• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.5
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• pp.69-77
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• 2012

Relative density, used to express dynamics condition of sand quantitatively, is measured by RI Test, Standard Penetration Test and Cone Penetration Test. Each measurement method has demerits, which is complicated or needs a specific analysis instrument and an analysis of expert. Also the ground is in wet condition commonly because of an unsaturated zone between a saturated zone and a surface, so the behaviour of the ground has different engineering properties unlike the dry ground and it diminishes accuracy of measuring relative density. In this study, the correlation between relative density and penetration of fall cone test in dry condition and wet condition with variation of water content was analyzed and a simple measuring method for relative density was suggested. As a result, there were difference of penetration between dry sands and wet sands, the correlation between relative density and penetration showed linear expression and relative density could be measured by the linear relation.

• Geomechanics and Engineering
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• v.8 no.1
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• pp.1-15
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• 2015

This paper presents a series of conventional undrained triaxial compression tests conducted to determine the effect of both tire crumbs and cement addition on Narli sand specimens. The tire crumb contents and cement contents were 3%, 7%, 15%; and 1%, 3%, 5% by dry weight of the sand specimens respectively. Specimens were prepared at about 35% relative density, cured during overnight (about 17 hours) for artificially bonding under a 100 kPa effective stress (confining pressure of 500 kPa with a back pressure of 400 kPa), and then sheared. Deviatoric stress-axial strain, pore water pressure-axial strain behavior, and Young's modulus of the specimens at various mixture ratios of tire crumb/cement/sand were measured. Test results indicated that the addition of tire crumb to sand decreases Young's modulus, deviatoric stress and brittleness, and increase pore water pressure generation. The addition of cement to sand with tire crumbs increases deviatoric stress, Young's modulus, and changes its ductile behavior to a more brittle one. The results suggest that specimen formation in the way used here could reduce the tire disposal problem in not only economically, and environmentally, but also more effectively beneficial way for some geotechnical applications.

• KCID journal
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• v.5 no.2
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• pp.9-19
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• 1998

A series of model tank and rigid wall permeameter tests was performed in order to determine the long-term hydraulic conductivity of the sand-bentonite liners reinforced by geotextile. Main conclusions are as follows 1. The maximum dry density and optimum

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.138-143
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• 1993

The objective of this report is to investigate the effect of factors like the fineness modulus of sand , content of fly ash and slaked lime, binder/sand ratio, admixture dosage on the physical properties of mortar for finishing. The analysis was performed with design of experiment and air content, water retention and compressive strength were measured.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.75-84
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• 2008

This study was carried out to examine the effects of cornstarch-based absorbent polymer (CAP) on the growth of cool season turfgrasses in sand-based soil mixture. Kentucky bluegrass + perennial ryegrass mixtures seeded at May 18 in 2006 on sand-based soil mixture. Sand + peat (5%, v/v), sand + CAP $20g{\cdot}m^{-2}$, sand + CAP $20g{\cdot}m^{-2}$ + peat (5%, v/v), and sand + CAP $40g{\cdot}m^{-2}$ + peat (5%, v/v) mixtures were compared. Ground coverage of sand + CAP $20g{\cdot}m^{-2}$ + peat (5%, v/v), and sand + CAP $40g{\cdot}m^{-2}$ + peat (5%, v/v) treatments showed 50% at a month after seeding. But the coverage of sand + peat (5%, v/v), sand + CAP $20g{\cdot}m^{-2}$ resulted in 36.7%. Mixing of CAP with sand was considered to be efficient method for increasing ground coverage as much as peat. Dry weight of turfgrass tiller at sand + CAP $20g{\cdot}m^{-2}$ + peat (5%, v/v), and sand + CAP $40g{\cdot}m^{-2}$ + peat (5%, v/v) were also significantly higher than sand + peat (5%, v/v), sand + CAP $20g{\cdot}m^{-2}$ mixtures at a month after seeding. Soil water retention at the sand + CAP $20g{\cdot}m^{-2}$, sand + CAP $40g{\cdot}m^{-2}$ + peat (5%, v/v) mixing were lower than sand + peat (5%, v/v) and sand + CAP $20g{\cdot}m^{-2}$ + peat (5%, v/v) during the dry periods. From the results, the mixing of CAP with sand is useful to increased ground coverage of kentucky bluegrass and perennial ryegrass.

