• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.435-438
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• 2005

The effect of content of reactive aggregate on alkali-silica reaction was investigated through the ASTM C 1260 method. The replacement proportions of fine aggregate by reactive aggregate were 25, 50, 75 and $100\%$, respectively. Reactive aggregate and fine aggregate(non-reactive aggregate) used are a metamorphic rock and andesite rock, respectively. The results indicate that the mortar-bar containing $25\%$ replacement of fine aggregate by reactive aggregate shows the lowest expansion but expansion in excess of $0.1\%$ at 16 days, which can distinguished between deleterious and potentially reactive. Although content of reactive aggregate is a small amount, it can cause detrimental expansion due to alkali-silica reaction.

• International Journal of Concrete Structures and Materials
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• 제4권2호
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• pp.119-125
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• 2010

In this study, the effects of the fineness modulus of reactive aggregate on ASR expansion and ASR products have been investigated. The reactive aggregate used was metamorphic aggregate originated from Korea. ASR tests were conducted according to accelerated mortar bar test. The morphology and chemical composition of products formed in mortar bars, 5 years after the mortar bar test had been performed, were studied by scanning electron microscopy equipped with energy dispersive spectroscopy. Test results indicated that ASR expansion of mortar bars decrease in linear proportion to the fineness modulus of reactive aggregate. SEM images indicated that mortar bars showed reactive products formed in cement paste, within air voids and within cracks through particles except for the mortar bar with the fineness modulus of 3.25. The EDS analysis of the reactive products showed presence of silica, calcium and sodium, typical of ASR product composition.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.137-140
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• 1996

The deterioration of concrete due to alkali-aggregate reaction is dependent on the total alkali content per unit volume of concrete. It was reported that the expansion of high alkali concrete with the reactive aggregate increased easily due to high alkali of concrete with the reactive aggregate increased easily. And it has been confirmed that the addition of pozzolanic material prevents the concrete with reactive aggregate from deterioration caused by alkali-aggregate reaction. It is the aim of this study to provide the fundamental data on the possibility of alkali-aggregate reaction of high strength concrete and its preventing and repair technic.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.363-368
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• 2000

This paper is an introduction of pessimum program for the identification of alkali-silica reaction of alkali-aggregate reaction which is known as one of a major factor of concrete deterioration. A series of gel-pat testing program was undertaken to observe the reactivity of potentially alkali-silica reactive concrete aggregates which were found to be reactive by previous petrographic examination (ASTM C 295). And then a pessimum program was performed in accordance with mortar-bar test method (ASTM C 227) with different percentage of those reactive components included in the fine aggregate source to determine the pessimum quantity. Chert and quartzite were found to be major components of reactive mineral/rock, and the pessimum condition for chert was about 3%, even though the test was performed with up to 25% of the component. In the case of quartzite, however, the mortar-bar expansion appeared to be directly proportional to the amount of quartzite sample with increasing tested quantity up to 35%. Both of the expansion results were well 3 and 6 month specified maximum limitation of 0.05% and of 0.1% respectively.

• Computers and Concrete
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• 제16권1호
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• pp.37-48
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• 2015

Alkali aggregate reaction affects numerous civil engineering structures and causes irreversible expansion and cracking. This work aims at developing model to predict the potential expansion of concrete containing alkali-reactive aggregates. First, the paper presents the experimental results concerning the influence of particle size of an alkali-reactive aggregate on mortar expansion studied at 0.15-0.80 mm, 1.25-2.50 mm and 2.5-5.0 mm size fractions and gives data necessary for model development. Results show that no expansion was measured on the mortars using small particles (0.15-0.80 mm) while the particles (1.25-2.50 mm) gave the largest expansions. Finally, model is proposed to simulate the experimental results by studying correlations between the measured expansions and the size of aggregates and to calculate the thickness of the porous zone necessary to take again all the volume of the gel created by this chemical reaction.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.549-554
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• 2001

