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Journal articles on the topic 'Hydration process'

Author: Grafiati
Published: 4 June 2021
Last updated: 28 January 2023

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1

Tan, Hong Bo, Bao Guo Ma, Kai Ke, and Jun Xiao. "Mechanism of Preferential Adsorption of Carboxylic-Vinyl Copolymer, Hydroxy Carboxylate and Sulfonation - Polyol in Cement Hydration Process." Advanced Materials Research 194-196 (February 2011): 1035–40. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1035.

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In the ternary system of hydroxy carboxylate (HC), sulfonation-polyol (SP) and carboxylic-vinyl copolymer (PC), HC and SP preferentially adsorb on the surface of particles to shield the initial hydration. In this way, the ternary system has excellent dispersibility and holding dispersibility, and it has little effect on later hydration. By means of the chemical shrinkage, SEM and XRD analysis, the hydration mechanism of the hydroxy carboxylate (HC) and sulfonation-polyol (SP) has been discussed and the preferential adsorption model (PAM) has been established. The results show that HC delays the initial hydration of C3S and accelerates both the hydration of C3A and the formation of AFt; HC reduces the strength for 28 d with the addition of 0.2%; SP delays initial hydration of C3S and C3A; the ability of shielding hydration becomes weaker along with cement hydrating and the development of strength is normal. In the ternary system of HC, SP and PC, HC and SP with the electrostatic attraction of -SO3- and COO- and complexation of OH- preferentially adsorb on the surface of particles and active hydrating points. Then, reaction of active hydrating points was shielded and the growth of the hydration products slows. In this way, hydration of C3A and C3S are delayed, and the holding dispersibility of PC becomes better. The PC preferentially adsorbs on inert hydrating points and consumes slowly to provide dispersibility with steric hindrance. Along with hydrating going on, organic compounds are enwrapped by hydration products and the shielding ability becomes weaker and weaker. Then, the hydration becomes normal.
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2

Matysík, Michal, Tomáš Vymazal, and Iveta Plšková. "Effect of Superplasticizers on the Cement Hydration Process." Advanced Materials Research 1100 (April 2015): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.1100.3.

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The cement hydration is an exothermic reaction. The hydration heat is characterizing quantitatively the clinker hydration degree. Monitoring its time response makes it possible to determine not only the heat released during a certain time interval but also the concrete mix setting onset, the cement hydration degree (when evaluating the cement applicability after a long storage period) etc. The measurement of the hydration heat or the temperature versus time plot for a hydrating mix makes it possible to identify the effect of the different additives and admixtures on the mix hydration kinetics. This paper deals with the effect of adding two different super-plasticizers (lignin-sulphonate-based and naphthalene-sulphonate-based) on the hydration heat development progress. A set of iso-peribolic calorimeters was used to measure the hydration heat development process. The measurement proper consisted in monitoring and recording the temperature versus time plot for the specimen under test. The released heat amount was determined by calculation from the temperature gradient, the ambience specific thermal losses, the material thermal capacity and the test specimen mass.
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3

Gazdič, Dominik, Marcela Fridrichová, Karel Kalivoda, and Jana Stachová. "Study of the Kinetics of Hydration Process of Anhydrite Using External Exciters." Advanced Materials Research 838-841 (November 2013): 2342–45. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2342.

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Due to the very gradual hydration of anhydrites and their very low strengths, modification of the properties of anhydrite by a suitable external exciter was resolved within the work. The experimental work was conducted on natural anhydride, and as possible exciters for hydration, the following products were selected and tested: water-free sodium sulphate; Portland cement CEM I 42,5 R; hydrated lime CL 90 Carmeuse. The dose of the exciter was consistent, i.e. 4.5 wt%. The affect on the increased speed of the hydrating process and the quality of the technological properties was monitored. The catalytic effect was evaluated by monitoring the course of the hydration process (using XRD analysis and thermo-gravimetric analysis) and also on the basis of the achieved technological properties.
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4

Wang, Qing, Zhao Yang Ding, J. Zhang, L. G. Qiu, and Zhi Tong Sui. "Study on Slag-Based Geopolymer Hydration Process." Key Engineering Materials 477 (April 2011): 67–71. http://dx.doi.org/10.4028/www.scientific.net/kem.477.67.

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As environment-friendly or green cement, the geopolymer cementitious material has high early age strength, good volume stability and durability. In this paper, the mechanical properties of geopolymer hydrates at different hydrating ages were studied by changing the oxide content of raw material. The results showed that the chemical-combined water kept increasing as hydrating age prolonged, and reached the maximum at n(SiO2)/n(Al2O3)=3.9, n(H2O)/n(SiO2)=2.3 and n(Na2O)/n(Al2O3)=0.6. With the development of hydration, the pH value of geopolymer paste showed fluctuated: pH value kept increased at the age of 1d～3d, then decreased at the age of 3d～7d, at the age of 7d～14d the pH value increased again and at last it remained constant at the age of 14d～28d. 28d compressive strength of geopolymer paste reached the maximum as chemical-combined water content was 0.09g～0.10g and pH value was 10～11.
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5

Ma, Bao Guo, Lei Su, Shou Wei Jian, Zhi Guang Zhao, and Min Liu. "Early Stage Hydration Process of Hydroxypropyl Methyl Cellulose Ether Modified Cement Pastes." Advanced Materials Research 476-478 (February 2012): 1709–13. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1709.

