• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.128-131
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• 2004

This paper is to investigate the mock up test results of mass concrete for transfer girder using setting time difference with super retarding agent(SRA) to reduce hydration heat. According to test results, the temperature history of plain concrete without placing lift had a steep rising curvature, and plain concrete had a big temperature difference between surface and middle section of mass concrete, which may result in occurrence of temperature crack. However, considering placing method B, because setting time of middle section concrete was retarded with an increase in SRA contents, higher hydration heat temperature was observed at surface section concrete compared with that at middle section concrete at early age, which can lower the possibility of hydration heat crack. In case of placing method C, although peak temperature of hydration heat was much lower, at early age, high crack occurrence possibility of the hydration heat attributable to the big temperature difference between middle section and bottom section of concrete was expected at bottom section concrete. Therefore, the structure above the ground like transfer girder is not applicable to consider the placing method C.

• Journal of Adhesion and Interface
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• v.8 no.3
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• pp.9-15
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• 2007

The interfacial evaluation of surface modified Jute fiber/polypropylene (PP) composites before and after hydration was investigated using micromechanical test and dynamic contact angle measurement. The IFSS of alkaline and silane-treated Jute fiber/PP composites increased, whereas after hydration, the IFSS of the untreated, alkaline- and silane-treated Jute fibers/PP composites decreased due to swelled fibrils by water infiltration. The interfacial adhesion of silane treated fiber/PP composites was higher than alkaline-treated or the untreated cases. The surface energies of Jute fiber treated under various conditions were obtained using dynamic contact angle measurement. Especially after hydration, the thermodynamic work of adhesion was calculated by considering water interlayer, which indicated the stability of IFSS between silane treated Jute fiber and PP matrix showing better than others.

• Journal of the Korean Ceramic Society
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• v.17 no.4
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• pp.208-212
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• 1980

In order to clarify the mechanism of the hydration of supersulphated slag cement, the experiments of suspension hydration were performed in the mixtures of slag+CaSO4+water or NaOH solutions with a liquid/solid ratio of 10. The liquid and solid phase of the suspension was chemically analysed and discussed. In the slag-$CaSO_4$--NaOH system, $Al_2O_3$ was dissolved under high pH condition, and the ettringite was formed by a reaction of $CaSO_4$ and $Al_2O_3$ released in the solution. As hydration progressed, ettringite coated the surface of unhydrated slag grains and inhibited the hydration reaction of slag. $CaSO_4$ was not only an activator for slag hydration, but a reactant in the hydration.

• Progress in Superconductivity
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• v.3 no.2
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• pp.188-192
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• 2002

To introduce flux pinning center in HTS-BSCCO system, nano-size MgO particles were uniformly distributed within the Bi-2223 grain by partial hydration of MgO. The existing method MgO doped Bi-2223 used nato-size MgO powders, which resulted in agglomeration during mixing or grain growth during heat-treatment due to the high surface energy of the fine particles. By hydration of the MgO surface, the agglomeration of the MgO powders was avoided and the size of remaining MgO core was controlled by changing hydration medium and time. The thin film obtained by spin coating of (Bi_$1.8/Pb_{0.4}$)$Sr_2$$_{Ca}$$2.2/Cu_3$ $O_{y}$ nitrate solution mixed with hydrated MgO showed the even distribution of nano-size MgO particles in the Bi-2212 grains.s.s.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.110-111
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• 2021

The eggshell is a type of bio-waste which is considered hazardous to the environment. In this research, the waste eggshell is utilized as a potential filler in cementitious material. This study has measured by zeta potential to analyze the interaction between the surface of the filler and the calcium ion in the solution. Meanwhile, the effect of eggshell powder on cement hydration process has been determined by isothermal calorimeter. The results show that the surface of eggshell powder have a strong adsorption of Ca2+, and addition of the eggshell powder provides a heterogeneous nucleation site for cement, which promotes the growth of hydration products.