The authors have proposed that waste glass, which is crushed to pieces, can be used as a concrete aggregate. At the present time, recycled-glass concrete is used for sidewalk concrete blocks and pavement as glass is ornamental. However, in cases where recycled-glass concrete is used for structural concrete, strength and durability are required as structural concrete is exposed to the weather. Glass that is used generally is a mixture of SiO$_2$, Na$_2$O and CaO. SiO$_2$is the most likely cause of alkali-aggregate reaction when waste glass was used for concrete aggregate. In this study, an alkali-aggregate reaction test that is one of the important tests related to durability of aggregate was carried out far discussion of utilization of waste glass for concrete aggregate. From the results of the tests, it is found that glass is a reactive aggregate. The pessimum proportion of glass is about 75%. Then the cases of using fly ash, blast furnace slag and artificial zeolite for admixture materials were also examined for the purpose of prevention of alkali-aggregate reaction. from the results of the test, it was found that using them is an effective way to prevent alkali-aggregate reaction. The compressive strength in the cases of using admixture materials is larger than that without admixture materials.

• 한국건축시공학회지
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• 제4권1호
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• pp.141-146
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• 2004

1) As a result of compressive strength experiment, rupture compressive strength showed more increases in specimens of 15% and 20% of Cockle shells in those of non-mixture. Comparing compressive strength between no-mixed Specimens and Specimens of containing Cockle shells, Specimens containing Cockle shells showed higher strength in 60 days and 90 days of age, and as ark Cockle is contained and age is elapsed, compressive strength is also increased In addition, estimation of compressive strength by reactive hardness in concrete using Cockle shells as aggregate shows low reliability. 2) As a result of experimenting compressive strength after heating, Specimens containing Cockle shells and non-mixed Specimens showed similar strength at $200^{\circ}C$, but compressive strength was lowered as content of Cockle shells increased at over $400^{\circ}C$ and heating temperature was higher. It is because Cockle shells was fired by heat and then its adhesion and bonding capacity were lost. 3) To sum up the above experimental results, it is found that using splitted Cockle shells as aggregate for concrete by 10%~20% showed the same or higher compressive strength and shear strength as concretes using general aggregate and it can be used as substitute aggregate of concrete. It is considered that for future use of splitted Cockle shells as substitute concrete aggregate, continuous researches of its durability, applicability and economy are needed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.103-107
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• 1993

The Alkali Aggregate Reaction(AAR), reported first by T. E. Stanton in 1940, is a reaction between certain siliceous aggregate and hydroxyl ions present in the pore fluid of a concrete. The damage of concrete structures, deteriorated by AAR, have been reported since using the crushed stones caused by the exhaustion of natural aggregates. This study was performed to investigate the AAR of crushed stones using chemical analysis, polarization microscope, XRD, chemical method(KS F 2545, ASTM C 289), mortar bar method(KS F 2546, ASTM C 227) and Scanning Electron Microscope(SEM) and Energy Dispersive X-ray Analysis (EDXA) of reaction products by AAR in mortar bar.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.23-24
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• 2020

In this study, effect of surface modification of waste glass for fine aggregates on the mechanical properties and alkali silica reaction of mortar was analyzed. As a result, it was confirmed that the incorporation of waste glass fine aggregate decreases the mechanical properties of the mortar and increase the alkali silica reaction expansion. On the other hand, the surface modification of the waste glass fine aggregate is effective in improving this problem. However, unlike green and brown waste glass, it is judged that an additional experiment to determine the cause is necessary for white waste glass where alkali silica reactive expansion occurs extremely.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.68-71
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• 2013

Reactive Powder Concrete (RPC) is an ultra high strength and high ductility cement-based composite material and has shown some promise as a new generation concrete in construction field. It is characterized by a silica fume-cement mixture with very low water-binder (w/b) ratio and very dense microstructure, which is formed using various powders such as cement, silica fume and very fine quartz sand (0.15~0.4mm) instead of ordinary coarse aggregate. However, the unit weight of cement in RPC is as high as 900~1,000 kg/㎥ due to the use of very fine sand instead of coarse aggregate, and a large volume of relatively expensive silica fume as a high reactivity pozzolan is also used, which is not produced in Korea and thus must be imported. Since the density of RPC has a heavy weight at 2.5~3.0 g/㎤. In this study, the modified RPC was made by the combination of ternary pozzolanic materials such as blast furnace slag and fly ash, silica fume in order to economically and practically feasible for Korea's situation. The fire resistance and structural behavior of the modified RPC exposed to high temperature were investigated.