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Effect of hydroxypropyl methyl cellulose ether (HPMC) on early stage process of cement pastes and its mechanism were studied by hydration heat, chemical combined water, calcium ion concentration, TG-DTG and Ca (OH) 2 content. Results show that HPMC can significantly delay hydration acceleration period of cement pastes. Hydration acceleration period of cement pastes gradually goes back, with the dosage increasing. However, changes of HPMC dosage has little effect on deceleration period and stabilization period of cement hydration. When hydration time is less than 6 hours, chemical combined water slowly increases. Chemical combined water dramatically increases when hydration time is between 6 hours and 24 hours. After 4 hours hydration, calcium ion concentration reaches maximum 26.8mm/L in blank sample. Calcium ion concentration gradually decreases when hydration time is more than 4 hours and reach minimum 9.2 mm/L after 24 hours hydration. Calcium ion concentration of cement pastes which modified with HPMC showed the same change law. When hydration time is less than 4 hours, the content of Ca (OH) 2 in cement pastes slowly enlarges along with hydration time prolonging. The content of Ca (OH) 2 significantly increases when hydration time is more than 4 hours. At the same age, the more the dosage of HPMC is, the less the chemical combined water, calcium ion concentration and Ca (OH) 2 content.
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6

Hernandez Miranda, J., S. Soto Simental, N. Guemes Vera, J. Piloni Martini, A. Quintero Lira, and J. A. Rodriguez Avila. "Whey beverage improves hydrating capacity of the soccer players." Food Research 5, no. 5 (September 10, 2021): 63–71. http://dx.doi.org/10.26656/fr.2017.5(5).070.

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The hydration process is critical in soccer players. The hydrating capacity, energy recovery, and electrolyte excretion in urine were determined by the use of a whey beverage as a hydration medium for high-performance athletes compared to the effects of purified water and a sport beverage. The study was carried out through an approved research protocol, which contemplates the determination of hydrating capacity by monitoring body weight during a period of exercise and a subsequent hydration period. Energy recovery was determined by monitoring blood glucose levels and electrolyte excretion was performed by quantifying the concentration of sodium (Na+ ), potassium (K+ ), calcium (Ca2+) and magnesium (Mg2+) in urine samples provided by the participants during the research protocol. It was concluded that the whey beverage has an appropriate capacity for hydration and energy recovery, while with regard to minerals it was observed that it effectively regulates the excretion of Na+ , Ca2+ and Mg2+ .
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7

Ivanova, Irina, Andrey Pustovgar, Aleksey Eremin, and Aleksey Adamtsevich. "Special Aspects of Hydration Process of Microfine Cement." Applied Mechanics and Materials 725-726 (January 2015): 578–83. http://dx.doi.org/10.4028/www.scientific.net/amm.725-726.578.

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The aim of the present research was to determine special features of hydration process of two commercial microfine cements compared to CEM I 42.5N cement with similar mineralogical composition. The influence of cement fineness and composition on the hydration process was investigated by isothermal calorimetry of cement pastes and quantitative X-ray powder diffraction of hydration products at 1, 3, 7, 14 and 28 days.
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8

Zhang, Ming, Zhu Ding, Feng Xing, and Peng Liu. "Resistivity Study on Early Hydration Process of Phosphoaluminate Cementitious Material." Advanced Materials Research 79-82 (August 2009): 95–98. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.95.

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An electrodeless resistivity measurement system developed recently can provide a reliable method for monitoring the hydration process of cement-based materials continuously and accurately. Phosphoaluminate cement (PAC) sets quickly and develops high early strength. In order to understand the mechanism, the hydration products and microstructure formation of PAC in early age need to be studied. In the study, early hydration process of PAC with different dosage of retarder was investigated by the electrodeless resistivity equipment. According to resistivity-time curve, resistivity of freshly mixed PAC paste decreases sharply and then rises slowly, some characteristic peaks appear at different hydration stages of PAC. Heat evolution of PAC was also measured. The hydration mechanism and structure formation were studied according to these results. Depending on the dosage of retarder, the hydration process of PAC includes four stages which are dissolution, induction, acceleration and deceleration.
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9

Perrier, Erica T., Lawrence E. Armstrong, Michel Daudon, Stavros Kavouras, Max Lafontan, Florian Lang, François Péronnet, Jodi D. Stookey, Ivan Tack, and Alexis Klein. "From State to Process: Defining Hydration." Obesity Facts 7, no. 2 (2014): 6–12. http://dx.doi.org/10.1159/000360611.

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10

Siyao, Huang, Xu Mingbiao, Xu Peng, Zhang Yu, and Wang Xinying. "Composite Hydration Process of Clay Minerals Simulating Mineral Clay Components and Influence Mechanism of Cations." Energies 15, no. 20 (October 13, 2022): 7550. http://dx.doi.org/10.3390/en15207550.

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Clay minerals are an important part of the mud shale reservoir, and their type of content has a great impact on the hydration of the formation. The hydration of clay minerals causes a decrease in drilling fluid performance, an increase in pore pressure, and a decrease in rock strength, leading to wellbore wall collapse. Therefore, it is important to study the influence of clay mineral hydration on well-wall stability. In this paper, we analyze the hydration process of clay minerals qualitatively and quantitatively by simulating the mineral clay fraction and the effect of the change in cations on their hydration and clarify the difference in the hydration of different clay minerals. The results show the following: (1) montmorillonite has the most obvious hydration and swelling effect, while the hydration of illite is mainly based on hydration and dispersion, which easily produce exfoliations and fall off in the stratum; kaolinite has poor hydration performance, while chlorite shows certain hydration but low hydration degree. (2) Cations have a certain inhibitory effect on the hydration of clay minerals, and the degree of hydration inhibition is different for different types. (3) Different clay minerals also differ in the form of state after water exposure, as montmorillonite shows swelling, while illite has no swelling, but its dispersion is stronger.
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11

Wang, Jia Chun. "Investigation of Hydration Heat of Slag in Portland Cement Environment." Advanced Materials Research 261-263 (May 2011): 431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.431.

