• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.42-47
• /
• 1995

The flow properties of xoncrete depend on form of fine aggregate, the ratio of voides of fine aggregate and cement paste So, in this study, investigated for the improvement of rheology properties on mortar and paste replaced by Zeolite $\circled1$ The slump flow have to do with correlation on yielding value of mortar respectirely. $\circled2$The increase ratio of strength Mortar and paste 10% replaced by Zeolite was presented significently but the slump flow was decteased stiffly as the increase of plastic viscosity at the ratio of replacement over 10%

• Journal of the Korea Institute of Building Construction
• /
• v.8 no.2
• /
• pp.99-106
• /
• 2008

To improve concrete tensile strength and bending strength, New plan that have more economical and simple manufacture process is groped. By an alternative plan, chemical pre-stressed concrete is presented. In this study, we analyzed the rheological properties of cement paste with the kind and replacement ratio of k-type CSA type expansive additives that is used mainly in domestic. and we suggested that the algorithm of a mixing plan in the chemical pre-stressed concrete and from this, we presented the basic report for the right mixing plan. From the results, Flow increased more or less according to use of expansive additives. This phenomenon was observed by increasing paste amount that shows as substitution for expansive additives that specific gravity is smaller than that of cement. As linear regression a result supposing paste that mix expansive additives by Bingham plastic fluid. The shear rate and shear stress expressed high interrelationship. therefore, flow analysis of quantitative was available. The plastic viscosity following to replacement ratio of expansive additives is no change almost, the yield value is decreased in proportion to the added amount of expansive additives. Through this experiment, we could evaluate rheological properties of cement paste using the expansive additives. Hereafter by an additional experiment, we must confirm stability assessment of material separation by using the aggregate with the kind and replacement ratio of expansive additives.

• Architectural research
• /
• v.13 no.1
• /
• pp.25-32
• /
• 2011

The purpose of this research is to investigate the effect of specific hydration reaction on the stiffening process of cement paste. The cement compositions are manipulated to cause specific hydration reactions (secondary gypsum and syngenite formation) responsible for false set, and the relationship between specific hydration reactions and the flow and stiffening behavior of cement paste were investigated using modified ASTM C 403 penetration resistance measurement and oscillatory shear rheology. X-ray powder diffraction (XRD) was used for the phase identification associated with premature stiffening of cement paste. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were used for verification of syngenite formation. From the results, both secondary gypsum and syngenite formation caused faster stiffening and set. The amount of syngenite produced during 1 hour hydration was approximately 1 % of total mass of the cement paste, but cement paste with syngenite formation showed significantly accelerated stiffening behavior compared to normal cement paste.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.13-14
• /
• 2022

This study investigated the effect of fly ash content on the isothermal hydration heat of cement pastes. Two different pastes with fly ash content were studied to cure at 35℃. The hydration heat flow deceleration stage of slurry was simulated and compared by Jander Equation and Ginstling-Brounshtein Equation. The results show that Jander Equation and Ginstling-Brounshtein Equation have certain defects in the modeling of the deceleration stage of the heat flow of cement fly ash paste, and the fitted curve can not describe the deceleration stage well.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.11a
• /
• pp.269-270
• /
• 2012

In this study, for purpose of having a prediction on the flowability of mortar, we use the theory of excess paste, which gives a relationship between viscosity of paste versus water-binder ratio and mortar flow versus relative excess paste volume. Pastes and Mortars with four different mix proportions incorporating mineral admixtures were prepared. As a result of experiment, it seems that high flowability of mortar can be attributed to both lower viscosity of paste and increasing the volume of excess paste.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.741-744
• /
• 2008

There are two ways to reduce cement content for a given quality level(strength, workability etc.) in concrete. First, reducing the required paste volume by varying the shape or the grading of aggregates. Secondly, holding the paste volume constant while replacing cement volume with mineral admixtures or mineral fillers. And It will also be proved that the required minimum paste volume is independent of the paste composition, provided the paste composition is in a reasonable range. In this study, therefore, we have an object to determine the required minimum paste volume for a given workability level. For this purpose, we tried the following experiments: vary the paste volume for the three different grading of aggregates and determine the minimum paste volume to achieve a certain level of workability with high-range water reducing admixture.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.29 no.2
• /
• pp.1-13
• /
• 2011

The recent spotlight on electronic touch-screen display, a rapid breakthrough in the information society is evolving. Touch panel input device such as a keyboard or mouse without the use of, the on-screen character or a specific location or object on the person's hand touches a particular feature to identify the location of a panel is to be handled. The touch screen on the touch panel is used in the Ag paste is used mostly for low-curable paste. The thermal-curing paste according to the drying process of thermal energy consumption and improve the working environment of organic solvents have problems. In this study, Ag paste used in the non-thermal curing friendly and cost-effective UV curable paste was prepared. Current commercially available thermal-curable binder, was used instead of the flow characteristics of UV-curable oligomers and monomers with functional groups to give a single conductive Ag paste with the addition of a pattern could be formed. Ag paste as a result, thermal-curing adhesive, hardness, resistance and excellent reproduction of fine patterns and was available with screen printing environmentally friendly could see its potential as a patterning technology.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2004.09a
• /
• pp.257-261
• /
• 2004

Recently, Pb free solder technologies are developed, and start using for many packaging items. But this technology contains many problems. They are very high re-flow temperature and high cost than normal solder paste. Specially, high re-flow temperature effects heavy damage to packaging and occur many crack to packaging. We developed special ACI (anisotropic conductive ink) that becomes substitution of solder paste. This technology cans adhesive lower temperature such as $120\~150^{\circ}C$. Adhesion time is very short, too. This technology is suitable for mass production.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.2
• /
• pp.85-90
• /
• 2014

Ag paste has been used in the front electrode of the Si-solar cell. It is composed by Ag powder, glass frit, binder, solvent and dispersant. The role of the binder and the solvent is to make a flow and a printing property. However, it was not enough to report the printing properties with the variation of binder in the controled viscosity. In this study, we selected 3 kinds of typical binder which were used as binder for the paste in the industry, such as Ethyl cellulose, Hydroxypropyl cellulose and Acrylic. Ag pastes using these were prepared, controled viscosity and printed on the SiNx coated Si wafer. In the 'A paste' used Acrylic binder, printed hight was highest and 'H paste' used Hydroxypropyl cellulose binder was lowest. Because 'H paste' was high viscosity due to the molecular weight, the solvent was added in the paste to control the viscosity. Therefore, the content of solid was lower in 'H paste'. The relative pattern width which is related to the spreading of paste was the best in the case of 'H paste' and 'EH paste' at $30^{\circ}C$. It is thought that the optimization of the relative pattern width is possible for a paste by the controling shear thinning phenomenon. In the case of 'A paste', though printing hight was best, the pattern width was dependant on the temperature.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.85-86
• /
• 2022

In this study, a simulation using Company A's COMSOL heat flow program was used to analyze the thermal diffusion simulation according to the depth of the high-temperature exposed cement paste. As a result of the analysis, it showed a similar relationship with the measured temperature as of 180 minutes.