• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.305-312
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• 2017

To evaluate the reliability of fly ash quality supplied to ready-mixed concrete plant using mass cylinder and hydrometer, in this research, the correlationship between the fly ash properties provided from certification and density measurement with suspension was evaluated. As a result, the reliability of the certification, except fineness and loss on ignition, all properties had a discord. Additionally, in the case of density, fineness, and L.O.I, the relation with the density measured using hydrometer showed high correlation, especially fineness was strongly related with the density measured using hydrometer. Furthermore, according to the comparative analysis with previous research, the fly ash used in this research was similar measurement with raw powder without any refining process, it is considered that the constant error of blaine test or using raw ash sample as a fly ash. In current standard regarding fly ash, the fineness range of class 2 can be changed from $3,000-4,500cm^2/g$ to $3,500-4,500cm^2/g$ for improved quality of fly ash in fineness aspect.

• Computers and Concrete
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• v.34 no.1
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• pp.33-48
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• 2024

This paper presents the detailed experimental and analytical investigation on the evolution of static (E_s) and dynamic modulus of elasticity (E_d) of concrete having 0%, 35%, and 50% FA used as partial cement replacement. Destructive and non-destructive tests were conducted on cylindrical specimens to evaluate the compressive strength and MoE of concrete in compression at the age of 28, 56, 90, and 150 days for all mixes. Experimental results show that the concrete having 35% FA achieved compressive strength and MoE similar to plain concrete at the age of 90 days, while 50% FA concrete attained satisfactory compressive strength and MoE at the age of 150 days. The comprehensive statistical analysis has been carried out in two ways on the basis of the experimental results. Firstly, the 28-day crushing strength of plain concrete in compression was used to design the models for the prediction of E_s and E_d of fly ash concrete at any age and percentage replacement of FA. Secondly, using the values of UPV and RHN, models have been developed to predict the age or time-dependent E_s and E_d of fly ash concrete. These models will be helpful in assessing the E_s and E_d of fly ash concrete without knowing the 28-day crushing strength of plain concrete in compression in the laboratory. Hence, the suggested models in the present study will be beneficial in conducting the health assessment of fly ash based concrete structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.117-125
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• 2017

The role of fly ash in concrete become impotent with finding the characteristics of fly ash in which it is used as cement replacement material. In this paper, corrosion test results obtained by two test methods such as the long-term exposure corrosion test and the accelerated corrosion test method, were compared to investigated the corrosion resistance between fly ash concrete and normal concrete. Corrosion initiation time was measured in two types of concrete, i.e., one mixed with fly ash(FA) and the other without admixture(OPC). The accelerated corrosion test was carried out by four case, i.e., two samples is a cyclic drying-wetting method combined without carbonation(case 1) and combined with carbonation(case 2), and the other two samples is a artificial seawater ponding test method combined without carbonation(case 3) and combined with carbonation(case 4). Whether corrosion occurs, it was measures using half-cell potential method. The ponding test combined without carbonation was most effective in accelerating corrosion time of steel bars. The results indicated that the corrosion of rebar embedded in concrete occurred according to the order of OPC, FA. The delay relative ratio of corrosion obtained by corrosion initiation time between FA and OPC is 1.04 to 1.27. Consequently, fly ash concrete as the age increases its corrosion resistance was improved compared with OPC concrete.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.386-391
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• 2009

The purpose of this study is to elucidate the adsorption properties of fly ash (FA)-derived zeolites A and X for the divalent cationic herbicides, paraquat and diquat. Their adsorption isotherms were well fitted to the Langmuir equation, indicating that adsorption mainly occurred on the crystal surface. FA-zeolite X showed a higher adsorption capacity than that of FA-zeolite A due to wide pore window size in spite of its low CEC. The equilibrium adsorption increased with increasing the reaction temperature because of the enhanced molecule activity and the thermal expansion of zeolite pore windows. Overall, these results demonstrated that the FA-zeolite synthesized from fly ash could be used as a low-cost mineral adsorbent for the removal of environmental cationic organic pollutants from the aqueous solution.