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The hydration of slag in Portland cement is studied by considering the interaction between the hydrations of slag and Portland cement clinker. The slag hydration heat value that the different dosage of slag is in Portland cement is measured with isothermal calorimetry method as quartz sand sample contrast. The kinetic analysis was used to obtain parameters, which were employed to find out the influence of the slag content on the reaction rate constant value. The reaction stages have been analyzed and explained in accordance with kinetic models. The model predictions show that as the slag proportions in the blended cement changes, water retention in the hydration products changes only slightly if compared to that of Portland cement, The investigations have shown that the addition of silica fume of more than 30 mass% reduces the duration of the phase boundary interaction as a rate-determined process resulting in the fast diffusion rate-determining process. The results of this study have also revealed evidence of the accelerator effect of slag during the first 24 h of hydration when it still exists as chemically inert filler.
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12

Li, Hua, Jia Ping Liu, Qian Tian, and Shou Zhi Zhang. "Hydration Kinetics and Microscopic Analysis of Calcium Oxide Expansion Clinker." Applied Mechanics and Materials 477-478 (December 2013): 908–14. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.908.

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Hydrating and calcining method combined with the kinetic equation were adopted to describe the hydration kinetics process of the laboratory-calcined CaO expansion clinker, XRD and SEM were used to test and analysis its mineral compo-sition and microstructure as well. The results show that, hydration reaction process in pure water of f-CaO contained in the CaO expansion clinker meets the Avrami isothermal crystallization kinetics model, and the hydration degree increases with temperature, with the relation between reaction rate constant and temperature conforming to Arrhenius law; the CaO expansion clinker powder contains a large number of particles in which f-CaO, CaSO4, Ca4Al6O12SO4 (partly still containing calcium silicates) phases existing at the same time, by the impact of the presence of impurity phases and the difference of calcining conditions, the hydration activity of f-CaO contained in CaO expansion clinker was different from that of pure CaO and that of f-CaO wrapped in cement clinker or high-calcium fly ash.
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13

Wen, Jing, Hong Fa Yu, Xue Ying Xiao, and Jin Mei Dong. "Influence of Materials Ratio on the Hydration Process of Magnesium Oxychloride Cement." Materials Science Forum 817 (April 2015): 180–84. http://dx.doi.org/10.4028/www.scientific.net/msf.817.180.

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Magnesium oxychloride cement (MOC) has the characteristics of big heat and heat concentration in the hydration process. During the hydration process there is an adverse effect on the formation of hydration products and strength as well as volume stability. The hydration heat method was used to study the hydration process of MOC and analyze the influence of materials ratio on the hydration process in the present investigation. The results show that the hydration process could be divided into five stages, inclding initial stage, induction stage, acceleration stage, retardation stage and stable stage. It has been found that with the increasing of the molar ratio of MgO/MgCl2, the induction stage and acceleration stage extended, and heat release ratio and total heat of 3 days were reduced. With the increasing of the molar ratio of H2O/MgCl2, the induction stage is cut down, acceleration stage is in advance and heat release ratio first rising and then down, and the total heat of 3 days are reduced. It may be concluded that the influence of ratio on the hydration process of MOC is mastered, providing the bases to further improve the properties of magnesium oxychloride cement products.
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14

Ukrainczyk, Neven, Jure Zlopasa, and Eduard Koenders. "Hydration Process of Portland Cement Blended with Silica Fume." Advanced Materials Research 699 (May 2013): 578–83. http://dx.doi.org/10.4028/www.scientific.net/amr.699.578.

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The enormous carbon footprint associated with the global cement production (5-7%) asks for a radical change in the use of sustainable replacement materials in concrete. Replacement of cement by pozzolanic waste materials, being a by-product from industrial processes, has been widely recognized as the most promising route towards sustainable construction materials. This paper presents experimental study on hydration of commercial Portland cement blended with silica fume in replacement ratio of 15 mass %. Isothermal calorimetry was employed to monitor the hydration kinetics. Thermogravimetric analysis coupled by differential scanning calorimeter (TG/DSC) was used to investigate the formed hydration products at 1, 3, 7, and 28 days of hydration. Two different approaches for a dispersion of silica fume in cement paste were compared: ultrasound bath and addition of superplasticizer (polycarboxylic ether based).
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15

Helinski, Matthew, Andy Fourie, Martin Fahey, and Mostafa Ismail. "Assessment of the self-desiccation process in cemented mine backfills." Canadian Geotechnical Journal 44, no. 10 (October 2007): 1148–56. http://dx.doi.org/10.1139/t07-051.

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During the placement of fine-grained cemented mine backfill, the high placement rates and low permeability often result in undrained self-weight loading conditions, when assessed in the conventional manner. However, hydration of the cement in the backfill results in a net volume reduction—the volume of the hydrated cement is less than the combined volume of the cement and water prior to hydration. Though the volume change is small, it occurs in conjunction with the increasing stiffness of the cementing soil matrix, and the result in certain circumstances can be a significant reduction in pore-water pressure as hydration proceeds. In this paper, the implications of this phenomenon in the area of cemented mine backfill are explored. An analytical model is developed to quantify this behaviour under undrained boundary conditions. This model illustrates that the pore-water pressure change is dependent on the amount of volume change associated with the cement hydration, the incremental stiffness change of the soil, and the porosity of the material. Experimental techniques for estimating key characteristics associated with this mechanism are presented. Testing undertaken on two different cement–minefill combinations indicated that the rate of hydration and volumes of water consumed during hydration were unique for each cement–tailings combination, regardless of mix proportions.
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16

Angelescu, Nicolae, Darius Stanciu, José Barroso de Aguiar, Hakim S. Abdelgader, and Vasile Bratu. "Role of Superplasticizer Additives Upon Hydration Process of Cement Pastes." Scientific Bulletin of Valahia University - Materials and Mechanics 14, no. 11 (October 1, 2016): 23–26. http://dx.doi.org/10.1515/bsmm-2016-0004.

