• KIEAE Journal
• /
• v.13 no.4
• /
• pp.103-112
• /
• 2013

The Federal Democratic Republic of Nepal(Nepal) is one of the poorest country in the world. People in Nepal are having lots of housing problems including the lack of housing provision. Even Habitat for Humanity Nepal (HfH_Nepal) has developed various programs to diffuse ecological housing, still there are many problems due to financial and technological shortage. The purpose of this study is to verify the effects of suggestion of performance improvement for HfH_Nepal eco house with introduction of the housing situation and efforts to provide sustainable housing by HfH_Nepal in Terai plain. Ideas on CGI sheet roof with poor insulation, double panel bamboo wall and adobe brick wall which can overcome structural and waterproof flaws of the thin single panel bamboo wall. The experiment result shows that both ideas adapted to adobe brick house reduces daily temperature range 50.8% and humidity adjust effect. For the effective provision of adobe brick house, compressive strength was tested for the bricks made with locally available fiber materials. Brick with jute displayed 41.1% betterment than plain brick with closest packing condition while coconut and straw showed 25.1% and 7.9% improvement respectively. Technical and economic problems brought up during the building and experiment process were listed and countermeasures established. This kinds of building prototype houses and experiments can improve the living conditions of people in developing countries with little supplement of resources. Furthermore, consideration of locally available and affordable material can help the social and ecological sustainability in the world.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.2
• /
• pp.311-317
• /
• 2018

The new asphalt surface reinforcement method (ASRM) is one of the preventive maintenance methods in asphalt concrete pavements. The adhesion performance of new ASRM satisfied the standard of non-slip pavement and bridge waterproofing materials. As a results of durability tests (as wheel load, rolling bottle and UV resistance test), the new ASRM showed sufficient resistance to traffic and environmental loads. The waterproof and chemical resistance tests of new ASRM were conducted to evaluate whether the pavement could be protected from water and chemicals and the performances of new ASRM were satisfactory. Furthermore, the new ASRM demonstrated some rejuvenation effects due to its toughness increases in recycled asphalt concrete mixture by 5% compared to the conventional hot mix asphalt mixture using reclaimed asphalt pavement. In conclusion, the new ASRM was evaluated to protect the asphalt concrete pavement and increase the lifetime.

• Tunnel and Underground Space
• /
• v.26 no.3
• /
• pp.212-219
• /
• 2016

The sprayable waterproofing membrane is installed between shotcrete to provide crack bridging and hence prevent flow of liquid water as a waterproofing system. Because of its material characteristics, the sprayable membrane can be constructed at more complex structure than sheet membrane. The main component of the sprayable waterproofing membrane is a polymer-based material, therefore, moisture can migrate through sprayable waterproofing membrane materials by capillary and vapor diffusion mechanisms. The moisture transport mechanisms can have an influence on the degree of saturation and may influence the pore pressure and risk of freeze-thaw damage on concrete linings and membrane. In this study, long-term hygrothermal behavior was simulated with considering moisture transport and long-term effects on saturation of tunnel linings. From the simulation, due to water absorption and vapor transport properties of sprayable membrane, change of relative humidity and water content in tunnel lining can be evaluated.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.10
• /
• pp.65-76
• /
• 2021

There is a possibility of cavities occurring inside and behind the lining of an aged tunnel structure. In most cases, it is not easy to check the cavity because it exists in a place where visual inspection is impossible. Recently, attempts have been made to evaluate the condition of the tunnel lining and the backfill materials using non-destructive tests such as Ground Penetrating Radar, and various related model tests and numerical analysis studies have been conducted. In this study, the GPR signal characteristics for tunnel lining model testing were analyzed using gprMax software, which was compared with model test results. The numerical model applied to the model test reasonably simulated the electromagnetic wave signal according to the change of the material such as tunnel lining and internal cavity. Using the verified GPR model, B-scan data for the development of the GPR signal analysis technique were obtained, which can evaluate the thickness of the tunnel lining, the presence of the cavity, the effect of the waterproof membrane, and the frequency band.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.3
• /
• pp.101-112
• /
• 2019

The grouting method is utilized to reinforce and waterproof poor grounds, enhance the bearing capacity of geo-structures damaged from differential settlement. The purpose of this research is to improve the compressive strength and degree of grout using reinforcing fibers and blast furnace slag powder. In this regard, this study has conducted uniaxial compression tests for the specimens with high ratios (higher than 50%) of blast furnace slag powder. The carbon fiber content was increased by 0, 0.5, and 1.0% to coMpare its compressive strength with that of aramid fiber. The uniaxial compressive strength increased with the increase of fiber content and the bridging activity by fiber in cement tended to increase uniaxial compressive strength. Based on the results, it was confirmed that the aramid fiber has a gel time of 14 seconds and the uniaxial compressive strength is more than 3 Mpa coMpared to carbon fiber.

