• Advances in materials Research
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• v.5 no.3
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• pp.171-179
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• 2016

Fusion and characterization of bisphenol-A diglycidyl ether based thermosetting polymer mortars containing an epoxy resin, Fly ash and Rock sand are presented here for the Experimental study. The specimens have been prepared by means of an innovative process, in mild conditions, of commercial epoxy resin, Fly ash and Rock sand based paste. In this way, thermosetting based hybrid mortars characterized by a different content of normalized Fly ash and Rock sand by a homogeneous dispersion of the resin have been obtained. Once hardened, these new composite materials show improved compressive strength and toughness in respect to both the Fly ash and the Rock sand pastes since the Resin provides a more cohesive microstructure, with a reduced amount of micro cracks. The micro structural characterization allows pointing out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars. A correlation between micro-structural features and mechanical properties of the mortar has also been studied.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.104-105
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• 2016

From the Industrial Revolution by past to the present, Carbon emission quantity increase rapidly around the globe. Depending on this status, Also global warming are accelerated rapidly, in order to solve this status, the Climatic Change Convention is held now on. So, On this study, Utilizing the BFS, HFA, DS that we get the basic data of the cementless paste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.160-161
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• 2017

In In this study, we measured the relative density and the compressive strength in order to select the appropriate W/B for the ultra-high strength concrete development. If W/B is lowered than the W/B of highest relative density, it was confirmed that the strength is lowered. However, if water is increased than the W/B, the relative density is decreased compressive strength was similar. The selection of the W/B of the lower than the highest relative density is not appropriate. Appropriate W/B is selected to be more than the maximum relative density of W/B. This was confirmed for TG-DTA.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.95-97
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• 2012

Recycled aggregate (RA) produced from demolished concrete waste can bring about several problems on concrete performance, when it is used as aggregate for new concrete. Because RA generally has lower quality than natural aggregate due to the residual cement paste attached on RA and various impurities. It is also very difficult to ensure that the quality of RA remains consistent, because generally RA is produced variously. Thus, in concrete recycling, it is extremely important to estimate the risk of the impurities which could affect performances of recycled aggregate concrete (RAC) focusing on the material flow of concrete waste and its recycling. This study suggests an evaluation result to expect the possibility of impurity mixing in RA production procedure. and suggests a risk evaluation model to expect the changes of RAC performances based on conventional data in Japan.

• KIEAE Journal
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• v.7 no.1
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• pp.73-80
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• 2007

This paper aims to develop the diffused reflection material in order to reduce the solar absorption coefficient, and to compare the thermal properties with the different roof structure system; one is using the diffused reflection material applied the upper side of the rigid sheet waterproof system and the other is using the conventional up-side down waterproof system on the roof. For this purpose two experimental test boxes were made of same iso-panel wall and floor with different roof system. The experiment was carried out under these process; measure the surface temperature exposed solar radiation of the variation of the reflection materials(cement paste, silica, galvanized steel and titanium dioxide(TiO2)), measure and analyze the variation of the temperature distribution of the each roof system and indoor air in order to evaluate the thermal properties according to the different roof system. The result shows clearly that using the titanium dioxide(TiO2) might be more effective to reduce the solar insolation.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.153-159
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• 1996

The concrete with continuous voids (No Fine Concrete ; NFC) is the new planting material which may be used for stabilizing the sandy slope of river or road sides. The components of NFC are mainly coarse aggregate and low alkali cement paste, so to speak fine aggregate is not used. This report shows the fundamental properties of NFC, such as continous void ratio, compressive strength, permeability. As experimental results we can get the good quality of NFC, that is about 28% continuous void ratio, about 120kg/$\textrm{cm}^2$ compressive strength and high flowable permeability. And also planting grass and garden portulaca on the concrete with continuous voids is resulted in success.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.32-33
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• 2016

In this work, pozzolanic activities of various waste materials were compared with those of well-known pozzolanic materials. Uncondensed and densified silica fume, two ASTM class F fly ashes with different calcium contents, and bentonite powder, ceramic powder obtained from wash basin, and waste glass wool, which can possibly possess pozzolanic property were chosen for comparison. Drop in electrical conductivity at 40℃ saturated lime solution was measured for each materials. The amount of Ca(OH)₂ decomposed from cement paste at 450~500℃ was also measured used to evaluate pozzolanic activity. The 28 day compressive strength were used to observe the mechanical property enhanced by various waste materials.

• Computers and Concrete
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• v.1 no.2
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• pp.131-150
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• 2004

We present in this work a coupled phenomenological chemo-mechanical model that represents the degradation of concrete-like materials. The chemical behaviour is described by the nowadays well known simplified calcium leaching approach. And the mechanical damage behaviour is described by a continuum damage model which involves the gradient of the damage quantity. The coupled nonlinear problem at hand is addressed within the context of the finite element method. For the equation governing the calcium dissolution-diffusion part of the problem, special care is taken to treat the highly nonlinear calcium conductivity and solid calcium functions. The algorithmic design is based on a Newton-type iterative scheme where use is made of a recently proposed relaxed linearization procedure. And for the equation governing the damage part of the problem, an augmented Lagrangian formulation is used to take into account the damage irreversibility constraint. Finally, numerical simulations are compared with experimental results on cement paste.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.1-4
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• 2005

This research is to present experimental materials model of high strength concrete for prediction of fire safety of structural members based on physical properties of materials during heating up to 800$^{circ}C$. The following conclusions are drawn from this study. First of all, between 100 to 200 $^{circ}C$, the physical models of concrete such as specific heat and thermal conductivity, show visible degradation, regardless of concrete strength. Second, between 300 to 600$^{circ}C$, the physical models of the 29MPa and 49MPa concrete show degradation continually at these temperatures. Finally, beyond 600$^{circ}C$, the physical models of 49MPa strength concrete show larger degradation than 29MPa strength concrete due to rise of pore pressure and melting of the interface between aggregate and cement paste.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.117-120
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• 2005

It is necessary for decrease of building waste to increase using of recycled aggregate. However, the quality of those recycled aggregates is not good enough. This study aim at the rise of the quality through abrasion test and researching the characteristic change of the test. The samples of recycled aggregates had been divided into 10 sorts by the amount of cement paste, and then the abrasion rate of those divided aggregates has been figured out through this experiment. The result of this experiment shows that the quality of the recycled aggregates has been improved.