• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.741-750
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• 2004

Air voids in hardened concrete have an important influence on concrete durability such as freeze-thaw resistance, surface scaling resistance, and water permeability, and they have been characterized by spacing factor Linear traverse and point count methods in ASTM standard have been used in estimating an air void system in hardened concrete. However, these methods require lots of time and efforts, further they are not repeatable. Image analysis method could be utilized In estimating an air void systems in hardened concrete with a developments of microscope, digital camera and computer program. The purpose of this study was to develope image analysis method and provide a guideline by comparing the results from ASTM method and image analysis method. The concerns were at air void content and diameter distribution, air voids system as well as spacing factors. The experimental variables included air content by air entrained agent (0, 0.01, $0.03\%$) and depth of specimen (top, middle, bottom). The result showed that it was possible to calculate spacing factor using image analysis technique, as well as air content, air diameter distribution, and air structure. This study also contributed in developing an reasonable and repeatable image analysis method.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.67-79
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• 1996

Clay soils typically have low hydraulic conductivities in the presence of high polarity pore fluid, such as water. Low polarity fluids, such as hydrocarbon fuels and halogenated organic solvents, typically cannot migrate into clay pores because they cannot displace the pore water. Oxygenated additives in gasoline, such as alcohols and methyl-tert-butyl ether, are increasingly used to control air pollution emissions. These relatively polar and highly water-soluble compounds may facilitate displacement of pore water and enhance migration of fuels and solvents through clay-rich soil strata. In the reported research, the migration of gasoline-alcohol fuel mixtures (gasohol) through consolidated clay was examined. Prepared kaolinite clay samples were consolidated from slurry, and various combinations of gasoline, alcohol, and water were applied to the clays under 152 Pa gauge pressure. Movement of the fluids into the clay samples was monitored by measur ing displaced pore fluid and by magnetic resonance imaging of the samples. The structures of selected samples were examined using environmental scanning electron microscopy. Results of the research suggest that alcohol added to hydrocarbon fuels can enhance migration through some clays significantly. Gasoline did not migrate appreciably into water saturated clay, even after 14 days under pressure. The gasohol mixture migrated readily into the clay in only 20 minutes. Increased hydraulic conductivity of the clay in the presence of gasohol is hypothesized to be due to the collapse of the clays pore structure when ethanol is present, creating larger pores. Increasing pore diameter decreases the capillary pressure needed for the gasohol to replace water and allows gasohol to migrate through the clay.

• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.15-23
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• 1998

This experiment did comparison and analysis that protected soil particle migration have affect on function of the filter and therefore fall function of the filter. Results obtained are as follows: 1.High water head makes to be much movement of fine sand and out flow of particle to the outside. The filter have large opening size that reached stability an early stage, but much fine sand is washed away. If the velocity turns fast and becomes small, blocking phenomenon is remarkable nearby the filter-sand interface. 2. The movement of fine sand that effect on function of filter depend on opening size and change of water head. Under the same condition, USCE filter and USSPL filter is reached earlier than other filter that is stability of stage, because it's opening size is large. 3. Residual quantity of fine sand migration was largly come out in order of USSPL, USCE, USBR, Newton & Hurley, Bertram filter. 4. The time required to stability of flow was taken less in order of Bertram, Newton & Hurley, USBR, USSPL, USCE filter and coefficient of permeability was highly come out in order of USBR, Bertram, Newton & Hurley, USSPL, USCE filter. 5. It proved that USCE and USSPL is suitable for the filter criteria.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1581-1587
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• 2014

Two-lalyered quiet asphalt pavements are well known for their noise reduction capabilities compared to the conventional ones. This study was conducted to analyze the economic effects on two-layered quiet asphalt pavement rather than on one-layered. Noise prediction was performed on the data surveyed from the two-layered quiet asphalt pavement. In addition, the economic analysis was executed considering cost benefits using the noise prediction result. The permeability test was also investigated to evaluate the clogging recovery of two-layered quiet asphalt pavement. Analysis results revealed that the construction cost of two-layered quiet asphalt pavements was cheaper than that of the conventional soundproof walls. The two-layered quiet asphalt pavement with simulated clogging conditions was satisfied the permeability requirements of the permeable asphalt pavements. The permeability test results showed that the permeable time was recorded as 6.77 seconds for one cycle of cleaning job with 400 mL of water.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• Journal of the Society of Disaster Information
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• v.9 no.1
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• pp.56-64
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• 2013

