• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.97-104
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• 2018

In recent years, more than 5,000 tons of sargassum honeri have been infested in the southern coast and the coast of Jeju Island, causing serious damage to the farms and fisheries, and environmental problems. The alginate contained in the sargassum honeri is a natural polymeric substance mainly used for medicines and foods. However, since there is no way to utilize it in large quantities, a study was carried out to utilize bio polymer obtained from sargassum honeri in producing polymer mortar for repairing deteriorated infrastructures. From the tests of setting time, it was found that the L0BP12 mixture containing 12% of bio polymer increased the setting time by 20% as compared with the L12BP0 mixture using only synthetic polymer. From the tests of water absorbtion, the LOBP12 combination decreased by 0.36% compared to Plain-URHC using ultra rapid hardening cement. This indicated that the watertightness of the mortar was increased by the incorporation of the bio polymer. In the compressive and flexural strength tests, the strength decreased as the amount of bio polymer increased. The incorporation rate of the maximum bio polymer satisfying the KS F 4042 standard was determined to be 12%. In addition, the bond strength of the mortar produced with biopolymer was higher than that of Plain-URHC specimens, and it was confirmed that incorporation of bio polymer improves bond strength of mortar.

• Journal of the Korea Institute of Building Construction
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• v.11 no.2
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• pp.127-135
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• 2011

In this study, the engineering characteristics of outer wall insulation panels according to type of insulation materials, their combination, and the contents of insulation materials were tested. Vermiculate, ceramic bead, perlite and expanded polystyrene were used as insulation materials. Flexural strength and thermal conductivity depending on the insulation materials used were measured. It was found that the flow of fresh mortar significantly decreased with an increase in the contents of insulation materials. In terms of the effect of insulation materials on thermal conductivity, an increase in insulation materials resulted in a decrease of thermal conductivity. In particular, PL and EPS, when used together, have lower thermal conductivity than other materials. Regarding the flexural strength of the hardened mortar, the strength showed a tendency to gradually decrease according to the increase in contents of insulation materials, compared to that of the plain mortar. In terms of the flexural strength depending on various types of insulation materials and its combination, it was found that the flexural strength of cement mortar containing 3% of vermiculate(V)+ceramic bead(CB)+perlite(PL) was the highest among the specimens tested.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.419-427
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• 2018

The purpose of this study is to recycle steel slag generated from the iron producing process and to use steel slag as a construction material which is currently landfilled Steel slag is subjected to aging treatment due to the problem of expansion and collapse when it reacts with water. The Slag Atomizing Technology (SAT) method developed to solve these problems of expanding collapse of steel slag. In this study, experimental study on the emergency repair mortar using the reducing slag, electric arc furnace slag and silicon manganese slag manufactured by the SAT method is Reduced slag was shown an accelerated hydration when it was replaced with rapidly-setting cement, and the rate of substitution was equivalent to 15%. It is shown that the electric furnace oxide slag is equivalent to 100% of the natural aggregate, and it can be replaced by 15-30% when the silicon manganic slag is substituted for the electric furnace oxide slag. With the above formulation, it was possible to design the rapidly repair mortar for road use. These recycling slags can contribute on achieving sustainability of construction industry by reducing the use of cement and natural aggregates and by reducing the generation of carbon dioxide and recycling waste slag.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.1
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• pp.37-44
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• 2011

The maintenance works for brick-structured buildings are a new field in Korea, and practical cases are yet inadequate so that such works may cause adverse effects of damaging the buildings after all. Therefore, this study has extracted a preservation technology believed to be most desirable in minimizing the damage to the original state of the buildings and preserving the value as the cultural assets through maintenance work details from 1986 to 2010 regarding brick-structured buildings designated as cultural properties. Firstly, a brick replacement method of using the brick used at the time of construction is efficient in replacement and repair of brick material for preserving value of cultural assets and minimizing damage of the original form. Secondly, use of lime mortar through material analysis is effective in repair of masonry joint and mortar but it is not used often due to high experimental cost. Finally, reinforcement of structure using a form for a building with severe damage is most efficient when considering additional problems. However, damage on the original form of a building can be minimized and value of a building can be preserved only when consideration on sufficient case analysis, materials to be used, and conditions of a building is supported.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.279-288
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• 2003

