• Geomechanics and Engineering
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• v.3 no.2
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• pp.131-151
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• 2011

The electrical conductivity of a soil-water system is related to its engineering properties. By measuring the soil electrical conductivity, one may obtain quantitative, semi-quantitative, or qualitative information to estimate the in-situ soil behavior for site characterization. This paper presents the results of electrical conductivity measured on compacted kaolin clay samples using a circular two-electrode cell in conjunction with a specially designed compaction apparatus, which has the advantage of reducing errors due to sample handling and increasing measurement accuracy. The experimental results are analyzed to observe the effects of various parameters on soil electrical conductivity, i.e. porosity, unit weight, water content and pore water salinity. The performance of existing analytical models for predicting the electrical conductivity of saturated and unsaturated soils is evaluated by calculating empirical constants in these models. It is found that the Rhoades model gives the best fit for the kaolin clay investigated. Two general relationships between the formation factor and soil porosity are established based on the experimental data reported in the literature and measured from this study for saturated soils, which may provide insight for understanding electrical conduction characteristics of soils over a wide range of porosity.

• Computers and Concrete
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• v.10 no.3
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• pp.231-240
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• 2012

In this paper, the effect of finishing methods on the relationships between compressive strength, permeability and void ratio of porous concrete (POC) or pervious concrete is discussed, using core specimens taken from actually constructed POC pavement. To attain reliable performance in the construction work, a newly designed finisher for POC is developed, and the performances as well as methods for controlling void ratio are examined. The POC pavements were finished with three finishing methods viz., no finishing, finishing with standard compactor and finishing with prototype compactor. The results show that the prototype POC finisher is efficient in controlling the void ratio and the quality of POC pavements. The relationships between compressive strength as well as permeability and void ratio of the in-situ POC pavements finished by the prototype machine were obtained. They are slightly different from the laboratory test results owing mainly to the mold effect and the differences in compaction modes.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.166-171
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• 1999

Porous concrete contains about 20% voids after compaction so that it has high permeability which secures underground water resources. It is introduced in domestic since 1980' but has problems such as lack of optimized mixture, low strength and durability, efflorescence and other defects, etc. In this study, several mixture were designed based upon site works, and test specimens for compressive strength, tensile strength, flexual strength and permeability, were prepared in a laboratory. After 28days of curing, every performance was tested to find optimum mixture. The mixture was proposed as 380kg/㎥ of unit cement weight, 32% of W/C 10∼13mm of aggregate.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.410-413
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• 1998

Since early of 1980's, high. performance fiber has been developed by processing of ultrahigh molecular weight polyethylene(UHMWPE). UHMWPE fibers have high strength high modulus and excellent impact properties due to the strong C-C bond. Furthermore, the specific gravity of UHMWPE fibers is less than 1.0g/$\textrm{cm}^2$, which makes it possible to produce composites that combine good mechanical properties with low specific mass. (omitted)

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.112-119
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• 2000

the shaking table tests for 5 different model sections are performed to investigate the behaviors of quay walls during earthquakes and to evaluate the seismic performance of quay walls with countermeasures. 5 different model sections describe the cases of dense soil and loose soil in the foundation repectively the case to which gravel backfill was applied and the cases to which light material replacement method and sand compction pile method was applied repectively for sesmic countermeasure methods. Pore water pressures accelerations and deformations in quay walls and grounds are analyzed. As a result the softening of foundation and backfill soils have much influence on the behaviors of quay walls. Also light material replacement method and sand compaction pile method are effective in improving the seismic performance of quay walls.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.86-87
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• 2015

An active study on UHPC, which has been recently used in high-rise building and bridges, is in progress. However, research on bonding shear strength of UHPC is required to be studied due to the lack of information. In this study, experimental research progress for bonding shear strength (shear strength of adhesive surface) evaluation of UHPC (Ultra High Performance Concrete) is proceeded. First, specimens that surface treatment methods of concrete bonded section and retardation time of placement are considered are produced. Second, Direct Shear test is applied on concrete bonded section of UHPC. As a result of this study, the highest bonding shear strength specimen in which compared to the non-retardation time specimen is compaction turbulence treatment. From later study, it is judged that strength of UHPC in accordance with direction of steel fiber when steel fiber of UHPC is mixed.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.67-74
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• 2017