• Geotechnical Engineering
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• v.11 no.1
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• pp.101-112
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• 1995

Deformational characteristics of soils, often expressed in terms of shear modulus and material damping ratios, are important parameters in the design of soil-structure systems subjected to cyclic and dynamic loadings. In this paper, deformational characteristics of dry sand at small to intermediate strains were investigated using resonant column/torsional shear(RC 175) apparatus. Both resonant column(dynamic) and torsional shear (cyclic) tests were performed in a sequential series on the same specimen. With the modification of motion monitoring system, the elastic zone, where the stress strain relationship is independent of loading cycles and strain amplitude, was veri tied and hysteretic damping was found even in this zone. At strains above cyclic threshold, shear modulus increases and damping ratio decreases with increasing number of loading cycles. Moduli and damping ratios of dry sand are independent of loading frequency and values obtained from pseudostatic torsional shear tests are Identical with the values from the dynamic resonant column test, provided the effect of number of loading cycles is considered in the conlparison. Therefore, deformational characteristics determined by RC/TS tests may be applied in both dynamic and static analyses of soil-structure systems.

• Journal of the Korean Geotechnical Society
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• v.33 no.7
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• pp.17-28
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• 2017

This paper presents the investigation of dynamic behavior of a single pile in dry sand based on 1g shaking table tests. The natural frequency of soil-pile system was measured, and then a range of loading frequency was determined based on the natural frequency. Additionally, the studies were performed by controlling loading accelerations, pile head mass and connectivity conditions between pile and cap. Based on the results obtained, relatively larger pile head displacement and bending moment occur when the loading frequency is larger than the natural frequency of soil-pile system. However, the slope of the p-y curve is smaller in the similar loading frequency. Also, it was found that inertia force like input acceleration and pile head mass, and relation of the natural frequency of soil-pile system and input frequency have a great influence on the slope of dynamic p-y curve, while pile head conditions don't.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.11-19
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• 2021

The aim of the research is providing a fundamental data on quality and constructability of direct tile setting method depending on various cement to sand ratio for tiling dry cement mortar. A large number of tile setting failures reported is related with the cement mortar and its construction for tiling. Because of different materials of tiles, the properties of tiling dry cement mortar, an adhesive for tiling, can influence on quality and constructability of tiling differently. Practically, the easiest way of controlling the properties of the tiling dry cement mortar is to control the proportion of cement and sand. Hence, in this research, sand to cement ratio (S/C) was controlled. Since there is no standarized method on evaluating performance of dry cement mortar for tiling, a several sensory evaluation methods were suggested and executed. According to the experiments conducted in this research, the adhesive performance of cement mortar for tiles can be different depending on the sides such as tile and substrate. Additionally, depending on S/C, finishability, initial adhesive performance, and tile shifting resistance can be changed for ceramic tile. Therefore, under the conditions of this research, about 5 of S/C can be recommended for appropriate performace of tiling dry cement mortar.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.792-797
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• 2009

The stress-strain characteristics of compacted bentonite are investigated using experimental triaxial compression test by Hoek-cell. Special attention given to various dry density and water absorption ratio. Based on the test results, it is shown that the stress-strain relationship of compacted bentonite is highly influenced by dry density and water absorption ratio. Also, characteristics of Bentonite is similar to the clay rather than sand. Strength of compressed Bentonite increases with higher dry density. It shows maximum strength value, if in a same condition with dry density and constrain pressure. So we determine that value as the optimistic moisture contents for the maximun strength of compressed Bentonite.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.405-410
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• 1996

To elucidate the pattern of nutrient absorption and endosperm consumption as the seedling age of rice, Dongjinbyeo was raised in the seedling box with different nitrogen levels. Absorption of nitrogen and phosphorus were high in the order of artificial seed bed soil, sand with N-1g /box and sand without N from 3 and 5 days after seeding but, potassium wasn't significantly different between sand＋N-1g /box and sand. Endosperm consumption rate was high in the order of artificial seed bed soil, sand ＋ N-1g /box and sand but, endosperm dependence rate (endosperm consumption /top dry weight) was vice versa. Seedling height and dry weight were higher in the order of artificial seed bed soil, sand+N-1g /box and sand from 3 days after seeding, number of leaves were more from 5 days after seeding in same order.