This study is the development of method on repairing concrete structure for progressing the durability of reinforced concrete. This method is wet spray method which compress and conduct mortar pre-mixed with polymer powder to hose by high pressure pump and spray it on the section of concrete structure through nozzle made specially. Characters of this method are that materials are selected with the sort of structure and the cause of deterioration and macro pores are removed in repaired section by conducting with high pressure and spraying with high velocity for progressing the durability of concrete structure. This study has carried out that the minimum capacity of rebound was measured with various condition and physical properties of sample made by spray method were estimated in comparing with sample made by previous hand method. Also, properties of long-term have carried out after this method was applied on site. According to experimental study, the capacity of rebound showed below 5% and physical properties of sample made by spray method were superior to that of sample made by hand method and physical and durable properties of long-term showed excellence.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.210-217
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• 2023

Various performances of ultra-high performance concrete (UHPC) applied with microplastics and expanded polystyrene (EPS) beads were evaluated. CompressIve and flexural strength, performance after ignition, flow-down in fresh state, and effective bond strength were evaluated. Designed weight of the cement panel with these mixtures was calculated based on the flexural strength. As a result of the experiments, it was confirmed that the EPS could reduce the density of UHPC with largest range. By maximum addition of EPS beeds, the density of UHPC decreased to 1300 kg/m³, and the compressive and flexural strengths for this mixtures were in ranges of 20-30 MPa and 15-20 MPa, respectively. On the other hand, lightest cement panel could be designed with UHPC having a density ranges about 2.0 g/cm³.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.519-525
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• 2024

In this paper, a study on the physical properties of mortar applying 3D Textile was conducted to compensate for the shortcomings of the existing concrete surface repair and reinforcement method. In the tests conducted to analyze the physical properties, compressive strength, flexural strength, and dynamic modulus measurement tests were conducted. As a result of the compressive strength test, as the number of surfaces to which the stereoscopic fiber was applied increased, the amount of displacement and strength reduction rate increased, and the flexural strength also increased as the number of surfaces to which the stereoscopic fiber was applied increased. In addition, it was confirmed that the use of stereoscopic fibers tended to decrease the dynamic modulus of elasticity. This result is a characteristic of the application of stereoscopic fibers, and it caused a decrease in compressive strength due to a decrease in the mortar content of the part to which the stereoscopic fib er was applied, and the high tensile force of the stereoscopic fiber is believed to have affected the increase in flexural strength.

• Composites Research
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• v.18 no.4
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• pp.66-74
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• 2005

This paper reports new repair and strengthening mathod using improved material. This mathod have two type according to covering thickness of reinforcement. One type is near surface mounted FRP rod. Anther type is overay. Fiber Reinforced Plastic (FRP) materials has become very popular in recent years. FRP material used to rehabilitate many types of structures with superior characteristics such as high strength and stiffness and corrosion resistance. This strengthening mathod were used FRP rod which have better bond and shear strangth than current FRP rod. Development of FRP rod due to 3-D winding system. In addition, Ductile hybrid FRP has a certain plastic deformation and an elongation greater than 3% at maximum load is usually required for steel reinforcement in concrete structures. Moerover this mathod can be effective repair of base concrete by sprayed polymer mortar.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.637-643
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• 2005

Reinforced concrete beams or slabs are often strengthened or repaired using polymer modified cement concrete Stresses can develop in the structure by ambient temperature changes because thermal coefficients of the repair material and the existing concrete are typically different. Especially, shear stress often causes debonding of the interface. In this study, a rational procedure was developed where anchors can be designed in strengthened or repaired concrete members to prevent debonding at the interface. The current design procedure considers thicknesses and elastic moduli of the repair material and existing concrete, ambient temperature change, length, and beam-vs.-slab action. The procedure is also applicable to stresses developed by differential drying shrinkage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.1 no.1
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• pp.107-112
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• 1997

A series of reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. The key parameters for this study were the size and location of the patch, and the repair materials, including polymer, polymer-cementitious and cementitious materials. The repaired specimens failed by a typical flexural mode with minor interfacial bond failure. Beams repaired with polymer, polymer-cementitious and cementitious materials recover 100%, 91%, and 97% of the flexural strength respectively, while beams with cement mortar lose approximately 30% of the strength. Compared with the pressure injection techniques the specimens repaired with patching techniques show low flexural strength, with significant interfacial bond failure. Location and size of the repaired part do not affect the recovering performance. Interfacial behavior between repair and strengthening materials is the major influencing factor for the composite structures.