• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.91-98
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• 2000

Porous concrete having continuous voids is gaining more interest as an ecological material. It has several useful functions such as water and air permeability, sound absorption, etc. Its strengths are considerably lower than those of conventional concrete due to the large and continuous voids in it. This study has been carried out to investigate the influence of mix factors and mixture proportion of aggregate on the strengths and water permeability of porous concrete. And it has been carried out to investigate the evaluation of void of porous concrete by the ultra-sonic pulse velocity. The results f this study are as follows: 1) The theoretical void ratio has greater influence than any other factor on the strengths and water permeability of porous concrete. And it is a little affected by the replacement proportion of silica-fume and mixture proportion of aggregate. 2) Because the coefficients of correlation between the void ratio and ultra-sonic pulse velocity were relatively high, it will be possible that the void ratio is predicted by the ultra-sonic pulse velocity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.104-112
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• 2019

The material properties of the 3D printing cement composite mortar were evaluated, and the performance range in which printing was possible was calculated using the void ratio in a fresh state as a single index. As a results of the tests, as the water-binder ratio (W/B) increased, the mortar flow value increased and the density and strength decreased. As the sand-binder ratio (SS/B) increased, the mortar flow value decreased. However, strength and density increased and decreased up to a certain SS/B. As admixture-binder ratio (Ad/B) increased, mortar flow value, density, and strength decreased. These trends make it difficult to mix-design to meet the target performances of 3D printing mortars, represented by extrudability and buildability. The value of mortar flow increased proportionally with the void ratio, while the density and strength apparently decreased as the void ratio increased. This indicates that void ratio can be utilized as a single index for controlling the material properties in the design of mortar mixtures. It was found that mortar mixture could be printed by a 3D printer when the void ratio was in the range from 0.6 to 0.7. This was verified by printing a mortar which has the void ratio of 0.634. The mortar was produced with the mixture design of W/B 35.0%, SS/B 60.0%, and Ad/B 0.1%. Further research applying diverse admixtures is needed to improve the quality of 3D printing output mortars.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.67-73
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• 2015

This study evaluated the effects of fibers on the void ratio, compressive strength and repeated freezing and thawing resistance of porous vegetation concrete with binder type (non-sintering inorganic binder and blast furnace slag cement) and natural jute fiber volume fraction (0.0 %, 0.1 % and 0.2 %). The natural jute fiber volume fraction affected the void ratio, compressive strength and repeated freezing and thawing resistance. Added of natural jute fiber resulted in improved properties of the void ratio, compressive strength and freezing and thawing resistance. Also, the both compressive strength and freezing and thawing resistance increased with natural jute fiber volume fraction up to 0.1 % and then decreased with fiber volume fraction at 0.2 %.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1290-1295
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• 2008

The relative density of soil indicate loose and dense state of sand. Because sand is low compressibility, initial relative density of sand is important effect factor of compression and shear behavior. To measure exactly relative density, the exactly maximum and minimum void ratio was determinated by laboratory tests. Generally, vibrating table method is adapted for minimum void ratio(KS F 2345). However KS F 2345 is not consider the particle break during the vibrating table test. In this study, The minimum void ratio is compared with a method of Pluviation and Vibrating table test results using the K-7(crushed sand). It is concluded that the K-7 sand particles were crushed during the vibrating table test and vibrating table test is not a suitable test for a crushed sand $e_{min}$.

• Geomechanics and Engineering
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• v.17 no.1
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• pp.19-30
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• 2019

Recent research on the behavior of silty sand tends to advocate the use of equivalent skeleton void ratio to characterize the density state of this type of soil. This paper presents an investigation to explore the physical meaning of the equivalent skeleton void ratio by means of DEM simulations for assemblies of coarse and fine particles under biaxial shear. The simulations reveal that the distribution pattern of fine particles in the soil skeleton plays a crucial role in the overall macroscopic response: The contractive response observed at the macro scale is mainly caused by the movement of fine particles out of the force chains whereas the dilative response is mainly associated with the migration of fine particles into the force chains. In an assembly of coarse and fine particles, neither all of the fine particles nor all of the coarse ones participate in the force chains to carry the external loads, and therefore a more reasonable definition for equivalent skeleton void ratio is put forward in which a new parameter d is introduced to take into account the fraction of coarse particles absent from the force chains.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.159-170
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• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.3
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• pp.85-91
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• 2002

This study is performed to evaluate characteristics of plantable concrete using waste stone and stone dust. The test result shows that the void ratio is decreased as the size of waste stone smaller and the content of stone dust increased. The strength of neutralized plantable concrete is decreased by approximately 4∼5% than that of the normal plantable concrete. The reduction effect of pH value is achieved by chemical treatment. Also, the plant is grown well with increase of the void ratio and size of waste stone.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.243-248
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• 2002

As a notion of environment protection changes throughout the world, construction engineers, as part of the effort to resolve environmental problems, have been actively doing research on environmental friendly porous concrete using large and non-uniform aggregate. Porous Concrete enables water and air to pass through a firmly hardened material and allows required nutrients to reach roots of plants. The purpose of this study is to analyze planting ability when the change of aggregate gradation and void ratio. The results of an experiment from the planting ability of the porous concrete to its influence on the compressive strength are reported in this paper. As a result of the experiment, the compressive strength is higher when the gradation of aggregate is smaller, and it also goes higher when the void ratio gets smaller The planting ability of porous concrete is decided by the germination and the grass length of Indigofera pseudo-tinctoria(IPT). The length of IPT is longer when the gradation of aggregate is greater and the void ratio gets smaller.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.513-516
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• 2004

The purpose of this study is to investigate properties of porous concrete according to volume of binder and compaction energy. The result of this study, as compaction energy goes on increasing, the actual measured void ratio is decreased according as a change of compaction energy and volume of binder. The compaction energy has a very near value by target void ratio on the whole when it is $50kN{\cdot}m/m^2,\;50\~75kN{\cdot}m/m^2$ in case of target void ratio is $15\%\;and\;25\%$. As compaction energy goes on increasing, compressive strength of specimens picked up when target void ratio is $20\%\;and\;25\%$. Also, compressive strength of specimens bluntly picked up when compaction energy is over $50\~75kN{\cdot}m/m^2$.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.199-202
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• 2003

A study for permeability and erosion characteristics of short fiber reinforced soils was performed. As mixing ratio increases from 0 to 1.0% permeability of short fiber reinforced soils increased but, maximum increment ratio($k_{1.0%}/k_{0%}$) was 8.47. As a result of permeability test with 19, 38 and 60mm fiber reinforced soils, there were no difference in fiber length. Void ratio increased with increment of mixing ratio and decrease of compaction energy and as a result of plotting permeability and void ratio, log k increased linearly by void ratio. As a result of erosion test, soil erosion was decreased sharply by increase of fiber mixing ratio up to 1.0%. Despite increase of soil erosion by slope angle, the increment ratio was decreased by mixing ratio.