• Composites Research
• /
• v.21 no.3
• /
• pp.1-8
• /
• 2008

The main objective of this study is to investigate the effect of salt water on the mechanical properties of a carbon-epoxy composite material. Specimens were made of a carbon-epoxy composite USN125 and tested under inplane tension and shear after 0, 0.5, 1, 2, 3, 6, 9, and 12 months immersion in 3.5% salt water. Waterproof painting and acceleration technique were not applied. The tensile strengths and moduli in fiber and matrix directions did not show any remarkable degradation until 12 months immersion. In contrast to the tensile properties, shear strength and modulus started to degrade from the early stage of the immersion time and gradually decreased to 36% and 46% of dry values, respectively, after 12 months immersion.

• Journal of Conservation Science
• /
• v.25 no.1
• /
• pp.49-60
• /
• 2009

Outdoor iron artefacts are easily corroded by salts, especially $Cl^-$ion, from environmental pollutants and acid rain because of their location, so that they need conservational treatments such as stabilization. However the conservation of outdoor iron artefacts are limited to be consolidated for the present and there are a few the studies for the desalinization. The general desalinization method is that objects are immersed in reagent such as alkaline corrosion inhibiting solutions targeting on buried iron artefacts, thus they are not available for outdoor iron artefacts. In this study, concerning those difficulties, the different desalting method is experimented that materials soaked in alkaline solutions attach to objects and they are packed by waterproof to avoid evaporation. This paper experiment burial iron artefacts at first in order to fine out an adaptable method for outdoor iron artefacts. The soaking materials are Korean traditional paper, gauze, cotton wipers, spill pads and the desalting regent is NaOH 0.1M. Additionally the exiting desalinization method which is to immerse objects in solution is performed to compare. The analyses are microscopes, SEM-EDS, X-ray diffraction, pH meter and Ion chromatography. The result is that spill pads show the best desalting effect out of other materials similar to immersing desalting method.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.553-561
• /
• 2020

Water-soluble rubber asphalt-based waterproofing material, which is one of the waterproofing materials for building structures, is mainly used indoors (toilet, kitchen, balcony, etc.). In general, asphalt-based materials are used for non-exposed installation, rather than as exposed type as they do not deviate from their usual basic black pigmentation, and water-soluble rubber asphalt-based coating waterproofing materials are basically limited to indoors because of their low physical properties. Accordingly, in order to improve the tensile and elongation properties, a silane coupling agent, an inorganic filler, and a processor oil w ere added to improve the physical properties, and accordingly, the basic physical properties of the outdoor coating waterproofing material quality standard were analyzed. As a result, the water-soluble rubber asphalt coating waterproofing material compared with the exposure quality standard showed a result that exceeded the basic physical property quality standard of silicone rubber in all items under test evaluation, but the tensile strength and tear strength of the first class of urethane rubber were chloroprene. It was found that the performance compared to the quality standards of rubber-based tear strength was about 34.2% to about 40.8%.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.6
• /
• pp.465-481
• /
• 2022

Rock grouting is important to improve the waterproof efficiency and mechanical strength of rock medium with joint for utilizing the underground rock space such as tunnel. The grouting materials typically has been used the cement materials, which represent Bingham fluid model. This model can express the relationship of viscosity and yield strength. In addition, it is dependent with elapsed time. The grouting injection performance can be deteriorated with an increase of viscosity and yield strength in the grouting process if the time dependence is ignored. Therefore, in this study, the characteristics of viscosity and yield strength were investigated according to water-cement ratio and time dependence in the laboratory test. Numerical simulation was carried out to investigate the grouting performance according to the time dependence of characteristics in terms of the viscosity model. Given the results, the grouting injected distance and cumulative grout volume were significantly decreased when the time dependence of grouting material was considered. This study, considering the characteristics according to the time dependence of viscosity and yield strength, will be meaningful to the design of grouting injection in field applications.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.1
• /
• pp.67-77
• /
• 2019

The grouting method is utilized to reinforce and waterproof poor grounds, enhance the bearing capacity of structures damaged resulting from settlement due to elevation and vibration or differential settlement, and for cutoff. The purpose of this research is to enhance the compressive strength of grout materials by using aramid fiber and develop a high-strength ground improvement method by using blast furnace slag powder. In this regard, this study has conducted a uniaxial compression test after checking the high charge (higher than 50%) of the ratio of blast furnace slag powder and cement at 100:0, 70:30 and 40:60%, adding the aramid mixture based on 0, 0.5 and 1.0% of the cement and furnace slag powder weight and creating sand gels based on surface oiling rate of 0.7 and 1.2%. For the environmental review evaluation, a heavy metal exudation test and a pH test measurement have been conducted. The experiment results showed that 1% increase of aramid fiber led to 1.3 times greater uniaxial compression intensity. As for the hexavalent chrome, a 30% increase in blast furnace slag powder led to approximately 50% decrease in heavy metal exudation. However, the pH test revealed that a 30% increase in blast furnace slag powder resulted in approximately 0.5 increase in pH. Further research on the pH part is needed in the future.