• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.04a
• /
• pp.40-45
• /
• 1993

Due to the recent shortage of river sand resulting from a rapid growth of concrete construction, sea sand and pit sand are increasingly used in stead. It is , however, well noted that non-washed sea sand used in reinforced concrete causes to corrode reinforcing steel and to incur cracks in concrete, and thus eventually result in damage to concrete. Moreover, many sources of pit sand in our country are randomly used without experimental research for its applicability to concrete construction. The purpose of this research to activate the usage of pit sand and sea sand for concrete construction to solve the recent shortage of river sand. Followings have been experimentally investigated : 1)Physical properties of pit sand and sea sand, 2)Compressive strength of mortar on the weight of pit sand passing through No.200 sieve, 3) Compressive strength of mortar on the chloride content of sea sand, 4) Compressive strengths of concrete using pit sand and sea sand, respectively, 5)Corrosion propagatio in reinforcing steel on the chloride concent, of sea sand, and 6)etc.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.451-454
• /
• 2005

Recently, Trouble of sand supply is occurred according to exhaustion of natural sand resources. therefore, various measures are proposed for solution of trouble of sand supply and crushed sand among measures is used as one of most universal measures. but because crushed sand have poor particle shape and plenty of makes micro particle, the quality of concrete using crushed sand deteriorated. Therefore, this study evaluated engineering property of concrete with replacement ratio of crushed sand and applied evaluation result to fundamental data for quality control of concrete using crushed sand. The result of this study have shown that quality of concrete using crushed sand independently is poor against general concrete. but, the concrete mixing crushed sand with general sand can be similar in workability of concrete used general sand and increase compressive strength of concrete as against concrete using general sand.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.455-458
• /
• 2005

This study compares the concrete using natural sand with the concrete using crush sand for the examination for the properties of a concrete. In the fresh concrete, the concrete using crush sand has less of the quantity of consistency, the content of air, and bleeding than the concrete using natural sand, and the concrete using crush sand has faster setting time than the concrete using natural sand. In hardening concrete, the concrete using crush sand has higher compressive strength and tensile strength than the concrete using natural sand because minute particles fill up a gap. Drying shrinkage of the concrete using natural sand is less than the concrete using crush sand.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.105-108
• /
• 2006

Recently, trouble of sand supplying is occurred according to exhaustion of natural sand resources. Therefore various measures are proposed for solution of trouble of sand supply and crushed sand among measures is used as one of most universal measures. But because crushed sand have poor particle shape and plenty of mikes micro particle, the quality of concrete using crushed sand deteriorated. Therefore, this study evaluated engineering property of concrete with replacement ratio of crushed sand and EEZ sand applied evaluation result to fundamental data for quality control of concrete using crushed sand and EEZ sand and The result of this study have shown that quality of concrete using crushed sand and EEZ sand and The compressive strengh of concrete up to 50, 70% EEZ sand replacement by crush sand, nearly equal to that of general sand.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.53-56
• /
• 2006

Recently, trouble of sand supplying is occurred according to exhaustion of natural sand resources. Therefore various measures are proposed for solution of trouble of sand supply and crushed sand among measures is used as one of most universal measures. But because crushed sand have poor particle shape and plenty of makes micro particle, the quality of concrete using crushed sand deteriorated. Therefore, this study evaluated engineering property of concrete with replacement ratio of crushed sand and EEZ sand and applied evaluation result to fundamental data for quality control of concrete using crushed sand and EEZ sand. The result of this study have shown that quality of concrete using crushed sand and EEZ sand and The compressive strength of concrete up to 50, 70% EEZ sand replacement by crush sand, nearly equal to that of general sand.

• Journal of the Korea Institute of Building Construction
• /
• v.3 no.3
• /
• pp.107-112
• /
• 2003

This study is to investigate the properties of concrete with crushed sand on site and to propose a quality guideline for its use as artificial sand and concrete. From our experimental result in laboratory and site, we found that demand water of concrete with crushed sand for target slump increased by 18kg/m3 compared to mixed sand and l8kg/m3 compared to sea sand respectively. The compressive strength increased by around 3∼6% when compared to concrete with sea sand. Accordingly, our study showed that the combined sand mixed with sea sand would be desirable to obtain workability and strength of concrete including dry shrinkage and bleeding test. Furthermore, the optimal replacement percentage of crushed sand was 50% with sea sand. As such, crushed sand would be sufficient as fine aggregate for concrete in terms of economic efficiency and quality. Crushed sand, on the other hand can only be used as fine aggregate when VFS(Very Fine Sand) is below 3.5 percentage of weight of sand and particle shape is above 55 percentage. Also, the particle shape and microsand passing NO.200 sieve should continually be improved to increase workability of concrete on site.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.106-111
• /
• 2003

This paper is to investigate the characteristics of a concrete in which river sand is partially substituted with crushed sand. Since river sand has a relatively small fineness modulus, there is a need to increase the fineness modulus of sand used in the manufacture of concrete. In an experiment, it was observed that when river sand had a fineness modulus of 2.0~2.4 and crushed sand had a fineness modulus of 2.8~3.5, the substitution rate of the crushed sand was preferably within the range of 25~50%. The experimental results also revealed that as the substitution rate of the crushed sand increased, the flowability of the concrete tended to increase. However, when the substitution rate of the crushed sand reached 75% or more, the workability of the concrete was considerably poor. Further, as the substitution rate of the crushed sand increased, the air content and the bleeding rate of the concrete were low.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.147-152
• /
• 1998

This study is to investigate the application of concrete with crushed sand on site. As a result, it is showed that the combined sand mixed with sea sand is very desirable for obtaining workability and strength of concrete, and the optimal replacement percentage of crushed sand is 50% with sea sand. After all, the crushed sand could be sufficiently used as a fine aggregate for concrete in the aspect of economical efficiency and quality, but the particle shape and microsand passing No.200 sieve should be firstly improved for increasing workability of concrete on site.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04a
• /
• pp.117-122
• /
• 1998

Concrete structures has been deteriorated by the freezing and thawing due to temperature gap. This study was conducted to evaluate durabilite of concrete which are increasingly demanded recently. Therefore the research of durability must be executed for application of waste foundry sand concrete real structures. Concrete durability must be executed for application of waste foundry sand concrete real structures. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at $-18^{\cire}C$ and $4^{\cire}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that strength of concrete is increased the W/C ratio decrease, the Sand/Waste foundry sand ratio increase when the concrete contains AE agent and decreasing WC ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row. Therefore it is turn out the waste foundry sand could be applied to concrete from the experiment.

• International Journal of Concrete Structures and Materials
• /
• v.4 no.2
• /
• pp.97-104
• /
• 2010

The crushed limestone sand is an abundant material in Tunisia, which induces many environmental problems. Indeed, available stocks of siliceous sand drastically decrease because of its massive use in hydraulic concrete. Some recent research works, carried out in Tunisia, concluded that crushed limestone sand may be used in concrete manufacture instead of siliceous sand traditionally used. In this context, an experimental study was achieved in order to quantify the influence of a partial or total substitution of siliceous sand by crushed limestone sand on hydraulic concrete performances. Preliminary chemical and physical tests on crushed sand indicated that it presented the minimum requirement for its use as aggregate in hydraulic concrete. 79 concretes were then prepared with siliceous sand, crushed limestone sand and a mix of the two sands. Their slump value and compressive strengths were measured on plain concretes. Complementary structural tests on reinforced concrete beam were also performed. The results proved that crushed limestone sand concretes showed workability and mechanical performances closed to those of siliceous sand concretes.