 %. This is considered for compressive strength and flexural toughness. Test results of compressive strength showed superior strength capability in 28, 56 days, also flexural strength and flexural toughness is great. Then oversupply form is enhanced for dispersibility of steel fiber and I think that it did not cause decreasing of strength. But analysis results of pore structure through image analysis failed for a great spacing factor and specific surface area. This is largely measured in spacing factor because air content have a grate evaporation effect for sprayed.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.227-232
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• 2006

This article presents the results of experimental study that investigates the effect of filler and shrinkage reducing agent influencing on the strength properties of MMA-modified polymer paste that was produced to develop the surface-repair and coating materials of the concrete structures. Results show that the flexural and compressive strengths of the polymer paste increased 29 and 27%, respectively, when the aluminum hydroxide completely replaced the calcium carbonate as the filler Furthermore, when the shrinkage reducing agent was used 30%, both strengths decreased about 29% comparing to when the agent was not used. As in the cases of flexural and compressive strengths, the adhesive strength increased as the content of aluminum hydroxide as the filler increased, and it decreased as the content of shrinkage reducing agent increased. The adhesive strength with a dry concrete substrate turned out to be $30{\sim}40%$ higher than that with a wet concrete substrate.

• Journal of agriculture & life science
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• v.44 no.4
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• pp.21-27
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• 2010

This study was carried out to investigate the properties of woodceramics made from woody part of Broussonetia Kazinoki at different carbonizing temperatures of $600^{\circ}C$, $800^{\circ}C$, $1000^{\circ}C$and $1200^{\circ}C$. The physical and mechanical properties increased with increasing carbonizing temperature. The highest mean values of density, bending strength, Brinell hardness and compressive strength were $0.62g/cm^3$, $79kgf/cm^2$, $203kgf/cm^2$ and $129kgf/cm^2$, respectively. There were close correlations between density and bending strength, Brinell hardness and compressive strength and MOE and MOR.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.155-162
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• 2011

The structures that use the bridge plates are considered to have advantages such as short work term, excellent economical efficiency and low maintenance cost. Bridge plates are being widely used for water ducts and eco-corridors as replacements of reinforced concrete ducts. Bridge plates are deep and have greater pitch as compare to conventionally deep corrugated steel plate. They are expected to be increasingly used in the future. The structures that use bridge plates have two forms, such as arch type and box type. The arch type structures are designed based on the compressive strength, and the box type structures, based on the moment in the plate member. In this study, the ultimate strength and moment strength of the connection part of the specimens were examined by their thickness. Static and bending tests used to evaluate the performance of bridge plate. Finally, These results were used in the design process.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.39-46
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• 2010

Concrete strength relationship between various strength properties was presented through experimental data from concretes made from different sources of coarse aggregates and fine aggregates, and different amount of cement contents. In the strength relationship were included compression-flexure, compression-split tension, compression-modulus and flexure-split tension. A total of 61~81 data sets were analyzed while each data set is composed of 3 to 4 experimental test data. Using the proposed strength relations, a procedure to reliably estimate modulus values from the LTPP field test section was suggested. Core specimens were taken from 10 LTPP sections on the expressway as well as 4 sections on the national road. Then compressive strengths and modulus were determined in the lab. Finally concrete modulus was averaged with the estimated values by using the derived relationship and experimental values.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.1-12
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• 2017

This paper concerns the structural behavior of high-strength concrete beams with compressive strength of 80 MPa subjected to flexure. Main test variables were nominal yielding strength of longitudinal rebar including normal strength rebar(SD 400) and high strength rebar(SD 600), reinforcement ratio from 0.98 to 1.58% and beam section size with $200{\times}250$, $200{\times}300mm$. The nine beams were cast and tested under flexure. The study investigated ultimate flexural strength, load-deflection relationship, crack patterns, failure patterns and ductility of the test beams. Test results indicate that when rebar ratio increased flexural strength increased and ductility decreased. In addition, the number of cracks increased and the crack width decreased as the reinforcement ratio increased. The yield strength of rebar did not affect significantly load-crack width relationship. Nonlinear analysis of test beams was performed and then test results and analytical results of ultimate load were compared. Analytical results of high-strength concrete beams overall underestimated flexural strength of test beams.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.677-689
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• 1998

In relation to concentrically loaded compression, this research is to describe, analyze, and evaluate the design strength in steel stud. The similarity and difference among load and resistance factor design specification for cold-formed steel structural members (AISI), cold-formed thin gauge members and sheeting (EC3 part 1.3), and German draft (DASt-Richtlinie 016) are introduced, discussed, and systematically evaluated. Especially, the effective width and global instability problems (flexural buckling and torsional flexural buckling) are here implied in this research. The design axial strength by dual standards (AISI and EC3) is calculated and compared using the example.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.389-398
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• 2010

The flexural strength of composite HSB I-girders under a positive moment was investigated using the moment-curvature analysis method to evaluate the applicability of the current AASHTO LRFD design specifications to such girders. A total of 2,391 composite I-girder sections that satisfied the section proportion limits of the AASHTO LRFD specifications was generated by the random sampling technique to consider a wide range of section properties. The flexural capacities of the sections were calculated inthe nonlinear moment-curvature analysis in which the HSB600 and HSB800 steels were modeled as an elasto-plastic strain-hardening material, and the concrete, as a CEB-FIP model. The effects of the ductility ratio and the compressive strength of the concrete slab on the flexural strength of the composite girders made of HSB and SM520-TMC steels were analyzed. The numerical results indicated that the current AASHTO LRFD equation can be used to calculate the flexural strength of composite girders made of HSB600 steel. In contrast, the current AASHTO LRFD equation was found to be non-conservative in its prediction of the flexural strength of composite HSB800 girders. Based on the numerical results of this study for 2,391 girders, a new design equation for the flexural strength of composite HSB800 girders in a positive moment was proposed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.299-306
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• 2023

Environmental pollution problems are occurring due to the negative treatment of basalt waste in Jeju Island. This study identifies the characteristics of permeable block with basalt with physical and chemical adsorption mechanisms and examines their applicability and functionality as building materials. This experiment is basic data for evaluating the functionality of the permeable block by analyzing flexural strength, compressive strength, permeability coefficient, carbon dioxide, and fine dust adsorption rate by producing a permeable block using a basalt waste rock. As the basalt waste stone replacement rate increased, the flexural strength and compressive strength tended to decrease, and as the replacement rate increased, the water permeability coefficient, absorption rate, carbon dioxide, and fine dust adsorption rate tended to increase. Therefore, it is judged that the permeable block using the basalt waste rock is superior to the existing permeable block.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.131-132
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• 2017

As the building is becomes bigger and larger, it can lead to big damage in case of fire. Also, tunnel, machine room and underground joint are spaces that can cause high temperature fire above 1,350℃ in case of fire. Therefore, a refractory material is need that can be withstand in high temperatures for long time. One side, the composition of oyster shell is CaCO₃ of 90% or more. It is expected that it will be possible to use it as a high calcium natural material which is the material of the refractory board. According to, Study on bending, compressive strength of mortar according to temperature and heating time change using oyster shell as aggregate the most commonly occurring particle sizes form 2.5mm to 5mm.