• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.146-147
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• 2014

In this study, as the resistance of the carbonation for high volume admixture incorporating concrete, coating effect of using refined cooking oil in the surface of high volume admixture incorporating concrete has been tested. The following results could be made as the conclusion. For the fresh concrete, the slump and air content has been identified as satisfying the target range. For the hardened concrete, comparing with specimen of Plain, specimen with coating showed better long age compressive strength. For the carbonation speed, the specimen of FA30 showed highest speed and the specimen of BS60 showed higher speed than specimen of Plain. For all the specimens coated with RCO, as the decrease of capillary pores inside the concrete, the carbonation speed has been obviously decreased and with even better effect than using PEP coating. It could be identified that specimens with coating by RCO showed good effect on refrain the speed of carbonation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.31-36
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• 2008

This study aims to examine the effects of thickness of the concrete members and curing temperature on the properties of low heat concrete through heat of hydration analysis. Type of the members that was analyzed in the experiment is ternary mixture of ordinary portland cement, blast-furnace slag incorporating ratio(20%) and fly ash incorporating ratio(30%), which formed a mat foundation. Thicknesses of the concrete members were 1, 2 and 3(m) and three levels of curing temperatures were 10, 20 and 30(℃). They were applied to analyze the effects on the temperature and thermal cracking index. As a result, for temperature history, temperature difference between the central area and the surface tended to decrease as the thickness of the concrete members get thinner. For the temperature cracking index, on the other hand, the risk of cracking tended to decrease as the curing temperature gets higher and as the thickness gets thinner.

• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.90-93
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• 2008

The oxygen gas behavior in PDP (plasma Display Panel) glass melts doped with sulfate ($SO_4^{-2}$) or blast furnace slag (BFS, $S^{2-}$) or both by means of yttria-stabilized zirconia (YSZ) electrodes was observed after the first fining. The temperature dependence of oxygen equilibrium pressure ($P_{O2}$) in each melt showed typical behavior, namely $P_{O2}$ decreased as temperature decreased. This suggests that an oxidation of $S^{4+}$ to $S^{6+}$ took place. However, the $P_{O2}$-value at constant temperature increased in the following order: BFS$P_{O2}$ of the melt doped with sulfate+BFS was much lower than that of the melt with only sulfate, although only 10% of sulfur was added by the BFS. This behavior can be explained by the redox reaction between sulfide ions in the BFS and dissolved oxygen ions in the melt during the first fining.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.451-459
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• 2012

At the Korea Land and Housing Corporation(LH), concretes with high design strength of 50 MPa and 80 MPa that are composed only of ordinary Portland cement, blast furnace slag, and fly ash are developed. To determine whether the developed high strength concretes have the same properties when they are produced in batch plant(B/P) condition in the ready mixed concrete plant, and as existing high strength concretes, field tests are performed and material properties are evaluated. To investigate the material properties of the high strength concretes before and after pumping, compressive strength, flowability, air content, hydration temperature, pumping and compactability are evaluated. In field tests, before and after pumping, flowability satisfied the relevant criteria. In terms of air content, while it was slightly decreased after pumping, it satisfied the requirements. Hydration temperature criteria were satisfied, and compactability was excellent as well. The study found that the developed ternary high strength concretes have the same properties as existing high strength concretes. They can also be useful for the construction of high-rise buildings, as they are economical.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.4
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• pp.21-27
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• 2011

These materials in architecturally glass or metal have weaknesses such as inadequate insulating quality, combustibility and toxic gases in fires substance. However, Autoclaved Lightweight Concrete(ALC) has excellent thermal insulation properties and seem to possess the superb insulating quality as substitute of existing exterior materials. This research is to compare experimentally to the kind of the strength properties of ALC materials which mixed with blast furnace slag pounder and silica fume. For the purpose of increasing the strength, the plastic states of ALC evaluate the physical characteristics as microstructure and strength according to various specific gravity. According to the quicklime quantity the compressive strength is proportionate depend on the absolute dried specific gravity. When not putting in 10% quicklime, the compressive strength appeared most lowly with 14.0MPa. When putting in the quicklime, the strength appeared higher with 15.1MPa. And strength of specimen containing 2.25% silica fume is 15.6MPa increased 10.3% than reference specimen 14.0MPa.

