• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.336-341
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• 1998

Steel fiber reinforced concrete(SFRC) is a composite material possessing many physical and mechanical properties which are distinct from unreinforced concrete. The use of steel fiber reinforcement to improve the flexural and tensile strengths, extensibility and toughness of ordinary cement concrete is well known at present, but reinforcement of polymer concrete with steel fibers has been hardly reported untill now. The objective of this study was to improve the properties of the polymer concrete by addition of steel fibers. In this paper steel fiber reinforced polymer concrete is prepared with various steel fiber contents and aspect ratio($\ell$ /d), and their mechanical properties were investigated experimentally.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.319-322
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• 1999

The adhesion properties of polymer cement mortars for cement concrete repair were evaluated with respect to polymer-cement ratios and the surface conditions of cement concrete substrate. Styrene-butadiene rubber (SBR) was used as an additive for polymer cement mortars. The adhesion strength of cement mortar was smaller than that of polymer cement mortar. The adhesion strengths to the dry surfaces of substrate were larger than those to the wet surfaces, indicating that the dryness of substrate increased the adhesion strength in repairing concrete structures.

• Steel and Composite Structures
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• v.31 no.4
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• pp.341-359
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• 2019

Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.330-335
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• 1998

This research was conducted to evaluate the adhesion in tension of the polymer mortars for cement concrete repair. Various polymer types, binder ratios, and wet/dry conditions of the surface were considered in this study. Styrene-butadiene rubber (SBR) and ethylen vinyl acetate (EVA) used for polymer cement mortars. Epoxy resin (EP), and unsaturated polyester resin (UP) were used for polymer mertars. Adhesion in tension for the dry condition of the substrate surface was higher than that for the wet condition of the substrate surface under the same binder ratio. Therefore, in repairing concrete, the dry surface condition was effective on adhesion.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.409-415
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• 2012

To recycle the steel slag as manufactured composite materials of polymer concretes, we used the atomizing method to make round aggregates from steel slag, which is treated as industrial wastes. A round rapid-cooled steel slag was used to replace fine aggregate (river sand) or coarse aggregate (crushed aggregate), depending on the grain size. To examine general physical properties of polymer concrete composites manufactured from rapid-cooled steel slag, the polymer concrete specimen with various proportions depending on the addition ratio of polymer binder and replacement ratio of rapid-cooled steel slag were manufactured. In the result of the tests, the mechanical strength of the specimen made by replacing the optimum amount of rapid-cooled steel slag increased notably (maximum compressive strength 117.1 MPa), and the use of polymer binder, which had the most impact on the production cost of polymer concrete composites, could be remarkably reduced. However, the mechanical strength of the specimen was markedly reduced in hot water resistance test of polymer concrete composite.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.565-572
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• 2004

The mechanical behavior of concrete-filled glass fiber reinforced polymer columns is affected by various factors including concrete strength, stiffness of tube, end confinement effect, and slenderness ratio of members. In this research the behavior of slender columns was examined both experimentally and analytically. Experimental works include 1) compression test with 30cm long glass fiber composite columns under different end confinement conditions, 2) uni-axial compression test for 7 slender columns, which have various slenderness ratios. Short-length stocky columns gave high strength and ductility revealing high confinement action of FRP tubes. The strength increment and strain change were examined under different end confinement conditions. With slender columns, failure strengths, confinement effects, and stress-strains relations were examined. Through analytical work, effective length was computed and it was compared with the amount of reduction in column strength, which is required to predict design strength with slender specimens. This study shows the feasibility of slender concrete-filled glass fiber reinforced polymer composite columns.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.695-698
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• 2004

Recently, the usage of polymer concrete mortar gathering an interest as a new construction material rapidly increases inside and outside of the country because it is an environment-friendly and endurable material. However, up to these days, the researches about the polymer composite have not been satisfactorily conducted. The polymer concrete is superior to the general cement materials in the properties of strength and durability while it is inferior in elastic modulus. Because that the members using the polymer concrete have therefore higher strength and ductility than the members of general cement concrete, an analysis equation of high-strength cement concrete can be referenced but it is not applied for the researches about the polymer concrete members. In this study, the flexural properties of T-shaped beam of the steel- and GFRP-reinforced polymer concrete are analyzed to examine the suggested analysis equation. Results of this experimental researches are to be used as the basic data in a structural design of the polymer concrete.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.380-385
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• 2014

Spherical atomizing reduction steel slag was prepared by atomizing technology using reduction steel slag (ladle furnace slag, LFS) generated from steel industry. In order to develop the mass-recycling technology of atomizing reduction steel slag, polymer concrete composite was prepared using spherical atomizing reduction steel slag instead of fine aggregate (river sand) and coarse aggregate (crushed aggregate), depending on the grain size. Different polymer concrete specimens were prepared with the various proportions of polymer binder and replacement ratios of atomizing reduction steel slag in order to investigate the characteristics of polymer concrete composite. Results showed that compressive strengths of polymer concrete specimens decreased with the increase of replacement ratios of atomizing reduction steel slag, but flexural strengths of the specimens showed a maximum strength at the 50% of replacement ratios of atomizing reduction steel slag. It was concluded that addition ratio of polymer binder, which affect greatly on the prime cost of production of polymer concrete, could be reduced by maximum 18.2 vol% because the workability of the polymer concrete was remarkably improved by using the atomizing reduction steel slag. However, further study is required because the mechanical strength of the specimen using atomizing reduction steel slag was greatly reduced in hot water resistance test.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.117-125
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• 2012

In recent years, polymer concrete based on polyester resin have been widely generalized and the research of polymer concrete have been actively pursued by the technical innovations. Polymer concrete is a composite consisting of aggregates and an organic resin binder that hardens by polymerization. Polymer concrete are stronger by a factor of three or more in compression, a factor of four to six in tension and flexural and a factor of two in impact when compared with portland cement concrete. In view of the growing use of polymer concrete, it is important to study the physical characteristics of the material, emphasizing the short term properties as well as long term mechanical behavior. If polymer concrete is to be used in flexural load-bearing application such as in beam, it is imperative to understand the deformation of the material under sustained loading conditions. This study is proposed to empirical and mechanical model of polymer concrete tension creep using long-term experimental results and mathematical development. The test results showed that proposed model has been used successfully to predict creep deformations at a stress level that was 20 percent of the ultimate strength and viscoelastic behavior of recycled-PET polymer concrete is linear of stress level up to 30 percent. It is expected that the present model allows more realistic evaluation of varying stresses in polymer concrete structures with a constant loading.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.828-835
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• 2000

In recent years, RC structures need reinforcement due to physical and chemical deterioration, reduction of serviceability and structural capacity. For reinforcement of RC structures, steel plate attachment, area increase and composite fiber sheet attachment methods are used, but there are some problems like weight increase, workability, quality control and fire resistance capacity. This study presents the effectiveness of flexural reinforcement of RC beams using composite rods that are inserted in high strength special purposed polymer mortar.