• Computers and Concrete
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• v.22 no.4
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• pp.407-417
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• 2018

Over the past three decades, self-compacting concrete (SCC), which is characterized by its superior rheological properties, has been gradually used in construction industry. It is now recognized that the application of SCC using supplementary cementitious materials (SCM) is highly attractive and promising technology reducing the environmental impact of the construction industry and reducing the higher materials costs. This paper presents an experimental study that investigated the mechanical and durability properties of SCCs manufactured with blended binders including fly ash, slag, and micro-silica. A total of 8 batches of SCCs were manufactured. As series of tests were conducted to establish the rheological properties, compressive strength, and durability properties including the water absorption, water permeability, rapid chloride permeability and initial surface absorption of the SCCs. The influences of the SCC strength grade, blended types and content on the properties of the SCCs are investigated. Unified reactive indices are proposed based on the mix proportion and the chemical composition of the corresponding binders are used to assess the compressive strength and strength development of the SCCs. The results also indicate the differences in the underlying mechanisms to drive the durability properties of the SCC at the different strength grades.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.86.2-86.2
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• 2010

In order to improve polymer electrolyte membrane fuel cell (PEMFC) durability, the durability of membrane electrode assemblies (MEA), in which the electrochemical reactions actually occur, is one of the vital issues. Many articles have dealt with catalyst layer degradation of the durability-related factors on MEAs in relation to loss of catalyst surface area caused by agglomeration, dissolution, migration, formation of metal complexes and oxides, and/or instability of the carbon support. Degradation of catalyst layer during long-term operation includes cracking or delamination of the layer which result either from change in the catalyst microstructure or loss of electronic or ionic contact with the active surface, can result in apparent activity loss in the catalyst layer. Membrane degradation of the durability-related factors on MEAs can be caused by mechanical or thermal stress resulting in formation of pinholes and tears and/or by chemical attack of hydrogen peroxide radicals formed during the electrochemical reactions. All of these effects, the mechanical damage of membrane and degradation of catalyst layers are more facilitated by uneven stress or improper MEA fabrication process. In order to improve the PEMFC durability, therefore, it is most important to minimize the uneven stress or improper MEA fabrication process in the course of the fabrication of MEA. We analyzed the effects of the MEA fabrication condition on the PEMFC durability with MEA produced using CCM (catalyst coated membrane) method. This paper also investigated the effects of MEA fabrication condition on the PEMFC durability by adding additional treatment process, hot pressing and pressing, on the MEA produced using CCM method.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.451-462
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• 2017

Physical weathering caused by external forces and chemical weathering caused by the decomposition or alteration of constituent materials are the two factors that dominate the mechanical properties of rocks. In this study, a field investigation was undertaken to identify the physical and chemical weathering characteristics of the biotite granite and granitic weathered soils in Gyeongju, South Korea. Samples were collected according to their grade of weathering and subjected to modal analysis, XRD analysis, XRF analysis, physical property tests, particle size distribution tests, and slake durability tests. Modal and XRD analysis identified these rocks as biotite granite; secondary alteration minerals were not observed. Physical property tests and particle size distribution analyses indicate an average porosity of 41.28% and a sand content of > 90 wt.%. These values are somewhat higher than those of granites in general. The results of the slake durability test and XRF analyses show that the physical and chemical weathering indices of the samples vary with the degree of weathering.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.558-563
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• 2014

To study the effects of fabrication methods on the performance and durability of polymer electrolyte membrane fuel cells (PEMFCs), membrane-electrode assemblies (MEAs) were fabricated using a Dr blade method, a spray method, screen print method and screen print + spray method. The performance of single cells assembled with the prepared MEAs were initially measured and compared. Electrode accelerated stress testing (AST) involving a potentiostatic step-wave with 10 s at 0.6 V followed by 30 s at 0.9 V was applied to test durability of MEAs. Before and after 6,000cycles of the AST, I-V curves, impedance spectra, cyclic voltammograms, linear sweep voltammetry (LSV) and transmission electron microscope (TEM) were measured. Under the operating conditions, the Dr Blde MEA exhibited the highest initial performance. After electrode accelerated stress testing, screen print + spray MEA showed lowest degradation rate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.247-252
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• 2009

The LMC method of construction which have application to the road bridge is being considered the least relative importance about the watertight performance, because it focused on the durability of concrete. However, The LMC which is being expanded scope of application to the method of construction has grown importance about the watertight performance on the usability and maintenance side as well as durability. In this study, The latex concrete of two types which are different from mingled-ratio of the latex made a comparison to the compressive strength, watertight performance, dynamic wheel load resistance performance and confirmed what it has resistibility about chemical action through the chemical resistance test. The initial strength and watertight performance showed that were tendency the downward at 14 days. However, The long-term strength after 28 days showed that it has firm performance. In consequence, The initial curing of latex concrete is required to scrupulous care and attention at the site application. As a chemical resistance test result, The specimen that is steeped in sulphuric acid solution of 2% discovered the delamination phenomenon. However, it was confirmed that delamination phenomenon don't have an effect on the compressive strength. Moreover, As a dynamic wheel load resistance test result, The latex concrete was concluded to confirming the durability and running stability, because it had hardly any thickness reduction of latex concrete surface about dynamic wheel load and rarely found crack and delamination.