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Abstract The article presents a comparative analysis on the hydration of cement paste without superplasticizer and water/cement ratio of 0.35 and a cement paste with the same water/cement ratio but has in its composition 2% superplasticizer additive Glenium Sky 526. For characterizing the hydration process of cement paste, both mixtures were subjected to X-ray diffraction and thermogravimetry analysis, at 3, 7, and 28 days passed since the initiation of hydration process.
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17

Wu, Cheng Zhu, Yong He Liang, Yu Cheng Yin, Man Fei Cai, Jian Hua Nie, and Sen Cai Shen. "Characterization of Hydrolysis Process of a Silane Coupling Agent KH-570." Key Engineering Materials 768 (April 2018): 279–85. http://dx.doi.org/10.4028/www.scientific.net/kem.768.279.

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The hydrolysis process of a silane coupling agent KH-570 in deionized water, ethanol, and their mixed medium was characterized by continuous online conductivity testing, respectively. In addition, hydration products of KH-570 in different mediums were analyzed by Fourier transform infrared spectroscopy (FTIR) to correlate with its hydration process. Results indicate that the KH-570 hydrates fast and to a large degree in deionized water, but at the same time, its hydrolysis products condensate together with increasing rate during the hydration process. However, the introduction of ethanol could significantly reduce the degree of the condensation. The hydrolysis degree of KH-570 was relatively large in a mix medium of deionized water and ethanol with the mass ratio of 5:1, and condensation degree of hydrolysis products was also small. KH-570 would hydrate quickly in a hydration medium of colloidal silica, and subsequently, its hydration products would directly react with colloidal silica, which could accelerate the formation of Si-O-Si three-dimensional network structure, and thus promoting the setting of colloidal silica. The hydration of 0.9wt% KH-570 in colloidal silica could be sufficient, and correspondingly, its effect on the coagulation of colloidal silica was better.
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18

Li, Zheng Hao, Wei Guo Shen, Qing Lan, Zi Li Lu, Liang Hong Cao, and Zhi Yuan Xu. "Influence of Sucrose on Hydration Process of Portland Cement." Key Engineering Materials 599 (February 2014): 46–51. http://dx.doi.org/10.4028/www.scientific.net/kem.599.46.

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The sucrose (0.045%) is added in the cement paste, the consistency of Ca2+ and OH- reduce little, the AFt has high solubility product, thus the AFt exists as gel like product which covers the surface of the clinker particles, the sucrose acts as a retarder. When the dosage of the sucrose is 0.24%, the sucrose poisons the hydration of C2S and C3S markedly, so the consistency of Ca2+ and OH- reduce sharply, the AFt has low solubility product, the needle like AFt form a hydration product network and accelerates the setting process, C2S and C3S cannot yield enough C-S-H, the strength development is baffled. It was supposed that there are two dosage threshold values of sucrose on the hydration process, 0.01% is a retardation threshold value accelerating the formation of Aft, while 0.2% is an acceleration threshold value poisoning the hydration of C3S and C2S.
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19

Xia, Zhong Feng, Zhou Fu Wang, Xi Tang Wang, Hao Liu, and Yan Ma. "Effect of Micro-Sized Alumina Powder on the Hydration Process of Calcium Aluminate Cement." Solid State Phenomena 281 (August 2018): 249–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.249.

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Micro-sized alumina powder is widely used in low cement high-alumina refractory castables. The hydration of calcium aluminate cement can be affected by adding micro-sized alumina powder. This work addresses the hydration of a commercial cement at 25°C with 50 wt% micro-sized alumina powder added. The hydration heat was measured by isothermal micro-calorimetry. The phase composition and microstructure of the hydration products at the designated times were studied by XRD and SEM, respectively. The results showed that micro-sized alumina powder accelerated the dissolution of CAC. The induction period of the cement hydration reduced from 13h to 4.5h, and the hydration heat within 50hs was increased from 469J/g to 587J/g with the addition of micro-sized alumina powder. The morphology of the hydrates was flocculent amorphous at the beginning, and then transformed to short rods or cubic shape with micro-sized alumina powder added.
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20

Gao, Xiu Li, Wen Xu, and Hua Li. "Interventions of Retarders on the Hydration Process of CaO Expansion Clinker." Applied Mechanics and Materials 584-586 (July 2014): 1573–76. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1573.

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The volume deformation test, differential scanning calorimetry and chemical titration technique were used to experimentally research the interventions of retarders on the free autogenous volume deformation of cement paste doped with CaO expansion clinker at different ages systematically, as well as the hydration rate and hydration process of CaO expansion clinker. Two types of retarders were used as following: sodium gluconate and sodium citrate. The experimental results show that the two retarders can delay the hydration process of CaO expansion clinker, slow down its hydration rate both in pure water and cement paste. At the same time, the free autogenous volume deformation of cement paste was increased. In this sense, the use of retarders is favorable to improve the expansion efficiency of CaO expansion clinker.
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21

Fridrichova, M., D. Gazdic, K. Dvorak, J. Mokra, and K. Kulisek. "Study of hydration process of ternesite clinker." IOP Conference Series: Materials Science and Engineering 385 (July 2018): 012014. http://dx.doi.org/10.1088/1757-899x/385/1/012014.

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22

Inoue, Kaoru, Masao Iwasaki, and Naohiro Ueda. "5608123 Process for catalytic hydration of olefins." Journal of Molecular Catalysis A: Chemical 125, no. 2-3 (November 1997): 179. http://dx.doi.org/10.1016/s1381-1169(98)80108-8.

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23

Georgescu, Maria, and Alina Badanoiu. "Hydration process in 3CaO.SiO2-silica fume mixtures." Cement and Concrete Composites 19, no. 4 (January 1997): 295–300. http://dx.doi.org/10.1016/s0958-9465(97)00021-8.

