• Geophysics and Geophysical Exploration
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• v.18 no.4
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• pp.171-180
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• 2015

Electrical resistivity of 23 core samples from Ulleung Island at dry or saturated condition has been measured along with dry density and effective porosity, and the relations between the properties has also been discussed. Upper and lower bounds of electrical resistivity at room temperature can be provided by the dry- and saturated-resistivity, respectively. Injecting nitrogen gas to the pore space at the very end of drying process can prevent humid air from getting into the pore space, so that measurement of dry-resistivity can be less affected by humidity in the air. Dry density and porosity have very close correlation; the ratio between increase of porosity and the decrease of density showed distinct relation to the rock types, such that basaltic rocks showed higher ratio while trachytic rocks showed lower. Saturated resistivity showed close correlation to density and effective porosity of the rock sample, while dry resistivity didn't.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.428-434
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• 2022

This study intends to develop an eco-friendly concrete panel mixed with biochars. Experiments about mechanical and thermal properties were conducted on porous biochar concrete, which has insulation and carbon-capture performance. The concrete has a mixing ratio of 0, 5, 10, and 15 % for biochar and a water-binder ratio of 0.35. The unit weight, porosity, and permeability were measured to evaluate the mechanical characteristics. From the results, as the biochar mixing rate increased, the porosity and the permeability increased, but the unit weight decreased. Even though a decreased trend was observed in the compressive strength results, they satisfied the design standard. Since the thermal conductivity was decreased during the increase of contents, biochar could be considered an excellent material for insulation performance. In addition, regression analyses were conducted regarding the relationship of unit weight with porosity, compressive strength with thermal conductivity, and porous with thermal conductivity. From the regression, significant variables for expanding the scope of the application of biochar were presented.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.2
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• pp.145-152
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• 2023

In this study, microscopic observation was made on the surface of cement paste immersed in an aquatic environment for 100 days at electrochemical treatment to mitigate the leaching of alkali ions. To quantitatively rank the hydration products, unhydrated grains and porosity in the interfacial region, the backscattered electron(BSE) images were obtained by scanninng electron microscopy. As a result, it was found that the porosity on the surface was significantly reduced by the electrochemical treatment, while unhydrated grains were more or less increased presumably limited hydration reaction under electric charge. At electrochemical treatment, Ca²⁺ ions present in C-S-H gel could be precipitated with OH^- to form Ca(OH)₂ then to lower C-S-H gel and simultaneously to enhance Ca(OH)₂. Substantially, the risk of alkali leaching could be lowered by the limited ionized matrix under electrochemical treatment.

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.367-375
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• 2010

Understanding the interactions between earth materials and fluids is essential for studying the diverse geological processes in the Earth's surface and interior. In order to better understand the interactions between earth materials and fluids, we explore the effect of specific surface area and porosity on structural parameters of pore structures. We obtained 3D pore structures, using random packing simulations of porous media composed of single sized spheres with varying the particle size and porosity, and then we analyzed configurational entropy for 2D cross sections of porous media and cube counting fractal dimension for 3D porous networks. The results of the configurational entropy analysis show that the entropy length decreases from 0.8 to 0.2 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$, and the maximum configurational entropy increases from 0.94 to 0.99 with increasing porosity from 0.33 to 0.46. On the basis of the strong correlation between the liquid volume fraction (i.e., porosity) and configurational entropy, we suggest that elastic properties and viscosity of mantle melts can be expressed using configurational entropy. The results of the cube counting fractal dimension analysis show that cube counting fractal dimension increases with increasing porosity at constant specific surface area, and increases from 2.65 to 2.98 with increasing specific surface area from 2.4 to $8.3mm^2/mm^3$. On the basis of the strong correlation among cube counting fractal dimension, specific surface area, and porosity, we suggest that seismic wave attenuation and structural disorder in fluid-rock-melt composites can be described using cube counting fractal dimension.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.493-496
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• 2007

본 연구에서는 국내 암석을 암종별로 총 292개 채취하였으며 열물성 측정 장비를 이용하여 이들 암석의 열물성을 측정하였다. 이와 더불어 암석의 물리적 특성을 측정하였으며 일부 시료의 경우 XRD 정량분석을 실시하였다. 이들 결과를 이용하여 암석의 열물성 특성과 열물성에 영향을 주는 인자를 파악하였다. 암석의 열물성 측정 결과 열전도도와 열확산계수는 화강암에서 가장 낮은 값을 보였으며 퇴적암, 변성암 순으로 나타났다. 또한 암종별 열물성 값의 범위를 살펴보면 변성암과 퇴적암에서 넓게 분포한다. 암석의 물성과 열물성과의 상관성 분석 결과 공극률이 증가함에 따라 열전도도와 열확산계수가 감소하나 상관성은 미약한 것으로 나타났다. XRD 분석 결과 암석의 열전도도는 석영($SiO_2$)의 함량에 따른 선형의 비례관계를 보였다. 이로써 암석의 열전도도는 암석을 이루는 광물의 종류에 의하여 영향을 받음을 알 수 있다. 차후 암석의 구성 광물입자의 배열 상태에 따른 열물성 특성과 퇴적암 및 변성암 시료에 대한 이방성 실험을 통해 편리, 층리 및 엽리 등에 따른 열물생의 이방성 정도를 분석할 예정이다.

