• International Journal of Concrete Structures and Materials
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• v.6 no.4
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• pp.231-237
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• 2012

Recently, it has been difficult to get natural sand for concrete due to an insufficient supply in Korea. Crushed sand was thought as a substitute and previous research has been focused on low fluidity and normal compressive strength (24-30 MPa). Study on high performance concrete using crushed sand is hardly found in Korea. In this study it was investigated that the effect of the crushed sand on fluidity and compressive strength properties of high performance concrete. Blending crushed sand (FM: 3.98) produced in Namyangju, Kyunggido and sea sand (FM: 2.80) produced in Asan bay in Chungnam. The final FMs of fine aggregate were 3.50, 3.23, and 3.08. W/B was set as 0.25 to get high performance. With the test results an analysis of relationship was performed using a statistical program. It was shown that strength property of concrete using crushed aggregate at the very early age or after specific time was mainly affected by strength development properties of binders instead of the crushed sand.

• Advances in materials Research
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• v.11 no.4
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• pp.251-277
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• 2022

Disposal of industrial waste in cities where municipal authorities permitting higher floor area ratio coupled with increasing living standards, a lot of demolition waste is being generated. Its disposal is a challenge particularly in megacities where no landfills are available. The ever-increasing cost of building construction materials also necessitates consuming demolition wastes in a useful manner to save fresh natural raw materials. In the present work, the crushed waste glass is used in high-strength concrete as a partial replacement of fine aggregate. The control concrete of grade M60 was proportioned following BIS 10262-2009. The crushed waste glass has been used as a partial replacement with varying percentages of 10, 20, 30, and 40% by weight of fine aggregate. Experimental tests were carried on the fresh and hardened state of the concrete. The effect of crushed waste glass on the workability of the concrete has been investigated. Non-destructive tests, acid attack tests, compressive strength, split tensile strength, and X-ray diffraction analysis was carried out for the control concrete and concrete containing crushed waste glass after 7, 28, and 270 days of normal curing. The results show that for the same w/c ratio, the workability of concrete increases with increasing replaced crushed waste glass content. However, the decrease in compressive strength of the concrete after 28 days of normal curing and further after 28 days of acid attacks, up to 30% replacement level of fine aggregate by the crushed waste glass is insignificant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.85-88
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• 2006

This study investigated influence of fine aggregate types on fundamental properties of cement mortar. Test showed that concrete using lime stone crushed fine aggregate(L) exhibited the most favorable fluidity due to grain shape and particle distribution, and next was blending aggregate miting L and G, blending aggregate mixing L and N, granite crushed fine aggregate(G), natural fine aggregate(N) in an order. Concrete using N had the highest air content and L was the smallest value because of the effective filling performance by continuos particle distribution. Compressive, tensile and flexural strength of all concrete using L had the highest value due to the smallest value of air content. It is also found that concrete using L resulted in decrease of drying shrinkage length change ratio.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.73-78
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• 2001

Portland cement concrete is made with coarse aggregate, fine aggregate, portland cement, water and, in some cases, selected chemical admixtures such as air-entraining agents, water reducer, superplasticizer, and so on, and mineral admixtures such as fly ash, silica fume, slags, etc. Typically, in the concrete, the coarse aggregate and fine aggregate will occupy approximately 80 percent of the total volume of the final mix. Therefore, the coarse and fine aggregates affect to the properties of the portland cement concrete. As the natural sands are drained, it is necessary and economical to utilize crushed sands(manufactured fine aggregate). It is reported that crushed sands differ from natural sands in gradation, particle shape and texture, and the micro fines in the crushed sands affect to the quality of the portland cement concrete. Therefore, the purpose of this paper is to investigate the characteristics of fresh and hardened concrete with high content of micro fines. This study provides firm data for the use of crushed sands with higher micro fines.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.127-131
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• 2009

