• Computers and Concrete
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• v.7 no.6
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• pp.497-510
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• 2010

For better estimation of elastic property of concrete composites, the effect of Interfacial Transition Zone (ITZ) has been found to be significant. Numerical concrete composites models have been introduced using Finite Element Method (FEM), where ITZ is modeled as a thin shell surrounding aggregate. Therefore, difficulties arise from the mesh generation. In this study, a numerical concrete composites model in 3D based on FEM and random unit cell method is proposed to calculate elastic modulus of concrete composites with ITZ. The validity of the model has been verified by comparing the calculated elastic modulus with those obtained from other analytical and numerical models.

• Journal of the Korea Institute of Building Construction
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• v.4 no.3
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• pp.93-100
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• 2004

In recent years, it has widely been studied on the light-weight composites for the purpose of the large space and thermal insulation of building structures. The purpose of this study is to evaluate the properties of light-weight composites made by binders as cement, resin and polymer cement slurry. The concrete composites are prepared with various conditions such as polymer-cement ratio, void-filling ratio, type of resin, filler content and light-weight aggregate content, tested for thermal conductivity. From the test results, the thermal conductivity of concrete composites with the binder of cement tends to decrease with increasing polymer-cement ratio, and to increase with increasing void-filling ratio. The thermal conductivity of concrete composites with the binder of resin are markedly affected by the light-weight aggregate content, type of resin and filler content. The composites made by polymer-modified concrete and polymer cement slurry have a good thermal insulation property. From the this study, we can recommend the proper mix proportions for thermal insulation Panel or concrete. Expecially. the thermal conductivity of concrete composites made by polyurethane resin is almost the same as that of the conventional expanded polystyrene resin.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.64-67
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• 2004

In recent years, the use of FRP composites to repair and strengthen existing reinforced concrete (RC) structures has been widely used. When the columns of existing RC structures are wrapped with FRP composites, the core concrete of such columns is confined not only by the FRP composites but also by the existing steel reinforcing ties (or spirals). Therefore, it is necessary to understand correctly the compressive response of concrete confined with both steel spirals and FRP composites in order to predict the behavior of such RC columns. This paper proposes a model to predict the compressive stress-strain curves of concrete confined with FRP and steel reinforcing ties.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.371-374
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• 2005

The research reported in this paper provides the test results of eleven reinforced concrete beams strengthened with FRP composites. Three parameters were considered in this investigation: the amount of FRP composites, the types of bonding schemes(continuous sheets or strips), and the material types of FRP composites (Carbon or Glass). The experimental results indicated that because the rupture strain of FRP composites was relatively higher that the yield strain of steel bars, the RC beams strengthened with FRP composites failed due to concrete crushing before the FRP composites arrived at its rupture strain. The compatibility-aided truss model showed reasonable agreement between the predicted and experimental shear stress-strain curves of the beams throughout the entire loading history.

• Journal of the Korea Institute of Building Construction
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• v.8 no.6
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• pp.131-137
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• 2008

In recent years, the light-weight aggregate has widely been used to reduce the weight of construction structures, and to achieve the thermal insulation of building structures. The purpose of this study is to evaluate the heat resistance of polymer concrete composites with light-weight aggregate made by binders as resin and cement with polymer dispersion. The light-weight polymer concrete composites are prepared with various conditions such as binder content, filler content, void-filling ratio, light-weight aggregate content and polymer-cement ratio, and tested for heat resistant test, and measured the weight reducing ratio, strengths and exhaustion content of gas such as CO, NO and $SO_2$. From the test results, the weight reducing ratio of light weight polymer concrete using UP binder after heat resistance test increase with an increase in the UP content irrespective of the filler content. The weight reducing ratio of polymer cement concrete is considerably smaller than that of UP concrete. In general, the strengths after heat resistance of polymer concrete composites are reduced about 40 to 65% compared with those before test. The exhausted quantity of CO, NO and $SO_2$ gases in polymer concrete composites is less than EPS(Expanded poly styrene). From the this study, it is confirmed that the many types gases discharge according to binder type of polymer concrete composites, its amount is controlled by selection of the binder type and mix proportions.

• Journal of the Korean GEO-environmental Society
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• v.8 no.2
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• pp.57-63
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• 2007

Coal combustion by-product (CCB) bottom ash, obtained from burning of pulverized coal, has physical properties which are similar to that of natural sand with particle sizes ranging from fine gravel to fine sand. Several studies have been completed to utilize pulverized coal combustion (PCC) bottom ash as a partial or full replacement of fine aggregate in cement concrete products. The objectives of this study were to develop air-entrained concrete composites using PCC bottom ash from burning of Illinois coal and to demonstrate the use of these composites on real-world projects. The results obtained show that the compressive, splitting-tensile, and flexural strengths of concrete composites is slightly lower than that of conventional concrete are early curing ages. However, after 60 days of curing, the strength of concrete composites is either equal to or slightly higher than that of an equivalent conventional concrete. The concrete composites showed lower resistance to chloride ion penetrability than that of an equivalent conventional concrete at early curing ages. However, after 28 days of curing, concrete composites showed better resistance to chloride ion penetrability compared to that of an equivalent conventional concrete.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.183-188
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• 1999

Due to many advantages of advanced composite materials, research on the application of composites to the construction industry is initiated. In this paper, fabrication methods efficient for infrastructures and application examples of each method are discussed. It also presents the structural characteristics of concrete filled glass fiber reinforced composite tubular member. Experimental results shows that strength and ductility of composite compression member is considerably increased due to concrete confinement action of composite surface.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.167-170
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• 2005

This paper summarizes the results of a series of numerical evaluations (Lee et al., 2004, 2005) on the performance of pre-cracked reinforced concrete (RC) beams coated with polymeric composites. It was intended to numerically show the superior characteristics of the polymeric composites for enhancing the strength and ductility of existing concrete structures. Further, the predicted load-carrying and energy absorbing capacities of the beams were compared with previous experiments to verify the predictive capability of implemented computational model.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.401-404
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• 2004

In recent years, the use of fiber reinforced polymer (FRP) composites to repair or strengthen existing reinforced concrete (RC) structures is increasing In order to evaluate the shear strengths of RC structures strengthened by FRP composites, it is needed to understand the shear failure modes of these structures. This paper presents a rational equation to distinguish the shear fail modes of RC structures strengthened by FRP composites using the compatibility aided truss models.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.647-652
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• 1997

Repair and rehabilitation of existing structures is becoming a major part of construction, both in the industrially developed and developing countries. Advanced high strength composites are being utilized more and more for these applications because they are much stronger than steel, non-corrosive, and light. The light weight reduces the construction cost and time sustantially. The fibers are normally made of aramid, carbon, or glass and the binders are typically epoxies or esters. One major disadvantage of these composites is the vulnerability to fire. In most instance, the temperature cannot exceed $300^{\cire}C$. Since carbon and glass can substain high temperatures, an inorganic polymer is being evaluated for use as a matrix. The matrix can sustain more than $1000^{\cire}C$. The results reported in this paper deal with the mechanical properties of carbon composites made with the inorganic polymer and the behavior strengthened reinforced concrete beams. The results indicate that the new matrix can be successfully utilized for a number of applications.