• Journal of the Korea institute for structural maintenance and inspection
• /
• v.8 no.2
• /
• pp.239-246
• /
• 2004

To improve the durability of concrete structure, we usually consider the reduction of water-cement ratio, the increase of concrete cover depth and the use of mineral admixtures. The use of admixtures make concrete more durable and tighten against water in recent papers so it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. Therefore we analyzed the correlation between chloride ion diffusion and physical properties such as compressive strength, void ratio, air permeability of the concrete, and tried to use them as fundamental data for analyzing chloride ion diffusion mechanism of the concrete mixed with mineral admixtures.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.117-120
• /
• 2004

Up to now, many researches have been performed md verified that many properties of concrete can be improved by using mineral admixtures such as blast furnace slag, silica fume, and expansive admixture. But it is not clear whether there is any need for entraining air to make a high strength concrete using expansive admixture and mineral admixtures to insure enough freeze-thaw resistance. this paper presents the strength and durability properties of high strength concrete using expasive admixtures and industrial by-products. It was observed from the test results that very high strength concrete$(W/B=20\%)$ is not needed to be air entrained and high strength concrete$(W/B=30\%)$ using expansive admixture and mineral admixtures is needed to be entrained $2\~4\%$ air.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.709-712
• /
• 2006

It is necessary to develop a new technology for controling thermal cracking by hydration heat according to the increase construction of massive concrete structures, high strength concrete and early strength concrete. Therefore, it was investigated the characteristics of hydration heat generation of low heat concrete using hydration heat reducing admixtures in this study. To investigate the performance of hydration heat reducing admixtures, it was evaluated hydration heat according to the kind and replacement ratio of phase change material series I, II and the way of using hydration heat reducing admixtures in series III.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.261-264
• /
• 2004

In this study, the experiment was carried out to investigate and analyze the strenth properties and flowability of ultra-high strength concrete accroding to types of mineral admixtures and cements. The main experimental variables were water/binder ratio $25.0\%$, water content $160kg/m^3$ and mineral admixtures such as fly ash, silica fume and meta kaolin. According to the test results, the principle conclusions are summarized as follows 1) In case of using admixtures, superplasticizer amount need more than plain concrete. 2) According to kinds of admixtures and cements, the viscosity of concrete show much difference. 3) The autogeneous shrinkage of ultra-high strength concrete is profitable that use admixture, and heat of hydration is desirable that apply considering countermeasure enough in the advance. 4) Meta kaolin is excellent in side but has viscosity enlargement efficiency a little. But, problem estimates that is not to make design strength to and $70N/mm^2$ if use mixing condition with water-binder ratio properly.

• International Journal of Concrete Structures and Materials
• /
• v.7 no.3
• /
• pp.203-214
• /
• 2013

This study investigates quantitative methods for assessment of infrared analysis of concrete admixtures using correlation coefficients by performing IR scans following the ASTM C494/C494M-11 specifications. In order to achieve this goal, numerous IR scans were performed on specimens supplied by the manufacturer from different batches to ensure uniformity and equivalency. These scans were then analyzed to create correlation coefficients for each admixture. The correlation coefficients were used to quantitatively evaluate and interpret IR Scans of job samples. The study focused on 23 most commonly used concrete admixtures by the New Jersey Department of Transportation (NJDOT). They include air-entrainers, accelerators, retarders, water reducers, and other combinations of these admixtures. Their correlation coefficients were established by analyzing a total of 12 scans of each admixture from three different batches supplied by the manufacturer at different time intervals. In order to validate the obtained correlation coefficients and establish a target correlation, job samples were tested and compared to the obtained correlations. The study also evaluated the effects of drying time and using different types of KBr on correlation coefficients.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.299-304
• /
• 2002