• Advances in concrete construction
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• v.3 no.1
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• pp.55-69
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• 2015

Tailing Material (TM) and Fly Ash (FA) are obtained as waste products from the mining and thermal industries. Studies were carried out to explore the possibility of utilizing TM as a part replacement to fine aggregate and FA as a part replacement to cement, in concrete mixes. The effect of replacing fine aggregate by TM and cement by FA on the standard sized specimen for compressive strength, split tensile strength, and flexural strengths are evaluated in this study. The concrete mix of M40 grade was adopted with water cement ratio equal to 0.40. Concrete mix with 35% TM and 65% natural sand (TM35/S65) has shown superior performance in strength as against (TM0/S100, TM30/S70, TM40/S60, TM50/S50, and TM60/S40). For this composition, studies were performed to propose the optimal replacement of Ordinary Portland Cement (OPC) by FA (Replacement levels studied were 20%, 30%, 40% and 50%). Replacement level of 20% OPC by FA, has shown about 0-5% more compressive strength as against the control mix, for both 28 day and 56 days of water curing. Interestingly results of split tensile and flexural strengths for 20% OPC replaced by FA, have shown strengths equal to that of no replacement (control mix).

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.53-56
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• 2006

To develop more durable concrete deck, performance characteristic test of HPC(High Performance Concrete) mixtures was carried out. The parameters used in this project were ; the mineral admixture details were 4 types such as ordinary portland cement(OPC), 20% fly ash (FA), 20% fly ash and 4% silica fume(FS), and 40% ground granulated blast-furnace slag(BS). Their design compressive strengths were 27MPa and 35MPa respectively. The results showed the compressive strength of concrete did not much affect the durability of concrete. HPC with blast-furnace slag(BS) showed the good durability but was prone to crack. HPC with fly ash(FA) or with fly ash and silica fume(FS) had the good durability and crack resistance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.112-113
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• 2019

Recently, supplementary cementitious materials such as blast-furnace slag, fly ash and silica fume have been widely used as substitutes for cementitious materials. In this study, the deformation behavior of compressive loading of C₃S paste with 50% fly ash was analyzed by X-ray scattering data and pair distribution function analysis. The obtained results were compared with 131-day-old pure C₃S paste. The Ca(OH)₂ of the C₃S-FA paste showed almost complete elastic behavior, consistent with the deformation behavior of the r-range of 20 to 40, and the C-S-H phase contributed to the range of PDF r-range of less than 20. In addition, C-S-H of C₃S-FA showed greater deformation resistance than C₃S paste.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.525-532
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• 2014

It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only, however, it is necessary to perform the research about structural shear behavior. Therefore, in this paper, 27 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35%, 50%, concrete compressive strength 20, 40, 60 MPa and 3 shear stirrups amounts. 27 test members were tested for shear behavior. From the test results, there were no differences between 35%, 50% high volume fly ash cement concrete and ordinary concrete without fly ash (FA=0%).

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.323-329
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• 2014

It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only, however, it is necessary to perform the researches about elasticity modulus, stress-strain relationship and structural behavior. Therefore, in this paper, 18 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35, 50%, concrete compressive strength 20, 40, 60 MPa and 2 tensile steel ratio. 18 test members were tested for flexural behavior. From the test results, there were no differences between 35, 50% high volume fly ash cement concrete and ordinary concrete without fly ash(FA=0%).

• Geotechnical Engineering
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• v.12 no.1
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• pp.73-86
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• 1996

In this study, the possibility of the utilization of coal ash as earthwork materials is investigated. For this purpose, some laboratory experiments were carried out. The samples used in these tests are fly ash(FA), bottom ash(BA), coal ash dropped into ash pond(FA:BA=8:2), and mixed coal ash(FA:BA=5:5), which were discharged as a by-product at Yong-Yeul thermoelectric power plant, and general road filling materials. And for the deformation analysis of coal ash reclamation ground, several hyperbolic model parameters were determined by triaxial compression test. As a result of this study, coal ash has excellent engineering properties such as strength parameters comparing with general soils of the same grain size, especially in case of being used as backfill materials and reclamation materials on soft ground, and coal ash is superior to general earthwork materials in engineering properties becasuse of self hardening behaveiour, light weight property, etc.