• Computers and Concrete
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• v.4 no.6
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• pp.425-436
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• 2007

This study is mainly focused on applying Fuller's ideal gradation curve to theoretically design blended ratio of all solid materials of a reactive powder mortar (RPM), also known as reactive powder concrete (RPC), with the aid of error function, and then to study the effect of fly ash/slag on the performance of RPM. The solid particle is assumed to be spherical particles. Then, the void volume of paste ($V_{\nu}$) and the paste content with specific quality can be obtained. As conclusion, under Fuller's ideal grading curve, the amount of fly ash/slag mixture is higher than that with silica fume along due to it better filled the void within solid particle and obtains higher packing density.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.325-328
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• 2006

Recently, repair mortars have been mainly used for repairing old concrete structures. In this study, a new repair mortar including shotcrete admixture, slag, silica fume, sulphate and calcium carbonate, was developed for repairing shotcrete layer and the fresh properties and mechanical characteristics of the repair mortar was measured, Test results showed that the shortcrete admixture and other additives reduce the final setting time from about 7 hours to within 20 minutes and increase very early strength and stiffness (within 5 hours after cast).

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.505-508
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• 2003

The rheological properties of cement paste system mixed with mineral admixture for the purpose of increasing the strength and improving durability and rheology of concrete were investigated. The results were as follows: The rheological properties of one-ingredient paste system were improved with increasing the dosage of superplasticizer. For two-ingredients paste system, increasing the replacement rate of BFS(blast furnace slag) and FA(fly ash), the yield value and plastic viscosity were decreased compared with non-replacement. In the OPC(ordinary portland cement)-SF(silica fume) system, increasing the replacement rate of SF, the plastic viscosity and yield value increased linearly. In three-ingredients paste system, both OPC-BFS-SF and OPC-FA-SF system, the rheological properties were improved compared with the only replacement of SF. Both two- and three- ingredients paste system, the rheological properties using BFS were improved more than FA.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.74-77
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• 2003

This paper investigated the apparent chloride diffusivity of various concretes. Ten mixtures of concrete were initially prepared and tested to estimate diffusion property. The penetration depth and concentration of chloride ion were examined at the same water-binder ration. The binders were composed of normal portland cement, fly ash, ground granulated blast-furnace slag, and silica fume. From the results, it was concluded that using the mineral admixtures had a filling effect on the pore structure of cements matrix due to those pozzoanic reaction with the hydrates of cement, which increases the tortuosity of pore and makes large pore finer. And diffusivity of chloride is following: NPC100 > F10N90 > F30N70 > F20N80 > F20S05 > G30N70 > F10S05 > G30S05 > G30F15 > G50N50.

• Smart Structures and Systems
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• v.19 no.3
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• pp.323-333
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• 2017

Waste materials in concrete have been considered as one of the most important issues by the authorities, policy makers and researchers to maintain engineering serviceability in terms of economy, durability and sustainability. Therefore, evaluation and selection of waste materials with respect to multi criteria decision making (MCDM) for the construction industry has been gained importance for recovery and reuse. In this paper, Choquet integral based fuzzy approach is proposed for evaluating the most suitable waste materials with respect to compressive strength, tensile strength, flexural strength, compactness, toughness (resistivity for dynamic loads), water absorption and accessibility. On conclusion, waste tyre and silica fume were determined as the most suitable waste materials for concrete production. The obtained results are recommended to assist the authorities on configuring well designed strategies for construction industry with disposal materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1041-1046
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• 2003

The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture (fly ash, silica fume). So, Belite cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.325-328
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• 2004

According to demand the increase of the rate of strength development for rapid constructions and repairs, many efforts have progressed to improve on performance of concrete. The use of regulated set cement helps make it possible to increase the rate of strength development. However it has some problems as like increasing its permeability and accelerate its long-term deterioration caused by internal and external factors. The purpose of this study is to improve the performance of regulated set cement, which mixed with the mineral admixtures. In this paper, setting time, compressive/flexural strength and chloride permeability of mortar according to the substitute ratio of SF, FA and BS in the range of $5\~20\%$ were conducted. Based on the test results, 5% substitute of silica fume for binder was showed good performance.

• Advances in concrete construction
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• v.8 no.3
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• pp.199-206
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• 2019

High performance sandcretes (HPS) are new concretes characterized by particles having a diameter less than 5 mm, as well as very high mechanical strength and durability. This work consists in finding solutions to make sandcretes with good physico-mechanical and durability properties for this new generation of micro-concrete. However, upgrading ordinary sandcrete into high performance sandcrete (HPS) requires a thorough study of formulation parameters (equivalent water/binder ratio, type of cement and its dosage, kind and amount of super plasticizer, and gravel/sand ratio). This research study concerns the formulation, characterization and durability, in a sulphate environment, of a high performance sandcrete (HPS), made from local materials. The obtained results show that the rheological properties of fresh concrete and mechanical strength differ with the mineralogy, density and grain size distribution of sands and silica fume used.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.785-793
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• 2003

This study is intended to analyze the effectiveness of expansive additive, shrinkage reducing agent and combination of the two to reduce the autogenous and drying shrinkage of high performance concrete using mineral admixture such as fly ash, blast furnace slag powder and silica fume. According to results, when expansive additive and shrinkage reducing agent are mixed within an appropriate mixing ratio, fluidity and air content are not influenced, and the enhancement of compressive strength is favorable at the age of 91 and 180days. At the mixing ratio of expansive additive of 5% and 10%, the autogenous and drying shrinkage is reduced by 32∼68% and 25∼49% respectively in comparison with plain concrete. And they are reduced by 18∼34% and 16∼26% respectively at the mixing ratio of shrinkage reducing agent of 0.5% and 1.0%, compared with plain concrete. The mixture of EA-SR combined with expansive additive and shrinkage reducing agent is most effective for reduction of shrinkage. Therefore, it is considered that the using method in combination with expansive additive and shrinkage reducing agent is effective to reduce the shrinkage of high performance concrete using mineral admixture such as fly ash, blast slag powder and silica fume.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.252-255
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• 1995

To reduce the size of structural members, high strength concrete has recently been utilized for structure such as ultra-high-rise buildings and prestressed concrete bridges in North America. And its compressive strength has gone up to 1300kgf/$\textrm{cm}^2$. In Japan. research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project, and this Project purposed to develop the design compressive strength of 1200kgf/$\textrm{cm}^2$. Considering these circumstance. the aim of this experimental study is to develop ultra-high-strength concrete with compressive strenght over 2300kgf/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence the manufacturing of ultra-high-strength concrete. The experimental factors selected in this study are mixing methods. curing methods. water-binder ratio, maximum size of coarse aggregate, and the replacement proportion of cement by silica fume. The results of this expermental study show that it is possible to develop the ultra-high-stength concrete with compressive strength over 2300kgf/$\textrm{cm}^2$.