• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.2
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• pp.109-114
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• 2015

Recently, numerous studies were dedicated on the HVFA concrete using high volume CCPs. In initial studies, main topics are dependent on material properties of HVFA concrete, but several studies were dedicated on the structural behavior of HVFA concrete such as elasticity modulus, stress-strain relationship and structural behavior nowadays. Therefore, in this paper, on the basis of recent studies on the structural behavior, 2 large-scale test members were manufactured with 7.5m span length and fly ash replacement ratio 50%, concrete compressive strength 50MPa in order to apply to the practical structure and evaluate possibility of application. From the test results, although there were small differences between test results and existing research results on the stress-strain relationship, the application to practical structure is not hard. In flexural test, as the produced pattern of displacement and strain were similar to those of general concrete without fly ash, the difference between 50% fly ash concrete and general concrete is very small. And the concrete shear strength obtained by test was similar to that of design code, so existing design code will be also able to apply.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.375-381
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• 2017

Recently, due to the increasing of interest about the eco-friendly concrete, it is being increased to use concretes containing by-products of industry such as fly ash, ground granulated blast furnace slag, silica fume, and etc. Especially, these are well known for improving the resistance to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance to corrosion of reinforcement and critical chloride content of high volume fly ash concrete(HVFAC) which is replaced with fly ash for approximately 50% cement content. For this purpose, corrosion monitoring of reinforcement by half cell potential method was carried out for the cylindrical test specimens that the upper of reinforcement in concrete was exposed to detect the time of corrosion initiation for reinforcement. It was observed from the test result that the the time of corrosion initiation for reinforcement of HVFAC by the accelerated corrosion tests increased 1.2~1.3 times than plain concrete and the critical chloride contents of plain concrete and HVFAC were found to range $0.80{\sim}1.20kg/m^3$, $0.89{\sim}1.60kg/m^3$, respectively.

• International Journal of Concrete Structures and Materials
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• v.7 no.2
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• pp.155-163
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• 2013

The use of sustainable technologies such as supplementary cementitious materials (SCMs), and/or recycled materials is expected to positively affect the performance of concrete mixtures. However, it is imperative to qualify and implement such mixtures in practice, if the required specifications of their intended application are met. This paper presents the results of a laboratory investigation of self-consolidating concrete (SCC) containing sustainable technologies. Twelve mixes were prepared with different combinations of fly ash, slag, and recycled asphalt pavement (RAP). Fresh and hardened concrete properties were measured, as expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Analysis of the experimental data indicated that inclusion of RAP not only reduces the ultimate strength, but it also affected the compressive strength development rate. The addition of RAP to mixes showed a consistent effect, with a drop in strength after 3, 14, and 28 days as the RAP content increased from 0 to 50 %. However, most of the mixes satisfied SCC fresh properties requirements, including mixes with up to 50 % RAP. Moreover, several mixes satisfied compressive strength requirement for pavements and bridges, those mixes included relatively high percentages of SCMs and RAP.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.67-69
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• 2012

This paper is to investigate the effect of waste oil on the fundamental properties of high volume fly ash concrete depending on W/B and waste oil contents. Test results reveals that the use of waste oil resulted in an increase of slump and a decrease of air contents due to the presence of emulsion in waste oil. And it is found that the addition of waste oil does not affect the strength development of the concrete significantly.

• Journal of the Korean Society of Safety
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• v.25 no.5
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• pp.39-43
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• 2010

The surfacing of bridge-decks are object to secure trafficability and to protect bridge face from impact load of traffic volume and other external conditions. But the deformation of pavements and cracks happen due to the damage of the bridge-decks surfacing from the increase of the traffic, short maintenance period and continuous vibration of bridge. This test is to make the 3-type high performance concrete that has different mixing ratio and is added the blast furnace slag, fly ash and silica respectively, and to compare 3-type high performance concrete of normal high strength concrete of $400kgf/cm^2$ strength through the static loading test and fatigue test. And test specimen is united floor slab and pavement for the durability of bridge.