PURPOSES : The objective of this study is to ascertain the curing period of cementless cold central plant recycled asphalt base-layer, using mechanical analyses and specimen quality tests on the field. METHODS : Cold central plant recycled asphalt base-layer mixture was produced in the plant from reclaimed asphalt, natural aggregate, filler for the cold mix, and the modified emulsion AP using asphalt mix design and plant mix design. In order to examine the applicability of the curing period during the field test, the international standards for the possibility of core extraction and the degree of compaction and LFWD deflection were analyzed. Moreover, Marshall stability test, porosity test, and indirect tensile strength test were performed on the specimens of asphalt mix and plant mix design. RESULTS : The plant production process and compaction method of cementless cold central plant recycled asphalt base-layer were established, and the applicability of the optical moisture content for producing the mixture was verified through the field test. In addition, it was determined that the core extraction method of the conventional international curing standard was insufficient to ensure performance, and the LFWD test demonstrated that the deflection converges after a two-day curing. However, the back-calculation analysis reveals that a three-day curing is satisfactory, resulting in a general level of performance of dense asphalt base-layer. Moreover, from the result of the specimen quality test of the asphalt mix design and plant mix design according to the curing period, it was determined that the qualities satisfied both domestic and international standards, after a two-day curing. However, it was determined that the strength and stiffness after three-day curing are higher than those after a two-day curing by approximately 3.5 % and 20 %, respectively. CONCLUSIONS:A three-day curing period is proposed for the cementless cold central plant recycled asphalt base-layer; this curing period can be demonstrated to retain the modulus of asphalt-base layer in the field and ensure stable quality characteristics.

• Journal of the Korean Geosynthetics Society
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• v.19 no.4
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• pp.11-20
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• 2020

This study introduced the compact grouting method that can be used for improving soft ground and restoring buildings with unequal subsidence. The pump used in the traditional compact grouting method is a system that injects one hole each, which reduces the construction efficiency, and the analog injection method manually manages the construction by field workers, making it difficult to manage consistent quality. Pump and quality control system were developed to solve problems in existing construction. Since field supervisor determines amount of injected materials by using analog equipment and controls manually, it is difficult to manage consistent quality of construction. Therefore, the quality control system was developed in order to solve that problem. The quality control system consists of automatic mixing system of injection materials, multiple simultaneous injection pumps, and injection management monitoring system. Performance of the quality control system was verified through on-site testing, and ground improvement performance was verified through quality testing after testing and testing of the compact grouting method. Therefore, it is expected that the integrated quality control system developed will improve the quality assurance and efficiency and stability of construction at sites where construction and quality verification are difficult.

• Geomechanics and Engineering
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• v.28 no.6
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• pp.547-557
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• 2022

Dune sands are poorly graded collapsible soils lacking fines. This experimental study explored the technical feasibility of sustainable invigoration of fine waste materials to improve the geotechnical properties of dune sand. The fine waste considered in this study is fine marble waste. The fine waste powder was mixed with dune sand at different contents (5, 10,15, 20, 25, 50%), where the gradation, void ratio, compaction, and shear strength characteristics were assessed for each fine marble waste -dune sand blend. The geotechnical properties of the dune sand-fine marble waste mix delineated in this study reveal the enhancement in compaction and gradation characteristics of dune sand. According to the results, the binary mixture of dune sand with 20% of fine marble waste gives the highest maximum dry density and results in shear strength improvement. In addition, a numerical study is conducted for the practical application of the binary mix in the field and tested for an isolated shallow foundation. The elemental analysis of the fine marble waste confirms that the material is non-contaminated and can be employed for engineering applications. Furthermore, the numerical study elucidated that the shallow surface replacement of the site with the dune sand mixed with 20% fine marble waste gives optimal performance in terms of stress generation and settlement behavior of an isolated footing. For a sustainable mechanical performance of the fine marble waste mixed sand, an optimum dose of 20% fine marble waste is recommended, and some correlations are proposed. Thus, for improving dune sand's geotechnical characteristics, the addition of fine marble waste to the dune sand is an environment-friendly solution.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.3
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• pp.111-116
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• 2023

The WiscKey database, which optimizes overhead by compaction of the LSM tree-based Key-Value database, stores the value in a separate file, and stores only the key and value addresses in the database. Each time an fsync system call function is used to ensure data integrity in the process of storing values. In previously conducted studies, workload performance was reduced by up to 5.8 times as a result of performing the workload without calling the fsync system call function. However, it is difficult to ensure the data integrity of the database without using the fsync system call function. In this paper, to reduce the overhead of the fsync system call function while performing workloads on the WiscKey database, we use NVDIMM caching techniques to ensure data integrity while improving the performance of the WiscKey database.