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24

Mattioda, Fernanda, Luiz Mario de Matos Jorge, and Regina Maria Matos Jorge. "Wheat hydration process intensification by periodic operation." Journal of Food Engineering 246 (April 2019): 153–59. http://dx.doi.org/10.1016/j.jfoodeng.2018.11.012.

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25

Lindner, Pinhas, and John E. Kinsella. "Study of the hydration process in tehina." Food Chemistry 42, no. 3 (January 1991): 301–19. http://dx.doi.org/10.1016/0308-8146(91)90072-v.

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26

Luz, A. P., and V. C. Pandolfelli. "Halting the calcium aluminate cement hydration process." Ceramics International 37, no. 8 (December 2011): 3789–93. http://dx.doi.org/10.1016/j.ceramint.2011.06.034.

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27

Kalita, Dipsikha, Shubham Jain, Brijesh Srivastava, and Vaibhav V. Goud. "Sono-hydro priming process (ultrasound modulated hydration): Modelling hydration kinetic during paddy germination." Ultrasonics Sonochemistry 70 (January 2021): 105321. http://dx.doi.org/10.1016/j.ultsonch.2020.105321.

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28

Ammar, Marwa, and Walid Oueslati. "Crystalline Swelling Process of Mg-Exchanged Montmorillonite: Effect of External Environmental Solicitation." Advances in Civil Engineering 2018 (October 16, 2018): 1–18. http://dx.doi.org/10.1155/2018/8130932.

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This work reports characterization of the possible effects that might distress the hydration properties of Mg-exchanged low-charge montmorillonite (SWy-2) when it undergoes external environmental solicitation. This perturbation was created by an alteration of relative humidity rates (i.e., RH%) over two hydration-dehydration cycles with different sequence orientations. Structural characterization is mainly based on the X-ray diffraction (XRD) profile-modeling approach achieved by comparing the “in situ” obtained experimental 00l reflections with other ones calculated from theoretical models. This method allows assessing the evolution of the interlayer water retention mechanism and the progress of diverse hydration state’s contributions versus external strain. Obtained results prove that the hydration behavior of the studied materials is strongly dependent on the RH sequence orientation which varied over cycles. The interlayer organization of Mg-exchanged montmorillonite (i.e., SWy-2-Mg) is characterized by a heterogeneous hydration behavior, which is systematically observed at different stages of both cycles. By comparing the interlayer water process evolution of Mg-exchanged montmorillonite with the observed SWy-2-Ni sample hydration behaviors, a same hysteresis thickness characterized by obvious fluctuations of interlayer water molecule abundances is observed. Nevertheless, in the case of Hg and Ba-saturated montmorillonite, the retention water process versus the applied cycles was steadier comparing with Mg ions.
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29

Huang, Senle, Jikai Yao, Yang Yang, Chunping Gu, Jintao Liu, Deyu Kong, and Xiaodong Wen. "Calorimetric Study of High-Volume Fly Ash-Cement Paste Hydration at Different Temperatures." Crystals 12, no. 6 (June 6, 2022): 802. http://dx.doi.org/10.3390/cryst12060802.

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The study on the hydration process of cement-based materials is of significance since it determines the development of the macro-properties. The hydration process of high-volume fly ash (FA)-cement based materials is quite special and needs systematic study. In this study, the hydration heat release of cement paste with high volume FA were measured with isothermal calorimetry at different temperatures. The full-width at half-maximum (FWHM) value of the exothermic peak and the cementitious index (CMI) of FA were used comprehensively to evaluate the influence of FA on cement hydration. It was found that increasing the FA content and water-binder ratio retarded the hydration process for paste but did not show obvious effects on the hydration of cement. The CMI values show that raising the temperature intensified the retarding effect of FA on cement hydration during the induction period, but promoted the subsequent hydration process. According to the normalized heat release to cement, and the change of CMI values with temperature, new evidence was found that FA may not act as nucleation sites during the hydration process of cement. The result can be better explained by the topochemical reaction mechanism.
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30

Huang, Feng Yuan, Xiao Jie Wu, Wei Feng Ying, Yong Peng Yu, and Hong Xun Chi. "Effect of Carboxylmethyl Cellulose Sulfate (CMC-S) on the Hydration Process of Cement Paste." Advanced Materials Research 838-841 (November 2013): 123–26. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.123.

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The application of Carboxylmethyl Cellulose Sulfate (CMC-S) in cement paste was studied. The effect of CMC-S on the setting time of cement paste was investigated. Hydration heat of specimens with different cured age was measured via the Hydration Heat Tester (HHT), and hydration process was recorded via Differential Scanning Calorimeter (DSC). The results indicated that CMC-S was a kind of set-retarding and water-reducing agent; its retarding properties appeared at early age, but after three days, the hydration process of cement paste was even improved.
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31

Liu, Jun, Chao Lin, Wen Hui Sun, and Xu Ming Wang. "Study on Compatibility of Modified the Cement-Based Composite Biomass Materials by Agent." Key Engineering Materials 539 (January 2013): 215–19. http://dx.doi.org/10.4028/www.scientific.net/kem.539.215.