• The Journal of Engineering Geology
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• v.16 no.3 s.49
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• pp.301-306
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• 2006

Damages of cultural properties is caused by subsidence of foundation relating stone structures. To prevent of these structures, ground monitoring should be achieved certainly. Representative ground subsidence cause is saturated and unsaturated condition that is produced repeatedly by groundwater level fluctuations. It controls role that decrease porosity or effective porosity of soil media. Estimation of physical properties can predict from reaction of dielectric constant. Variations of dielectric constants are measured from physical characteristics change of pore, soil particle, air and water which are consisted to ground. Therefore, ground subsidence monitoring is thought that quantitative measurement is available using dielectric response of media.

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.40-49
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• 2008

Matrix diffusion from planar fractures was studied mathematically and through physical model experiments. Mathematical models were developed to simulate diffusion from 2D and 3D instantaneous disk sources and a 3D continuous disk source. The models were based on analytical solutions previously developed by Carslaw and Jaeger (1959). The mathematical simulations indicated that the 2D scenario produces significantly different results from the 3D scenario, the time for mass disappearance is significantly larger for continuous sources than for instantaneous sources, the normalized concentration generally decreased over time for instantaneous sources while it increased over time for continuous sources, diffusion rates decrease significantly over time and space, and the normalized mass loss from the source zone never reaches 1 for continuous sources due to the semi-infinite integral. The simulations also showed that disappearance times increase exponentially with increasing source radii and matrix porosity, and decrease with increasing aqueous-phase NAPL solubilities.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.276-283
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• 2012

Changes in rock properties due to freezing and thawing cycles ranging from $-20^{\circ}C$ to $10^{\circ}C$ were checked for the typical Korean rocks: granite (weathered), limestone, sandstone, tuff, shale and basalt. The porosity, seismic velocity, shore hardness and specific gravity were measured every 10 cycles for each type of rock up to 40 cycles. The specific gravity was rarely changed. Granite (w), shale and basalt decreased gradually in their shore hardness and seismic velocity values, these values for limestone, sandstone and tuff changed only a very little. The porosity increased in the granite (w), shale and basalt, whereas in the others it did not change. Due to the low tensile strength with high porosity, granite (w), shale and basalt were susceptible to the F-T cycles. A linear regression equation was calculated based on the experiment results according to properties and types of rock. The relationship between the freeze-thaw sensitivity (=initial porosity/initial tensile strength) and the coefficients of the regression equation was examined. With additional experimental data, the coefficients of the regression equation can be estimated using the F-T sensitivity. This makes it possible to predict the properties of rock as affected by freeze-thaw weathering by only measuring the initial properties without knowledge of the regression equation coefficients for each type of rock.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.953-956
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• 2008

The purpose of this study is to ascertain the void ratio, permeability coefficient and compressive strength of porous polymer concretes with unsaturated polyester. The porous polymer concretes using unsaturated polyester with polymer binder contents of 3.5, 4.0, 4.5 and 5.5% are prepared, and tested for void ratio, permeability coefficient and compressive strength. As a result, void ratio and permeability coefficient of porous polymer concrete decrease with increasing polymer binder content. However, the compressive strength of porous polymer concrete increase with increasing polymer binder content. The compressive strength of porous polymer concrete decrease with increasing permeability coefficient.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.199-206
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• 2018

Due to the advantages of less raw materials and fossil fuel consumption, lower carbon footprint, and the capability of pavement performance improvement, the recycling technology of asphalt is developed and applied for road rehabilitation and construction in the western countries over the past two decades. Cold recycled asphalt mixtures are bituminous materials normally made by mixing recycled aggregate from wasted asphalt with an asphalt emulsion and water at room temperature. This paper aims at investigating the properties of cold recycled asphalt mixture with alkali-activated filler according to wasted asphalt aggregate content. As a result, as the content of wasted asphalt aggregate increased, the marshall stability of cold recycled asphalt mixture decreased and void ratio increased. Also, grading curves for cold recycled asphalt mixture as specified in GR criteria were satisfied in all aggregate mixing conditions regardless of the wasted asphalt aggregate content.