• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4C
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• pp.265-273
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• 2006

This study aims at evaluation of the fire resistance performance of cementitious materials for fire protection of tunnel. For this purpose, the research procedure was divided into three parts. First, base mix proportion with different material type were determined by fire test. Second, the fire test of cementitious materials for fire resistance were performed on base mix proportions to evaluated their performance. Third, the performance of cementitious materials for fire resistance compare to the target value and existing commercial products. If the performance of developed cemetitious materials for fire resistance were satisfied the target value, this studies were stopped. But, this research return to first process if the performance of cementitious materials for fire resistance are not satisfied the target value. As a result of this study, the spalling did not happen for develop and existing commercial product. Also, developed cementitious materials for fire resistance are shown with excellent compressive strength, flexural strength, and bond strength, because it used a height density aggregate. And developed cementitious materials has sufficient resistance for fire.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.47-48
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• 2014

This study is to hydration property of low carbon type recycled cement from waste cementitious powder and cement raw materials. Waste cementitious powder possible to low carbon type recycled cement in small part of additive materials. Also, low carbon type recycled cement using waste cementitious powder is suitable for low heat type cement.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.79-86
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• 2004

The purpose of this study was the development of a recycling process to recover the hydraulic properties of hydration products which account for a large proportion of cementitious powder from concrete waste. This process was performed to recycle cementitious powder as recycle cement. Therefore, after the theoretical consideration of the properties of recycle process of recycled aggregates and cementitious powder, we investigated the hydraulic properties of cementitious powder under various temperature conditions in hardened mortar which was modeled on concrete waste. And we analyzed properties of chemical reactions of recycled cement with admixture materials such as Fly-Ash, Blast Furnace Slag As a result of the experiment, the most effective method to recover hydraulic properties of the cementitious powder from concrete waste was condition of burning at 700℃ for 120 minute. And it is shown that the fluidity of mortar was decreased rapidly when the burning temperature of recycle cement was increased. However, the compressive strength and fluidity were improved significantly when admixture materials such as Fly-Ash or Blast Furnace Slag was added.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.212-213
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• 2018

The cementitious composites have been developed to satisfy various demands of the construction market. The conductive concrete, which is a carbon-based cementitious composite, was used for the deicing or the detecting the internal crack. The cement-based battery is a technology that applies the basic concept of the alkaline battery to these conductive concretes. The cementitious composites could have a function as batteries, through a mixing of anode and cathode, which were consist of the zinc and manganese dioxide powder. The carbon-based materials, which have a significant effect on electrical properties, could be considered as the main variable in cement-based batteries. Therefore, in this study, the effects of carbon-based materials were investigated. Two types of materials, including the Carbon black and Multi-walled carbon nanotube(MWCNT), were considered as the main variables. From the experiment results, the electrical characteristics such as resistance, voltage, and current were compared according to the age.

• Journal of the Korea institute for structural maintenance and inspection
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• v.1 no.1
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• pp.107-112
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• 1997

A series of reinforced concrete beams was tested to evaluate the flexural performance of the repaired RC beams. The key parameters for this study were the size and location of the patch, and the repair materials, including polymer, polymer-cementitious and cementitious materials. The repaired specimens failed by a typical flexural mode with minor interfacial bond failure. Beams repaired with polymer, polymer-cementitious and cementitious materials recover 100%, 91%, and 97% of the flexural strength respectively, while beams with cement mortar lose approximately 30% of the strength. Compared with the pressure injection techniques the specimens repaired with patching techniques show low flexural strength, with significant interfacial bond failure. Location and size of the repaired part do not affect the recovering performance. Interfacial behavior between repair and strengthening materials is the major influencing factor for the composite structures.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.17-25
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• 2010

We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

• Structural Engineering and Mechanics
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• v.72 no.1
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• pp.19-30
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• 2019

The mechanical behavior of Fiber Reinforced Cementitious Composites (FRCC) under direct shear is studied through experiment and analytical simulation. The cementitious composite considered contains 55% replacement of cement with fly ash and 2% (volume ratio) of short discontinuous synthetic fibers (in the form of mass reinforcement, comprising PVA - Polyvinyl Alcohol fibers). This class of cementitious materials exhibits ductility under tension with the formation of multiple fine cracks and significant delay of crack stabilization (i.e., localization of cracking at a single location). One of the behavioral parameters that concern structural design is the shear strength of this new type of fiber reinforced composites. This aspect was studied in the present work with the use of Push-off tests. The shear strength is then compared to the materials' tensile and splitting strength values.

• Advances in concrete construction
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• v.3 no.1
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• pp.15-37
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• 2015

Ongoing efforts for improved fracture toughness of engineered cementitious materials address the inherent brittleness of the binding matrix at several different levels of the material's geometric scale through the addition of various types of reinforcing fibers. Crack control is required for crack widths that cover the entire range of the grain size spectrum of the material, and this dictates the requirement of hybrid mixes combining fibers of different size (nano, micro, macro). Use of Carbon Nano-Tubes (CNT) and Carbon Nano-Fibers (CNFs) as additives is meant to extend the crack-control function down to the nanoscale where cracking is believed to initiate. In this paper the implications of enhanced toughness thus attained at the material nanostructure are explored, with reference to the global smeared constitutive properties of the material, through consistent interpretation of the reported experimental evidence regarding the behavior of engineered cementitious products to direct and indirect tension.

• Advances in concrete construction
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• v.11 no.4
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• pp.323-333
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• 2021

The main objective of this study is to characterize and evaluate the hydrophobic performance of polymer-based water-repellent coatings on cementitious mortar surfaces. Different concentrations of poly(vinyl acetate) (PVAc) and poly(1,4-butylene adipate) (PBA) were prepared in the laboratory and their applicability and performance was tested experimentally by water absorption test and analysis of surface contact angles of cementitious mortar specimens. According to the results of this study, it can be stated that incorporation of nano polymer particles on the surface of cementitious mortar specimens can enhance contact angles and reduce water absorption by increasing hydrophobicity. However, a dosage limit exists for polymer materials in coating, and observed hydrophobic improvements decreases when polymer dosage reached beyond the limit. Additionally, it is observed that water absorption of polymer coated cementitious mortars is closely related with the results of surface contact angle.

• Computers and Concrete
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• v.22 no.1
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• pp.83-91
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• 2018

Various systems for simulating particulate matter are developed and used in concrete technology for producing virtual cementitious materials on the different levels of the microstructure. Basically, the systems can be classified as two distinct families, namely random sequential addition systems (RSAs) and discrete element methods (DEMs). The first type is hardly being used for this purpose outside concrete technology, but became popular among concrete technologists. Hence, it is of utmost relevance to compare the two families in their capabilities, so that the reliability of produced data can be estimated. This paper pursues to do this on the basis of earlier published material of work performed by a succession of PhD students in the group of the second author. Limited references will be given to external sources.