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Abstract. For the slow process of hydration and complex process of hydration of cement-based composite biomass materials, the paper study the compatibility of straw cement mixed system was evaluated in process of hydration. By testing temperature changes in process of hydration of cement-based composite biomass materials and analyzing the maximum value of hydration temperature, the maximum temperature difference and compatibility coefficient of modified the cement-based composite biomass materials by agent, taken before or after that. It was evaluated that compatibility performance of modified the cement-based composite biomass materials by agent. The results show that the characteristic changes of early hydration heat was reflected with a visual aid by some indexes that are the maximum value of hydration temperature, the maximum temperature difference, and so on. And the early hydration behavior was more comprehensive objective reflected by compatibility coefficient in cement-based composite biomass materials. At the same time, the modified effect of sodium silicate was superior to the polyvinyl acetate (PVAc) in the early hydration of the cement-based composite biomass materials.
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32

Zhao, Haitao, Yi Wan, Jun Xie, Kaidi Jiang, Donghui Huang, Xiaodong Chen, Shihai Li, Ruiming Jia, and Gaoyang Sun. "Effects of Nano-SiO2 and SAP on Hydration Process of Early-Age Cement Paste Using LF-NMR." Advances in Materials Science and Engineering 2020 (March 23, 2020): 1–9. http://dx.doi.org/10.1155/2020/6089482.

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The effects of nano-SiO2 and superabsorbent polymer on the hydration process of early-age cement paste are investigated through the physically bound water evolution test by means of the low-field nuclear magnetic resonance technology. The test results show that the hydration process can be characterized by four-stage patterns based on the zero points of the second-order differential hydration curve, i.e., the initial, accelerated, decelerated, and steady periods. The beginning time of each stage is postponed and the hydration duration is prolonged with an increasing water to cement ratio. The beginning time of each stage and the hydration duration are shortened with an increasing content of nano-SiO2. And the beginning time of each stage and the hydration duration are prolonged with an increasing content of superabsorbent polymer. Based on the test data and the Avrami–Erofeev model, a modified hydration model taking the influence of nano-SiO2 and SAP into account is proposed, and the predicted results are consistent with the test results.
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Xing, Zhibo, Limei Bai, Yuxin Ma, Dong Wang, and Meng Li. "Mechanism of Magnesium Oxide Hydration Based on the Multi-Rate Model." Materials 11, no. 10 (September 27, 2018): 1835. http://dx.doi.org/10.3390/ma11101835.

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The hydration of different active MgO under an unforced and ultrasonic condition was conducted in this paper to investigate the chemical kinetics model of the apparent reaction and discuss the mechanism combined with the product morphology. The dynamics fitting result shows that both the first-order and multi-rate model describe the hydration process under ultrasound well, while only the multi-rate model was right for the hydration process under an unforced condition. It indicated that the rate order of hydration was different in the hydration process under an unforced condition. The XRD and SEM show that the MgO hydration was a process of dissolution and crystallization. Part of the magnesium ions produced by dissolution of MgO did not diffuse into the solution in time, and adhered to the magnesium oxide surface and grew in situ instead. As a result, the difference in the hydration rate of the remaining MgO particles becomes wider and not in the same order (order of magnitude). The ultrasonic cavitation could prevent the in-situ growth of Mg(OH)2 crystal nuclei on the surface of MgO. It not only greatly improved the hydration rate of MgO and produced monodisperse Mg(OH)2 particles, but also made the first-order kinetics model fit the hydration process of MgO well.
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34

Aliyev, A. M., A. R. Safarov, I. V. Balayev, A. M. Guseynova, R. Y. Agayeva, and F. G. Bayramov. "CONTROL OF THE DIRECT HYDRATION PROCESS OF PROPYLENE IN ACCORDANCE WITH ITS DYNAMICS." Azerbaijan Chemical Journal, no. 3 (October 10, 2019): 15–19. http://dx.doi.org/10.32737/0005-2531-2019-3-15-19.

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35

Iliushchenko, Valeriia, Lukáš Kalina, Martin Sedlačík, Vladislav Cába, Jiří Másilko, and Radoslav Novotný. "Effect of Alkali Salts on the Hydration Process of Belite Clinker." Materials 15, no. 10 (May 10, 2022): 3424. http://dx.doi.org/10.3390/ma15103424.

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Belite-rich cement is a low carbon footprint binder. However, its use is accompanied by a low initial rate of hydration. This can be partially eliminated by grinding to a high specific surface or through the addition of admixtures (mineralizators or activators). The influence of alkaline activators CaSO4, Na2SO4 and Na2CO3 (in the amount of 5 wt.% related to the clinker weight) on the hydration course, as well as the quantity of hydration products in belite-rich cements, were investigated in this paper. Belite-rich clinker was laboratory-synthetized and ground together with activators to prepare various belite-rich cements. Next, the hydration kinetics and the hydrated phase assemblage were investigated using isothermal calorimetry, X-ray powder diffraction and thermogravimetric and differential thermal analyses. The use of selected admixtures allowed us to obtain belite-rich cements with higher hydraulic activity in the initial period.
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36

Liu, Shuhua, Hongling Wang, and Jianpeng Wei. "The Role of Various Powders during the Hydration Process of Cement-Based Materials." Advances in Materials Science and Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/8394834.

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The role of various powders including glass powder (GP), limestone powder (LP), and steel slag powder (SSP) during the hydration process of cement-based materials was investigated by using X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and strength tests. GP has adverse impact on early strength, but the pozzolanic reaction at later stage enhances the strength development greatly. LP can significantly improve early strength. SSP has a good contribution to the early and later strength of the paste when its content is less than 15%. GP has little effect on the kind of hydration products but relatively large effects on the quantity. Calcium hydroxide (CH) content of GP paste decreases over curing age gradually, which is different from pure cement paste because its pozzolanic activity consumes more CH than that generated from the cement hydration. SSP and LP mainly play a role of filling effect at early stage. Nucleating effect of LP also promotes the early hydration of cement. The hydration of LP occurs at later stage and forms the calcium carboaluminate hydrates. The hydration of SSP is relatively slow, which generates CH at later stage and is effective in the strength development.
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37

Ma, Bao Guo, Jun Xiao, and Hong Bo Tan. "Citric Acid on the Hydration Mechanism of Cement." Advanced Materials Research 413 (December 2011): 174–79. http://dx.doi.org/10.4028/www.scientific.net/amr.413.174.