• Journal of the Korea Concrete Institute
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• v.16 no.2 s.80
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• pp.277-282
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• 2004

In a hardened concrete, diffusion of oxygen, carbon dioxide, aggressive ions, and moisture from the environment to the concrete takes place through the pore network. It is well known that making dense cement matrix enhances the durability of concrete as well as all the characteristics including strength of concrete. In this paper,9 mix concretes with water to cementitious material ratio (40,45, and $50\%$) and replacement ratio of GGBFS (40 and $60\%$ of cement by weight) were studied on the micro-pore structure by mercury intrusion porosimetry and the accelerated chloride diffusion test by potential difference. From the results the average pore diameter and accelerated chloride diffusivity of concrete were ordered NPC > G4C > G6C. It is concluded that there is a good correlation between the average pore diameter and the chloride diffusivity, and the mineral admixtures has a filling effect, which increases the tortuosity of pore and makes large pores finer, on the pore structure of cement matrix due to the latent hydraulic reaction with hydrates of cement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.3
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• pp.240-245
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• 2013

The optimum binder ratio of the low heat mass concrete for LNG tank was evaluated in the present study. Three types of binder such as OPC I, ground granulated blast-furnace slag powder were mixed and were used. Also fine particle cement and activator were used to raise an early age strength development and ground limestone was used to reduce the cost. As a result of the study, mix ratio II (30:30:40) was suitable for Bottom Center and mix ratio III(40:30:30) was suitable for Roof based on compressive strength and semi-adiabatic temperature.

• Advances in concrete construction
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• v.6 no.1
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• pp.29-45
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• 2018

This paper investigates the effect of inclusion of glass fibers on mechanical and fracture properties of binary blend geopolymer concrete produced by using fly ash and ground granulated blast furnace slag. To study the effect of glass fibers, the mix design parameters like binder content, alkaline solution/binder ratio, sodium hydroxide concentration and aggregate grading were kept constant. Four different volume fractions (0.1%, 0.2%, 0.3% and 0.4%) and two different lengths (6 mm, 13 mm) of glass fibers were considered in the present study. Three different notch-depth ratios (0.1, 0.2, and 0.3) were considered for determining the fracture properties. The test results indicated that the addition of glass fibers improved the flexural strength, split tensile strength, fracture energy, critical stress intensity factor and critical crack mouth opening displacement of geopolymer concrete. 13 mm fibers are found to be more effective than 6 mm fibers and the optimum dosage of glass fibers was found to be 0.3% (by volume of concrete). The study shows the enormous potential of glass fiber reinforced geopolymer concrete in structural applications.

• Advances in concrete construction
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• v.6 no.1
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• pp.69-85
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• 2018

In order to provide sufficient stability and resistance against bleeding and segregation during transportation and placing, mineral admixtures are often used in self-compacting concrete mixes (SCC). These fine materials also contribute to reducing the construction cost and the consumption of natural resources. Many studies have confirmed the benefits of these mineral admixtures on properties of SCC in standard curing conditions. However, there are few published reports regarding their effects at elevated curing temperatures. The main objective of this study is to investigate the effect of three different mineral admixtures namely limestone powder (LP), granulated blast furnace slag (GS) and natural pozzolana (PZ) on mechanical properties and porosity of SCC when exposed to different curing temperatures (20, 40, 60 and $80^{\circ}C$). The level of substitution of cement by mineral admixture was fixed at 15%. The results showed that increasing curing temperature causes an improvement in performance at an early age without penalizing its long-term properties. However the temperature of $40^{\circ}C$ is considered the optimal curing temperature to make economical and high performance SCC. On the other hand, GS is the most suitable mineral admixture for SCC under elevated curing temperature.

• Proceedings of the IEEK Conference
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• 2001.10a
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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.