• KIEAE Journal
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• v.8 no.5
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• pp.55-60
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• 2008

The purpose of this study is to increase the use of Hwangto and examine the strength according to what it is compounded with. Hwangto-concrete containing Hwanto without cement nor organic chemical products were compared to the traditional cement concrete through some durability experiments. We expect to gain more knowledge on the potentials of Hwangto-concrete as an architectural source. 1) As Hwangto binder amount rises, the value of slump increases too. The reason is that the increase of the quantity of cement causes the increase of the amount of material and the decrease of the amount of aggregate. 2) When the mixed component into Hwangto-concrete remains at 2%, the compress strength is generally dispersed high along the per unit fission, in case the amount of which is at $400(g/m^3)$. The highest compress strength is 39MPa. It means that it can be applied to common structures and we need to conduct a basic property test to ensure the strength and fluidness. 3) Hwangto-concrete is expected to be highly used in the ocean structure and chemical industry because it has better resistance to sulfuric acid and to hydrochloric acid than the cement-concrete has. The result of this study is as follows. It is expected that Hwangto-concrete will be widely applied and further research on its durability and tests for its basic substantial characteristics based on future component added to it.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.943-948
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• 2013

In this study, the characteristics of polymer-modified mortar which include UM resin, eco-friendly resin, was studied for improving the durability of concrete. UM and cement mortar were mixed with a certain percentage. Eco-friendly UM resin polymer-modified mortar was evaluated by compressive strength, splitting tensile strength, flexural strength, water absorption and chemical resistance experiments. The characteristics of eco-friendly UM resin polymer-modified mortar were evaluated by experiments. Performance of compressive strength and splitting tensile strength were decreasing. On the other hand, performance of flexural strength, water absorption and chemical resistance were increasing. Eco-friendly UM resin polymer-modified mortar reinforced concrete durability performance is excellent.

• Geotechnical Engineering
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• v.12 no.2
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• pp.115-132
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• 1996

Several soil improvement methods are applied to stabilize soft ground. But, their improvement effects are known to be reduced in view of strength and durability under poor conditions such as marine clay and the ground with the flow of groundwater. The soil improvement method is generally classified as mixing(high pressure) type and injection type, and in this study, for successflll'applications of gelling methods, first in case that mixing method with cement is applied to marine clay, the causes of strength inferiority of treated soil are analyzed, and the effectiveness of improvement is studied, second in case that injection method with water-glass chemical grouts is applied to the ground with the flow of groundwater, soil improvement effects and durability of grouted soil are studied.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.97-100
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• 2005

Recently sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. In this study, to prevent biochemical corrosion of the sewer concrete, antibiotics which prevent the growth of sulfur-oxidizing bacteria were developed and antimicrobial performance of it was investigated. After that, to consider applicability of antibiotics to concrete, durability such as resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic and complex antibiotics were investigated. As a result of this study, it was proved that the antimicrobial performance of antibiotics was available. Also resistance to carbonation, salt damage and chemical attack of concrete covered with inorganic antibiotics was little improved but, in case of complex antibiotics, was remarkably improved. Moisture content of concrete, as a application condition of antibiotics in whole case, have little effect on performance but covering times of antibiotics have effect on performance only in case of complex antibiotics.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.107-112
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• 2008

A study on the enhancement of environmental durability of EPDM rubber materials for the aerator membrane was performed using a butyl rubber as a modifier. A conventional EPDM rubber formulation was evaluated as having about 26.0 wt% or more oil content from the chloroform immersion test. These oils would be gradually and continuously deleted from the aerator membrane when directly exposed to a waste-water or chemically corrosive fluids, making the membrane less flexible and the performance worse. To improve this, a butyl rubber (IIR) was utilized as the modifier for a low-ENB type of EPDM rubber formulation with low-oil content. The environmental durability of the IIR-modified EPDM rubber material was expected to be greatly enhanced compared to the conventional one. However, the mechanical and performance properties such as elongation, tensile strength, and air bubble size, etc. were still maintained as good as in the conventional one. Furthermore, TGA analysis of the IIR-modified EPDM material showed that there would be partially compatible between IIR and EPDM. It also showed that the initial degradation temperature of the IIR-modified EPDM could be somewhat increased, exhibiting the enhanced compatibility among the components and, thereby, more enhanced environmental durability.