• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.465-466
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• 2010

In this paper, an integrated system is proposed which can evaluate both the early-age properties and durability performance of concrete structures. This integrated system starts with a hydration model which considers both Portland cement hydration and chemical reactions of supplementary cementing materials (SCM). Based on the degree of hydration of cement and mineral admixtures, the amount of reaction products, the early age heat evolution, chemically bound water, porosity, the early age short-term mechanical behaviors, shrinkage and early-age creep are evaluated as a function of curing age and curing conditions. Furthermore, the durability aspect, such as carbonation of blended concrete and chloride attack, are evaluated considering both the material properties and surrounding environments. The prediction results are verified through experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.301-302
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• 2010

The purpose of this study was to get basic information of using high blaine reject ash as a mineral admixtures in cement or concrete system. Compressive strength of mortar and rheological properties of slag cement with fly ash or high blaine reject ash($6,400cm^2/g$) were investigated.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.6
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• pp.90-98
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• 2002

Recently the use of the antiwashout underwater concrete with the antiwashout admixture is increased considerably. Antiwashout underwater concrete is quite different in concept from conventional underwater concrete. By mixing an antiwashout admixture with concrete, the viscosity of the concrete is increased and its resistance to segregation under the washing action of water is enhanced. The aim of this research is to evaluate the fundamental characteristics and permeability of antiwashout underwater concrete with fly ash and blast-furnace slag. Test Results of antiwashout underwater concrete with fly ash and blast-furnace slag fluence can provide its excellent fundamental characteristics and resistance of permeability.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.9-12
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• 2005

In this study, to investigate shrinkage and cracking behavior of 120MPa UHSC, free and restrained drying shrinkage test were performed. Three strength levels(50MPa, 80MPa, 120MPa) were used and the effect of mineral admixtures(fly ash, slag) on free and restrained shrinkage was investigated. From comparing the result of pin -penetration test with the result of ring test, Time-Zero was determined as initial set. Shrinkage test results show that autogenous shrinkage of UHSC was much higher than that of HSC, VHSC and fly ash delayed cracking age in UHSC by decreasing autogenous shrinkage. Additional free concrete rings(with restraint removed) were also tested to check the influence of the geometry of the specimens on free shrinkage. And then the relationship between free shrinkage and restrained shrinkage was investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.313-316
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• 2005

In the recent design of high ductile fiber-reinforced cementitious composite ECC, which exhibits tensile strain-hardening behavior in the hardened state, optimizing both processing mechanical properties for specific applications is critical. This study introduced a method to develop useful ECCs in field, which possess the different fluid properties to facilitate diverse types of processing (i.e., self-consolidating or spray processing). Control of rheological modulation was regarded as a key factor to allow the performance of the desired processing, while retaining the ductile material properties. To control the rheological properties of the composite, we first determined basic ECC compositon, which is based on micromechanics and steady-state cracking theory. The stability and consequent viscosity of suspensions were, then, mediated by optimizing dosages of chemical and mineral admixtures. The rheological properties altered by this approach were revealed to be effective in obtaining ECC hardened properties, allowing us to readily achieve the desired function of the fresh ECC.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.345-348
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• 2005

This paper presents the result of adiabetic temperature rise and fundamental properties of concrete combining admixtures. According to results, difference of setting time with I5.5hours is observed between S-P and R-F30 mixture. Based on the adiabetic temperature rise test, 8$^{circ}C$of heat producted occurs between E-P and R-F30 mixture. is applied to estimate the temperature rising under adiabetic curing condition, which exhibits closer consistency with tested value. The function mentioned above can account for the effect of dormant period in hydration process at early stage on hydration heat production. It reveals that the consideration of placing layer based on the mixture adjustment(E-P mixture at top layer and R-F30 mixture at bottom layer) in mass concreting will contribute to reduce hydration heat as well as alleviate tensile stress discrepancy between placing layer.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.381-384
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• 2005

The purpose of this study reutilization of waste fine tailing (FT) as admixture for cement and concrete. Various admixtures were made of Fine tailings and 2 Types of OPC, fly-ash and blast furnace slag. Cement mortars and concrete with FT are tested for fluidity and compressive strength. Also, the hydration reactivity of cement mortar with FT was examined by XRD and SEM morphology analysis. This work showed that the waste fine tailing could be effectively utilized as replacement materials of cement without any decrease in the strength if we can control the blaine of materials like cement, blast furnace slag and fly ash.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.139-140
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• 2019

In this study, we considered the influence on segregation resistance at the time of substitution of FA and BS, which are substance admixtures of high fluidity concrete. According to the research results, EIS, which is an index of segregation in high fluidity concrete replacement, showed a low value, and the composition also showed a higher value than OPC. Therefore, it is confirmed that the resistance to segregation at the time of admixture replacement of high fluidity concrete is improved.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.48-49
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• 2015

High-calcium fly ash (FH) is widely used as mineral admixtures in concrete industry. In this paper, a hydration model is proposed to describe the hydration of high-calcium fly ash blended-cement. This model takes into account the hydration reaction of cement, the chemical reaction of fly ash, and reaction of free CaO in fly ash. Using the proposed model, the development of compressive strength of FH blended concrete is predicted using the amount of calcium silicate hydrate (CSH). The agreement between simulation and experimental results proves that the new model is quite effective.

• Journal of the Korea Institute of Building Construction
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• v.3 no.3
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• pp.73-81
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• 2003

In this paper, salt damage resistance of high durable concrete was tested. High durable concrete was made by using low water cement ratio, chemical admixture called super-durable admixture and mineral admixtures such as fly-ash, ground granulated blast-furnace slag, silica fume. Two kinds of salt damage resistance test were carried out. One method is chloride ion penetration test(ASTM C1202), and the other one is depth of chloride penetration test in saline solution. Test results were as followers: 1) The depth of chloride ion penetration increased exponentially as water cement ratio was increased and time passed. 2) Super-durable admixture had little effect on the improvement of salt damage resistance of concrete. 3) Silica fume and ground granulated blast-furnace slag were effective on salt damage resistance because of pozzolanic reaction, but fly-ash had a little effect.