The study examines the quiet pavement using fine-size aggregates and warm-mix technique to reduce traffic noise. In order to evaluate the quality of pavement, mix design and laboratory tests were carried out. Test results showed that using 10mm aggregates can reduce the cantabro loss compared with 13mm aggregates due to increase contact area between aggregates. Mixing and compaction temperatures of warm mix quiet pavement should be determined by gyratory compactor test because it is used high viscosity asphalt binder. Using warm-mix additive could reduce compaction temperature by about $15^{\circ}C$. Noise measurement and permeability tests were conducted at the test road for evaluation of the field performance. All of quiet pavements meet the standard of permeability and have sufficient porosity. Noise reduction of the quiet pavement using fine-size aggregates is more effective than that using 13mm aggregates. In particular, the effect of noise reduction was noticeable at low speeds.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.15-20
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• 2009

Marine concrete structure is exposed to salt injury and deteriorated by steel corrosion due to chloride ions diffusion. It, therefore, is very important to estimate the chloride diffusivity in concrete. In this paper the compressive strength and permeable pore volume of concrete are measured and the diffusion coefficient and penetration depth of chloride ions in concrete were investigated to estimate the chloride diffusivity efficiently. To correlate these results each other, regression analysis was done. The results showed a good linear relation between chloride diffusivity and the fundamental properties of concrete and the chloride diffusivity of concrete with water-cement ratios of $40%{\sim}60%$ were about $2.5{\sim}6.6{\times}10^{-12}m^2/s$.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.117-128
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• 2016

Chemical reaction tests were performed to assess the properties of hardened specimens of cement pastes (KS-1 Portland and Class G) exposed to supercritical CO₂ for 1, 10, and 100 days. After exposure, the samples' measured permeability and strength were compared with values measured for pristine samples. The pristine cements had permeabilities of 0.009~0.025 mD, which increased by one order of magnitude after 100 days of exposure (to 0.11~0.29 mD). The enhancement of permeability is attributed to the stress release experienced by the samples after removal from the pressure vessel after exposure. Despite its enhancement, the measured permeability mostly remained lower than the API (American Petroleum Institute) recommended maximum value of 0.2 mD. The degradation of the cement samples due to exposure to supercritical CO₂ led to a layer of altered material advancing inwards from the sample edges. The Vickers hardness in the altered zone was much higher than that in the unaltered zone, possibly owing to the increase in density and the decrease in porosity due to the carbonation that occurred in the altered zone. Hardness close to the edge within the altered zone was found to have decreased significantly, which is attributed to the conversion of C-S-H into less-strong amorphous silica.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.160-167
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• 2017

The purpose of this study is to identify the possibility of developing the 100% Recycled-resources Absorbent-Pervious Alkali-activated Blocks using both the alkalli-binder and the recycled aggregate. In addition, It established a test method such as Void ratio, compressive strength, coefficient permeability, absorption, and evaporation. As a result, an alkali-activated using recycled aggregate block was able to manufacture an 24 MPa class absorbent-pervious blocks with a liquid type sodium silicate and early high temperature curing. In this case, water-holding capacity, absorption and relative absorption were more effective than the natural aggregates. In conclusion, Absorbent-pervious alkali-activated Block Using recycled aggregate has a surface temperature reducing effect of approximately 10 % compared to ordinary concrete block.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.24-29
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• 2018

The properties of concrete with addition of microgel - containing hydrogel support were investigated. As a result of measuring the slump of the self - healing concrete, the target slump was satisfied in all the mixing conditions, but the slump was decreased as the mixing amount of the hydrogel support increased. The change of porosity due to incorporation of hydrogel support was minimal. As a result of the evaluation of the compressive strength of the self - healing concrete, the incorporation of the hydrogel support did not affect the strength. However, under the same mixing condition, the dispersion value of the specimens tended to increase with increasing hydrogel support contents. As a result of the permeability test of self-healing concrete according to the incorporation of hydrogel support, it was confirmed that the mixing ratio of hydrogel support was effective to decrease the permeability coefficient.