• International Journal of Concrete Structures and Materials
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• v.4 no.2
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• pp.105-108
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• 2010

In order to determine the effect of the use of limestone sand on chloride ion ingress in mortar, specimens were cast with two different sands: siliceous sand (used as reference) and limestone crushed sand (used for this study). To compare and assess the resistance of this mortar to chloride penetration, two different diffusions tests were employed: slow migration and rapid migration (AASHTO test). In this study, calculation of the effective diffusion coefficient is proposed using a model based on Nernst. Planck equation. The diffusion coefficients from each sample were compared. The results for all tests show that the diffusion coefficients for siliceous sand mortar are larger than those obtained with limestone sand. It appears also that the diffusion coefficient varies as a function of the W/C ratio.

• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.45-51
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• 2008

Recently, the demand of ultra high-rise building is on the increase in korea due to the rapidly changing movement in economic growth and the expansion of national infrastructure. At the same time, the tendency toward the amount used of concrete has greatly increased every year. In addition, as the seriousness of quantity demanded of aggregate is gathering strength, the active areas of research proceeds to do actively in every place in order to review the usability of crushed sand as a part of the countermeasures. And, it needs to establish the quality standard and service guide, etc. for the practical use. Accordingly, this study was to establish the ratio of water-binder materials as three levels like 23.5, 27.5, and 31.5%, and the replacement ratio as three levels like 0, 50, and 100% in order to define the engineering properties of ultra high-strength concrete using the crushed sand. This study was to examine it after establishing the combined condition by the substitute of the fine aggregate percentage and admixture. From the result of this research above, it may be summed up as follows. 1) The more the replacement ratio of crushed sand and the ratio of water-binder materials increased, the mon the fluidity decreased due to the decrease of irregular grain shape of sand and unit combined discretion. 2) This study found out that 100% of replacement ratio of crushed sand was almost similar level to the compressive strength of concrete using the natural sand.

• Steel and Composite Structures
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• v.47 no.6
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• pp.781-794
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• 2023

In order to directly apply seawater and sea sand in construction without desalination, a type of square concrete-filled steel tube (CFST) encased with prefabricated seawater sea-sand concrete filled Polyvinyl Chloride (PVC)/Glass Fiber Reinforced Polymer (GFRP) tube column was proposed. Twenty short columns were tested under uniaxial loads, and the test parameters included inner tube types, seawater sea-sand concrete replacement ratios, concrete strength, the wrapping area of Carbon Fiber Reinforced Polymer (CFRP) strips and the thickness of GFRP tube. The effects of the parameters on failure modes, loading capacity, ductility and strain responses were discussed. All the tested specimens failed with serious buckling of the steel tubes and fracture of the inner tubes. The specimens had good residual bearing capacity corresponding to 64% to 88.9% of the peak capacity. The inner GFRP tubes and PVC tubes wrapped by CFRP strips provided stronger confinement to the core concrete, and were good choices for the proposed columns. Moreover, an analytical model for the composite column with different inner tube types was proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.437-440
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.54-59
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• 1998

This experimental Study presents the flow properties of mortar Using the Blast-furnace Slag Sand. It gives following result. The substitution rate is inversely proportional to flow. But W/C ratio is directly proportional to flow. Consequently Flow characteristics of the Blast-furnace mortar is simillar to the river sand mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.121-124
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• 2005

As a countermeasure about that, in this situation that suggest utilizing mixed drush sand and particle washed sand, this study is reviewing and comparing, as a experimental and positive test, mixed both workability and engineering properties of mortar, The purpose of this study make a suggestion that is fundamental data for utilizing mixed crush sand and particle washed sand.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.419-422
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• 2005

This paper is examined the properties of Haeju sea sand for concrete. As result, the water absorbtion ratio and the contents of shell and microfines of Haeju sea sand was high. We would expected to utilize the results of this study as a basic data for quality control of Ready Mixed Concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.141-144
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• 2006

In this study, evaluation of physical and chemical properties of crushed sand was performed to establish optimal mix proportion standard for concrete using crushed sand afterward. Most of properties of crushed sand were satisfied with KS F 2527. Especially, chemical stabilities such as alkali-aggregate reaction were fairly good. However, considerable attention would be required in using crushed sand from lime stone judging from the result that weight loss of it was more than 23.8%. There were some differences in the properties with production region, stone type and capacity of facility, therefore it is thought that quality should be controled by optimal regulations for corresponding items.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.57-61
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• 2006

Waste foundry sand of industrial waste which is happening by vast quantity according to fast development of industry has much the occurrence amount and processing method is depended on reclamation, and is using by fine aggregate for construction by recycling method among others. In this research Waste foundry sand powder into cement replace fare use possibility availability judge wish to Slump and air content decreased the replacement ratio increases by concrete special quality that do not harden according to experiment result, and unit capacity mass and bleeding increased the replacement ratio increases. Hardening concrete intensity special quality displayed strength improvement to replacement ratio 20%, and tendency that watertightness increases most in replacement ratio loft in watertight property appear. Considering the strength and watertight properties, the adequate usage of waste foundry sand powder is the 10% of replacement ratio.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3719-3725
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• 2012

Due to the recent shortage of well-graded river sand resulting from a rapid growth of concrete construction, sea sand, crushed sand, and etc. are increasingly used instead. It is, however, well noted that non-washed sea sand leads to corrosion of the reinforcing steel in concrete, and thus eventually results in damage to concrete. Also, the crushed sand is not being widely used, since it is difficult to maintain the allowable amount of passing 0.08mm sieve and to adjust grading. On the other hand, because the fine sand of Nakdong-River has a poor grading but good quality as a fine aggregate for concrete, it is strongly needed to investigate the fine sand as an alternative fine aggregate. Thus, the purpose of this research is to evaluate the physical properties of the fine sand of Nakdong-River to utilize it actively as a fine aggregate. For this purpose, after the sand samples were collected according to typical location of main stream of Nakdong-River, the physical properties such as density in oven-dry condition, grading, unit volume mass, and etc. of them were estimated. It was observed from the test results that physical properties of the fine sand of Nakdong-River except grading were found to be excellent.