• Advances in concrete construction
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• v.11 no.3
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• pp.183-192
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• 2021

Due to economic and environmental benefits, increasing the substitution ratio of ordinary cement by industry by-products like fly ash (FA) is one of the best approaches to reduce the impact of the concrete industry on the environment. However, as the substitution rate of FA increases, it will have an adverse impact on the performance of cement-based materials, so the actual substitution rate of FA is limited to around 10-30%. Therefore, in order to increase the early-age strength of high replacement (30-70%) low-calcium ultrafine FA blended cement paste, sodium sulfate and calcium sulfate dihydrate were used to improve the reactivity of FA. The results show that sodium sulfate has a significant enhancement effect on the strength of the composite pastes in the early and late ages, while calcium sulfate dihydrate has only a slight effect in the late ages. The addition of sodium sulfate in the cement-FA blended system can enhance the gain rate of non-evaporation water, and can decrease the Ca(OH)2 content. In addition, when the sulfate chemical activators are added, the ettringite content increases, and the surface of the FA is dissolved and hydrated.

• Magazine of RCR
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• v.8 no.2
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• pp.13-16
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• 2013

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.737-740
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• 2008

This study, with the purpose for early quality improvement of concrete which used large quantity of fly ash, changed various admixture material type and reviewed the basic characteristics. First off, the flow overall was highest when polycarb onic Acid high early strength AE water reducing agent was displaced, while air amount satisfied target level only in the case of plain, and setting time was shown best by getting 30 more minutes than plain and about 3 more hours than conventional when KOH is displaced. Compressive strength was shown best at age 1 day and 3 days when KOH was displaced, and at age 28 days when fine particle cement was displaced. By and large, this study concludes that concrete quality improvement admixture material that used large amount of fly ash showed worse effects than plain, therefore it is determined that there need be more study for development of concrete early quality improvement admixture material that used large amount of fly ash.

• Advances in concrete construction
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• v.3 no.4
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• pp.317-331
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• 2015

This paper presents the effect of different micro-silica (MS) contents of 5, 10 and 15 wt.% as partial replacement of cement on mechanical and durability properties of high volume fly ash - recycled aggregate concretes (HVFA-RAC) containing 50% class F fly ash (FA) and 35% recycled coarse aggregate (RCA) as partial replacement of cement and natural coarse aggregate (NCA), respectively. The measured mechanical and durability properties are compressive strength, indirect tensile strength, elastic modulus, drying shrinkage, water sorptivity and chloride permeability. The effects of different curing ages of 7, 28, 56 and 91 days on above properties are also considered in this study. The results show that the addition of MS up to 10% improved the early age (7 days) strength properties of HVFA-RAC, however, at later ages (e.g. 28-91 days) the above mechanical properties are improved for all MS contents. The 5% MS exhibited the best performance among all MS contents for all mechanical properties of HVFA-RAC. In the case of measured durability properties, mix results are obtained, where 10% and 5% MS exhibited the lowest sorptivity and drying shrinkage, respectively at all ages. However, in the case of chloride ion permeability a decreasing trend is observed with increase in MS contents and curing ages. Strong correlations of indirect tensile strength and modulus of elasticity with square root of compressive strength are also observed in HVFA-RAC. Nevertheless, it is established in this study that MS contributes to the sustainability of HVFA-RAC significantly by improving the mechanical and durability properties of concrete containing 50%less cement and 35% less natural coarse aggregates.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.2
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• pp.93-100
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• 2013

A variety of researches on the concrete with high volume mineral admixture have increased in recent years. In fact, it is very important to find appropriate replacement ratio of concrete with high volume mineral admixture in order to apply in the field. In this study, compressive strength according to fly ash and blast furnace slag replacement ratio as well as curing temperature was measured in the conditions of obtaining the same workability in order to examine the characteristics of concrete with high volume mineral admixture. In conclusion, it was found that the compressive strength at the age of 3 days decreased by 1.4MPa and the compressive strength at the age of 28 days decreased by 3.8MPa when the fly ash replacement ratio increased by 10%. Also, it was found that the compressive strength at the age of 3 days decreased by 1.0MPa and the compressive strength at the age of 28 days decreased by 0.9MPa when the blast furnace slag replacement ratio increased by 10%. Through the tests, we obtained the basic data for developing the future research on the concrete with high volume mineral admixture for housing structure.