• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.350-355
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• 1998

Preplaced aggregate concrete in the building fields has recently been used in the partial repair works for damaged reinforced concrete structures, and polymer-modified mortars have been employed as grouting mortars for the preplaced aggregate concrete. The objective of this study is to clear the properties of polymer-modified grouting mortars. Polymer-modified mortars using a polystyrene acrylic(St/Ac) emulsion as grouting mortars for preplaced aggregate concrete are prepared with various mix proportions, and tested for flexural and compressive strengths, adhesion in tension. The flexural strength of emulsion-modified grouting mortars does not give much variation with increasing fly ash replacement for cement and sand-binder ratio. With increasing polymer-binder ratio, the flexural strength and adhesion in tension of St/Ac emulsion-modified grouting mortars increases, become nearly constant or reaches a maximum at a polymer-binder ratio of 5%. From the test results, St/Ac emulsion-modified grouting mortar with a polymer-binder ratio of 5%, a fly ash replacement of 10% for cement and sand-binder ratio of 1.0 is recommended as a grouting mortar for preplaced aggregate concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.89-92
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• 1999

The purpose of this study is to evaluate the capability to use with cement admixture materials because Paper Sludge Ash consists of Si, Ca and Al which are chief content in Pozzolan. For the derivation of Pozzolanic reaction in Paper Sludge Ash, it is measured compressive strength on cement mortar which is replaced mixing of Paper Sludge Ash and inorganic admixture ; ie, gypsum, lime and slaked lime, regularly. In the result of test, the strength decrease remarkably when cement is only replaced with Paper Sludge Ash, but the strength is almost equal when cement is replaced with Paper Sludge Ash is mixed with inorganic admixture material in proportions of 5~15%. Consequently, It is possible to use Paper Sluge Ash with admixture materials of cement.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.31-34
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• 1989

In order to discuss the engineering properties of carbon fiber reinforced cement composites with silica fume and silica powder, experimental studies in the CFRC were carried out. The types of fiber used which are in CFRC are PAN-based carbon fiber and Pitch-based carbon fiber. To examine the effects of types, lengths, contents of carbon fiber and matrices, their properties of fresh and fardened CFRC were tested. According to the test results, the process technology of light-weight CFRC is developed and their potimum mix proportions are successfully proposed. Also, it can be concluded that the reinforcement of carbon fiber is considerably effective in improving tensile strenghth, flexural strength, toughness and loss of shrinkage of CFRC compared with conventional mortar.

• Magazine of the Korea Concrete Institute
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• v.1 no.1
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• pp.95-104
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• 1989

In order to discuss the engineering properties of carbon fiber reinforced cement composites with silica fume and silica powder, experimental studies on the CFRC were carried out. The types of fiber used which are in CFRC are PAN-based carbon fiber and Pitch-based carbon fiber. To examine the effects of types, Lengths, contents of carbon fibers and matrices, their properties of fresh and hardened CFRC were tested: According to the test results, the process technology of lightweight CFRC is developed and their optimum mix proportions are successfully proposed. Also, it can be conclueded that the reinforcement of carbon fiber is considerably effective in improving tensile strength, flexural strength, toughness and loss of shrinkage of CFRC compared with conventional mortar.

• International Journal of Concrete Structures and Materials
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• v.10 no.sup3
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• pp.65-74
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• 2016

During concrete pumping, the migration and redistribution of particles occur in a pipe and the lubrication layer that forms between the bulk concrete and the pipe wall is the governing factor determining the flow behavior. In order to identify flow behavior of pumping, in this study, the viscoelastic properties related to the microstructural behavior of a flocculated suspension were examined by using dynamic oscillatory measurements. Cement paste is assumed to be a constituent material of the lubrication layer and ten cases of mixing design are employed by changing the proportions of mineral admixtures. The relationship between the yield stress obtained from the steady shear test and the dynamic modulus resulted from the oscillatory shear measurement was derived and the implications of the correlation are discussed. Moreover, based on the investigation of the viscoelastic properties with oscillatory measurements, the initial behavior of pumped concrete was analyzed systematically.

• Economic and Environmental Geology
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• v.33 no.2
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• pp.139-146
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• 2000

Development of an effective liner by utilization of the tailings frm the Imcheon mine and polymer has been tried. The tailings piled in the Imcheon mine, whose true specific gravity is about 2.86, are composed mainly of quartz, alkali-feldspar, muscovite and pyrite, and mostly (93.7% in volume) coarser than sand grain size (50${\mu}{\textrm}{m}$). Strength, leaching and permeability tests have been performed on the test specimens of polymer concrete manufactured with various mixing proportions of tailings, unsaturated polyester resins(UPR), calcium carbonates, stone powder sludges and granite soils. Polymer concrete specimens with stone powder sludges or granite soils as fillers and aggregates indicate 2.5 to 3 fold higher flexural and compressive strengths and lower permeabilities than those with calcium carbonates, which shows their usability as a waterproof liner. Also, the polymer concrete liner with stone powder sludge fillers is more advisable in aspects of utilization of waste sludges than that with other fillers.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.359-362
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• 2005

This study was performed to know the properties and estimation of field application of concrete(Bluecon) using fluosilicate salt based admixture made from by-product during phosphoric acid manufacturing process. Mix proportions for experiment were modulated at 0.45 of water-binder ratio and $0.5-2.0\%$ of adding ratio of fluosilicate salt based inorganic compound. Evaluation for Field application of concrete was carried out batch plant test at remicon factory and building construction. According to results. it was found that slump of concrete(Bluecon) using fluosilicate salt based admixture is higher about 10 to 20 mm than plain concrete, and air content is similar to each other. And the water permeability and crack of bluecon is lower than that of plain concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.379-382
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• 2005

Ocher block has started to be studied recently as a new environment friendly alternative building material. This article investigates the use of Rice Husk Ask (RHA) as an additive to improve properties of the ocher block. Ocher mixtures incorporating various proportions of RHA were compared. Compressive strength at various ages of these ocher blocks was evaluated ad the resistance to wet environment was also examined. These test result help to determine the effect of RHA on such properties of the ocher block as compaction, mix proportion, compressive strength and water absorption indexes. Based on these results, the new alternative building material and low cost construction techniques might be developed through more intensive research efforts.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.577-580
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• 2006

As this study is to estimate resistance of cement mortars using crushed sand under chemical attacks. Besides tests have been carried out with cement mortars by river sand and crushed sand by fine sand, cement mortars mix various proportions of silica fume and fly ash(up to 15% and 50% by weight for cement) were prepared and immersed in pure water, sodium sulfate solution, magnesium sulfate solution, seawater for 28days, 60days, 90days and 180days. Test on the change in the weight and compressive strength of cement mortars according to the duration of immersion time and the content of silica fume and fly ash was performed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.41-44
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• 2006

Recently, single shell lining method of construction is studied by economical method of construction to make use of high-performance shotcrete of permanent shotcrete lining concept in the UStA, Europe, Japan etc. High-performance shotcrete use is essential as permanent support that single shell lining method of construction has two functions of lining and support to shotcrete. In this research, optimum accelerator amount was decided after setting time test using alkai-free and cement mineral accelerator. Also replacement ratio of silica fume and fly-ash was determined.