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This article reports on the study to evaluate the hydration process of cement by the addition of citric acid. Through the test of citric acid of cement paste, hydration heat performance, resistivity, chemical shrinkage, and combined with XRD, SEM, DSC-TG discusses the influence of citric acid on cement hydration process. The results thus obtained were compared to the hydration process of cement with the blank sample and vary of dosage of citric acid. The results show that: The early hydration about 1~2 h resistivity increases, dissolve balance stage was extended; The chemical shrinkage increased significantly, and increases with dosage; With the increase in citric acid dosage, AFt diffraction peaks increases, while the CH peak decreases, indicating that the citric acid accelerated the initial hydration of C3A, while inhibiting C3S hydration and promoting AFt generation. Key words: citric acid, mechanism ,hydration heat, resistivity
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38

Zhou, Sheng Bo, Ai Qin Shen, and Geng Fei Li. "Interaction between Slag and Clinker during Cement Hydration Process." Advanced Materials Research 857 (December 2013): 70–74. http://dx.doi.org/10.4028/www.scientific.net/amr.857.70.

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In order to investigate the activity of different original slags and the coupled relation between the slag and the clinker, the simplified slag cement system was designed in the experiment, in which clinker was replaced by lime.The reactional degree of slag in cement was determined through using chemical combined water content method, and the hydration processs were determined through using DSC-TGA. The results showed that for the different original slags, the destruction and rebuilding process of their microstructure were important to distinguish the activity of slags. And the process of slag hydration mainly experienced two stages, including microstructure destruction at early ages and microstucture rebuilding at later ages. And the variation of Calcium hydroxide content in cement indicated the interaction between the slag and clinker, and slag may improve the clinker hydration velocity.
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Tikkanen, Johanna, Andrzej Cwirzen, and Vesa Penttala. "Effects of mineral powders on hydration process and hydration products in normal strength concrete." Construction and Building Materials 72 (December 2014): 7–14. http://dx.doi.org/10.1016/j.conbuildmat.2014.08.066.

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40

Xu, Dong Yu, Lei Qin, Shi Feng Huang, and Xin Cheng. "An Exploration of 1-3 Cement/Epoxy Resin Based Piezoelectric Composite in Cement Hydration Reaction Process Monitoring." Advanced Materials Research 306-307 (August 2011): 839–43. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.839.

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1-3 type cement/epoxy resin based piezoelectric composite was designed and fabricated aiming at providing a new method for cement hydration monitoring. Combining with piezoelectric impedance technology, the cement hydration reaction process was monitored by using the composite. The research results show that in the initial cement hydration period, the resistance-frequency curves of the sensor drift toward low frequency direction, while the anti-resonance resistance value decreases gradually. With increasing cement hydration time, the resistance-frequency curves of the sensor drift toward high frequency direction and the anti-resonance resistance value shows fluctuation changes. The cement hydration reaction process can be divided into different periods according to changes of anti-resonance frequency and anti-resonance resistance value of the sensor.
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41

Al-Mattarneh, Hashem, Abdullah Alwadie, Ahmad Malkawi, and Muhd Fadhil Nuruddin. "A Novel Method for Monitoring Hydration Process of Cement Paste Material." Applied Mechanics and Materials 567 (June 2014): 333–38. http://dx.doi.org/10.4028/www.scientific.net/amm.567.333.

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A new measurement system is developed to monitor the early hydration of cementitious materials based on measured dielectric properties of the material in low electromagnetic frequency range. The objectives of this paper were to evaluate the changes in the electromagnetic properties for samples with different fly ash content and to establish the reliability of the measurement technique by comparing with results obtained by traditional method such as thermal method that is either time consuming or impractical. The method adopted in the present experimental work is a parallel plate electrode system (PPES). The suggested monitoring device for concrete hydration and strength development is based on the relationship between the electromagnetic properties such as dielectric constant, loss factor and the strength development during hydration process and curing time. In this research the electromagnetic properties of concrete is found to be dependent on the hydration and strength of concrete. Therefore the development of microstructure and concrete compressive strength can be determined by monitoring its electromagnetic properties in the frequency range of 1 to 100 kHz.
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42

Ahn, Ji Whan, Jung Ah Kim, Kwang Suk You, Hwan Kim, Hee Chan Cho, and Im Chan Lee. "The Effect of Initial Hydration Temperature on the Characteristics of Calcium Hydroxide and Aragonite Precipitated Calcium Carbonate." Solid State Phenomena 124-126 (June 2007): 815–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.815.

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Precipitated Calcium Carbonate (PCC) is obtained through three processes; that of calcination, hydration, and carbonation. Thus, changes in each process condition determine the particle size or morphology of the mediums (calcium oxide and calcium hydroxide) as well as the product (PCC). To date, studies concerning precipitated calcium carbonate have mainly focused on the carbonation process, aimed at the manufacturing of PCC. Thus far, few studies on calcination or hydration have been conducted. Calcium hydroxide is regarded as the most important factor during the carbonation process. It is obtained through a hydration process. Therefore, in order to create the valuable PCC studies that center on the hydration process should be carried out. The present study seeks to investigate the effect of the hydration condition, particularly the temperature, on the synthesis characteristics of calcium hydroxide and aragonite PCC. The results show that the particle size of calcium hydroxide changes with variations in the initial hydration temperature. In particular, a higher initial temperature resulted in a larger particle size of the calcium hydroxide used in the synthesis. The particle size and yield of aragonite also increased when calcium hydroxide created at high temperatures was used. However, the water/solid ratio or total amount at the hydration time had no effect on the manufacturing process of aragonite.
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43

Choi, M. H. M., Z. S. Tang, R. Vasquez Padilla, Y. Y. Lim, and A. Mostafa. "A study on monitoring the hydration process of glasscrete using electromechanical impedance technique." IOP Conference Series: Materials Science and Engineering 1229, no. 1 (February 1, 2022): 012005. http://dx.doi.org/10.1088/1757-899x/1229/1/012005.