The purpose of this study is to provide fundamental data on chloride diffusion from lightweight aggregate concrete by utilizing crushed stone-powder. Accordingly, the study performed experiments using concrete aggregates of Crushed Aggregate (CG), Single-sized Lightweight Aggregate (SLG), Continuous Graded Lightweight Aggregate (CLG), and using water-binder ratio of 0.4, 0.5, 0.6, and using binder of FA and BFS. The chloride diffusion coefficient is calculated after experiment based on NT BUILD 492. Diffusion coefficient of SLG and CLG were little bit higher than CG Concrete, but the difference is meaningless. Also, chloride diffusion coefficient indicates that it is highly affected by water-binder ratio, and it decreases with the decrease in water-binder ratio. The admixture substitution indicates decrease only with water-binder ratio of 0.4 for FA15% case, but admixture substitution indicates decrease with all levels of ratio for FA10 + BFS20% which means more appropriate. According to the analysis result of chloride diffusion from lightweight aggregate concrete, crushed stone-powder utilized lightweight aggregate concrete indicates higher chloride diffusion coefficient than CG concrete, which is not a significant difference, and can improve resistance through water-binder ratio and admixture substitution.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.186-191
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• 1996

The recycled aggregate obtained from the recycled concrete may be used in road construction as crushed aggregate. The properties of recycled aggregate are reached to the values in accordance with specification for the subbase layer of the road construction. However, for the base layer of road construction, the mixtures of recycled aggregate and crushed aggregate have to be used in order to satisfy the specification. In the Batch Leaching Test the recycled aggregate has lower content of heavy matal and organic matter than those written in environmental pollution law. So it does not occur the environmental pollution.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.233-238
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• 1998

For substitution for crushed sand, high strength aggregate for cement and concrete using coal ash as a main material was prepared and then compared its physical properties with those of crushed sand. Effect of mix proportion change of raw materials on the property of aggregate was checked. On the basis of these experimental results we are going to comprehend the reutilization of coal ash and utilize a basic data for judging possibility the substitution of crushed sand.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.13-18
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• 2003

The concrete structure can be easily damaged due to alkali-aggregate reaction. The alkali-aggregate reaction is a reaction between the alkalies(K or Na) in cement and an unstable mineral of the aggregates. There are several test methods to identify alkali reactivity of aggregates. In general, crushed stones are tested by petrographic examination, chemical method and 모르타르 바 method. This study tested alkali-aggregate reactivity of crushed stones that has different rock types such as granitic, volcanic, metamorphic and sedimentary rocks. Samples are collected from 12 local aggregate production companies. Alkali-reactivity of various rock types was evaluated by using ASTM C 227 and C 1260, and compared the test results of two test methods.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.71-72
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• 2015

As this study is the one related to the ultra high strength concrete essentially used for high rise buildings, it has analyzed on the flowability of ultra high strength concrete according to the variation of coarse aggregate and fine aggregate. The coarse aggregate was planned as two types including Granite Aggregate (GA) and crushed coarse Limestone Aggregate (LA) while fine aggregate was planned as four types including Sea Sand (SS), Limestone Crushed Fine Aggregates (LFA), Electric Arc Furnace Oxidizing Slag Aggregates (EFA) and Crushed Sand (CS) to perform experiment with a total of eight variables. As a result of analyzing slump flow, 500mm concentration time, U-Box and L-Flow, etc. among the characteristics of fresh concrete, a mix using LA+LFA is determined to show high flowability in case of applying ultra high strength concrete.

• Journal of Advanced Engineering and Technology
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• v.11 no.4
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• pp.295-301
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• 2018

In this study, freezing-thawing resistance of concrete using steel slag as coarse aggregate(steel slag concrete) from Gwangyang Iron Co. was estimated to offer basic data for utilization of much more steel slag. Freezing-thawing test of concrete using crushed stone as coarse aggregate(crushed stone concrete) whose compressive strength and air contents are as close as possible to those of the steel slag concrete was performed. Because they are main two factors that affect of freezing-thawing resistance. The test was carried out up to 400 cycles according to KS F 2456. The compressive strength and weight of two concretes were measured and compared. As a result, the freezing-thawing resistance of steel slag concrete curing in water was almost the same with that of crushed stone concrete. But the resistance of steel slag concrete curing in air dry condition was weaker than that of crushed stone concrete. Also, the steel slag concrete which has more than 60% of W/C ratio showed much more surface degradation when compared to crushed stone concrete.