This research was to investigate the invasion and diffusion properties of chloride ion on the concrete containing mineral admixtures by the electrically accelerated test. Mineral admixtures selected in mixes were fly-ash, ground granulated blast-furnace slag, silica fume, and meta-kaolin with 3 degrees of replacement ratios. Tang and Nilsson's test method was used to estimate chloride diffusion coefficients of that mixes. As a result, the total current passing charge and the diffusion coefficient of chloride ion were reduced with the use of mineral admixtures and the increase of replacement ratios. In addition, compressive strength was related with diffusion coefficient of chloride ion. Diffusion coefficients of concrete mixed with ground granulated blast-furnace slag showed relatively low value under the range of compressive strength of 400㎏f/㎠.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.281-282
• /
• 2009

The purpose of this experimental research is to investigate the influence of mineral admixtures on the resistance to acid and sulfate. For this purpose, concrete specimens with types of mineral admixtures such as ground granulated blast-furnace slag, fly ash, and silica fume were made for water-binder ratios of 32% and 43%. It was observed from the test result that the resistance against acid and sulfate of the concretes containing mineral admixtures were much better than the case of plain concrete from immersion tests of 182 days.

• International Journal of Highway Engineering
• /
• v.12 no.3
• /
• pp.113-119
• /
• 2010

This study presents experimental findings on the performance of cement concrete pavement incorporating mineral admixtures such as ground granulated blastfurnace slag and silica fume. Flexural strength, compressive strength, charge passed, diffusion coefficient of chloride ions and initial surface absorption of cement concrete pavement incorporating mineral admixtures were periodically measured and the corresponding results were compared to those of plain concrete pavement. As a result, strength behaviors of concrete pavement were dependent on the types of mineral admixtures. However, it was true that incorporation of silica fume had a beneficial effect on compressive strength development. Furthermore, the application of mineral admixtures led to a lower diffusion coefficient of chloride ions compared to plain concrete pavement. Based on the experimental results, the present study would be helpful to design high-performance cement concrete pavement.

• Journal of the Korea Institute of Building Construction
• /
• v.9 no.2
• /
• pp.85-91
• /
• 2009

W/C and unit volume, which significantly affect quality of concrete related to strength and durability, are regulated at below $185kg/m^3$ for regular concrete generally used in standard specification for constructions. The aim of this research is to develop chemical admixture and find out its potential use by identifying characteristics of admixtures added to soft concrete and hardening concrete, of which content ratio of component for each type of admixtures is subject to change in accordance with unit volume within KS' allowable range. Sodium gluconate, polyoxyethylene nonylphenyl ether, poly carboxylic copolymer in slump, which is characteristic of soft concrete, are deemed highly sensitive while there is no air entrainment except for $10\sim70%$ in WE, WR component content ratio and NP. In hardening concrete, strength in general showed higher action in compressive strength and tensile strength than in plain strength. Use of proper AE agent and AE water reducing agent at the same time is deemed to be used as chemical admixtures capable of manufacturing high-quality, high-quantity concrete.

• Structural Engineering and Mechanics
• /
• v.51 no.1
• /
• pp.1-13
• /
• 2014

This paper reports an experimental study into the rheological behaviour of self consolidating concrete (SCC). The investigation aimed at quantifying the impact of the varying amounts of mineral admixtures on the rheology of SCC containing natural sand. Apart from the ordinary Portland cement (OPC), the cementitious materials such as fly ash (FA), ground granulated blast furnace slag (GGBS) and micro-silica (MS) in conjunction with the mineral admixtures were used in different percentages keeping the mix paste volume and flow of concrete constant at higher atmospheric tempterature ($30^{\circ}$ to $40^{\circ}C$). The rheological properties of SCC were investigated using an ICAR rheometer with a four-blade vane. The rheological properties of self-consolidating concrete (SCC) containing different mineral admixtures (MA) were investigated using an ICAR rheometer. The mineral admixtures were fly ash (FA), ground granulated blast furnace slag (GGBS), and micro silica (MS). The results obtained using traditional workability results are compared with those obtained using ICAR rheometer. The instrument ICAR (International Center for Aggregate Research) rheometer employed in the present study for evaluating the rhelogical behaviour of the SCC is found to detect systematic changes in workability, cementitious materials, successfully. It can be concluded that the rheology and the slump flow tests can be concurrently used for predicting the flow behaviours of SCC made with different cementitious materials.