• Smart Structures and Systems
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• v.12 no.1
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• pp.41-54
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• 2013

Concrete is known as a heterogeneous product which is composed of complex chemical composition and reaction. The development of concrete thermal effect during early age is critical on its future structural health and long term durability. When cement is mixed with water, the exothermic chemical reaction generates hydration heat, which raises the temperature within the concrete. Consequently, cracking may occur if the concrete temperature rises too high or if there is a large temperature difference between the interior and the exterior of concrete structures during early age hydration. This paper describes the contribution of novel Fabry-Perot (FP) fiber optic temperature sensors to investigate the thermal effects of concrete hydration process. Concrete specimens were manufactured under various water-to-cement (w/c) ratios from 0.40 to 0.60. During the first 24 hours of concreting, two FP fiber optic temperature sensors were inserted into concrete specimens with the protection of copper tubing to monitor the surface and core temperature change. The experimental results revealed effects of w/c ratios on surface and core temperature developments during early age hydration, as well as demonstrating that FP fiber optic sensors are capable of capturing temperature variation in the concrete with reliable performance. Temperature profiles are used for calculating the apparent activation energy ($E_a$) and the heat of hydration (H(t)) of concrete, which can help us to better understand cement hydration.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.211-218
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• 1990

CA2-based clinker with highly activated surface and hydraulic properties was synthesized at a comparatively lowr temperature than that of conventional synthesis by "hydration-burning method". This consists of calcining the mixture of CaCO3 and Al2O3 to obtain a primary clinker, hydrating the primary clinker and reburning the hydrates to obtain final clinker. Burning of primary clinker above 1200℃ was necessary to eliminate free CaO in it and to obtain it's solid hydrate. However, rising the burning temperature above 1300℃ is ineffective due to the decrease in hydraulic properties of the primary clinker with the temperature. Hydration of primary clinker at the elevated temperature(>35℃) was required to obtain the hydrate with more porous structure and final clinker with more active surface. CA2 was formed and increased with temperature at above 1150℃, finally became a primary phase of the final clinker. However, burning at the temperature above 1300℃ resulted in reverse effect on the hydraulic properties of the final clinker due to rapid decrease in it's surface area with the temperature.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.85-90
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• 2009

Although most of existing hydration heat control methods show a certain degree of hydration heat control, generally, there are many problems as mentioned above. Therefore, our laboratory previously developed a hydration heat control method using an exposed heat pipe, which solves most of these problems and simultaneously displays excellent hydration heat control. Unfortunately, even this method had some problems such as the processing, transport, and assembly of heat pipes, and the surface treatment of a cut plane after pouring, and hardening concrete. Therefore, in this study, a hydration heat control method using an embedded pipe has been developed with the expectation that this method solves those problems in hydration heat control using an exposed heat pipe. As a result of the experiment, the peak temperature of ECHP and ICHP specimen about $4.5{\sim}6.5^{\circ}C$ than the OPC specimen and the probability of thermal cracked generated in ECHP and ICHP specimen decreased up to $13{\sim}20%$. Finally, it was confirmed in this study that the hydration heat control method using an embedded heat pipe is significantly more superior and cost effective than the existing method of an exposed one.

• Analytical Science and Technology
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• v.26 no.6
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• pp.395-400
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• 2013

The hydration and antimicrobial peptide effects on the lipid alignment on the surface of a thin glass plate were investigated by using the solid-state nuclear magnetic resonance spectroscopy. Pure 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphotidylcholine (POPC) lipid molecules were well aligned on the surface of a thin glass plate without direct hydration by placing the sample for a few days in the desiccator containing a saturated sodium phosphate dibasic solution, which provided 95% relative humidity. But there was a big difference between two lipid phases, the one of which was hydrated by placing the sample for a few days in the desiccator with 95% relative humidity without direct hydration and the other was directly hydrated by dropping water and then placed for a few days in the same desiccator. The surface mobility of POPC molecules in a lipid bilayer phase was much activated by water. While the time for the POPC to align on the glass plate surface was short, the time for the PG-1/POPC mixture to reach the its equilibrium state was long.

• Computers and Concrete
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• v.15 no.6
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• pp.989-999
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• 2015

An advanced continuum-based multi-physical single particle model was recently introduce for the hydration of tricalcium silicate ($C_3S$). In this model, the dissolution and the precipitation events are modeled as two different yet simultaneous chemical reactions. Product precipitation involves a nucleation and growth mechanism wherein nucleation is assumed to happen only at the surface of the unreacted core and product growth is characterized via a two-step densification mechanism having rapid growth of a low density initial product followed by slow densification. Although this modeling strategy has been shown to nicely mimic all stages of $C_3S$ hydration - dissolution, dormancy (induction), the onset of rapid hydration, the transition to slow hydration and prolonged reaction - the major criticism is that many adjustable parameters are required. If formulated correctly, however, the model parameters are shown here to be statistically independent and significant.