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Abstract Glass has been suggested as a viable material to replace aggregates in concrete to maintain sustainable development for the future. However, a concern is raised about the cementitious reaction with glass that could cause concrete spalling and loss of strength. Therefore, monitoring the concrete hydration process and the structural health throughout its service life is essential. In this study, the hydration process of lab-scale glasscrete prisms is monitored using the electromechanical impedance (EMI) technique. This technique employs one piezoelectric-based transducer that encases a material called Lead Zirconate Titanate (PZT) to operate as an actuator and senor. The experimental result shows that the embedded transducer is an effective means to monitor the glasscrete hydration process. The acquired admittance signature was able to capture the strength development during the glasscrete hydration period via interpreting the PZT and structural resonance peaks
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44

Park, Ki-Bong, Yi-Sheng Wang, and Xiao-Yong Wang. "Property Analysis of Slag Composite Concrete Using a Kinetic–Thermodynamic Hydration Model." Applied Sciences 11, no. 16 (August 4, 2021): 7191. http://dx.doi.org/10.3390/app11167191.

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Slag is increasingly unitized for the production of sustainable concrete. This paper presents a procedure with which to analyze the property development of slag composite concrete. Experimental studies of the hydration heat and compressive strength development and simulation studies using a kinetic hydration model and a thermodynamic model were performed. First, we performed an experimental study of the isothermal hydration heat of cement–slag blends. Based on the results of the experimental study on cumulative hydration heat, the reaction degree of slag was determined. We found that the reaction degree of slag decreased as the slag content increased. Second, the reaction degree of slag and cement were used as the input parameters for the Gibbs energy minimization (GEM) thermodynamic equilibrium model. Moreover, the phase assemblage of hydrating cement–slag was determined. The trends of calcium silicate hydrate (CSH) are similar to those of strength. Based on the CSH content, the strength of hardening cement–slag blends was determined. In addition, the calcium hydroxide (CH) content resulting from the thermodynamic model shows good agreement with the experimental results. In summary, the integrated kinetic–thermodynamic model is useful for analyzing the properties of cement–slag blends.
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45

Qin, Lei, Qian Qian Zhong, Shi Feng Huang, and Xin Cheng. "Ultrasonic Monitoring of Hydration Using Embedded Piezoelectric Transducers." Advanced Materials Research 177 (December 2010): 510–13. http://dx.doi.org/10.4028/www.scientific.net/amr.177.510.

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This study utilized embedded piezoelectric transducers for monitoring of cement hydration process. Longitudinal ultrasonic transducer which was suitable for being embedded in cement paste was prepared by cutting PZT rods and coating epoxy layer. The transducers were used to generate and receive ultrasonic waves to continuously observe the hydration of cement paste. The characteristics of wave parameters such as wave velocity, amplitude and frequency were used to interpret the hydration process of cement. Relationship between the character values of the wave and the process of hydration could be established. Therefore, it is feasible to observe the hydration progress using this technology. The coupling problem existed in traditional ultrasonic monitoring of hydration can be solved and the whole life monitoring of cement materials can be also achieved through this method.
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46

Qi, Hong, Wei Qi, and Guo Dong Sheng. "Research on the Compatibility of Cement-Based Biomass Materials Modified by Early-Strength Agents." Applied Mechanics and Materials 775 (July 2015): 287–91. http://dx.doi.org/10.4028/www.scientific.net/amm.775.287.

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Aim at the slow and complicated hydration process of straw-cement mixed system and the retarding coagulation of cement-based biomass material in C3S reaction. To investigate the improving effect of early-strength agents on the hydration process of straw-cement mixed system by adding CaCl2, FeCl3 and Al2(SO4)3 which could increase the release of hydration heat, accelerate the hydration of cement and weaken the retarding effect of dissolved substances from straw. By testing the variation of temperatures in hydration process to analyze the highest hydration temperature (Tmax), the time of reaching the highest hydration temperature (t), the maximum temperature difference (△T) and the compatibility coefficients (CA) of cement-based biomass materials with modified agents and with no modified agents, and evaluate the compatibility of straw-cement mixed system. Experimental results show that Tmax, t and △T these indexes can intuitively reflect the changing characteristics of early hydration heat of cement-based biomass materials, while CA could reflect the early hydration behavior comprehensively and objectively. Meanwhile, when the dosage of early-strength agents is between 3%~8%, the growth of CA shows as follows: CaCl2 is the best, and FeCl3 is better than Al2(SO4)3.
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47

Andraos, John, and A. Jerry Kresge. "Correlation of rates of uncatalyzed and hydroxide-ion catalyzed ketene hydration. A mechanistic application and solvent isotope effects on the uncatalyzed reaction." Canadian Journal of Chemistry 78, no. 4 (April 1, 2000): 508–15. http://dx.doi.org/10.1139/v00-032.

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Rates of hydration of a number of ketenes were measured in neutral and basic solution using flash photolytic techniques, and rate constants for their uncatalyzed, kuc, and hydroxide-ion catalyzed, kHO, reactions were determined. These results, plus additional data from the literature, were found to provide the remarkably good correlation log kuc = -3.21 + 1.14 log kHO, which spans 10 orders of magnitude in reactivity and includes 31 ketenes. This good correlation implies that uncatalyzed and hydroxide-ion catalyzed ketene hydraton occur by similar reaction mechanisms, which for the hydroxide-ion catalyzed process is known to involve nucleophilic attack on the carbonyl carbon atom of the ketene. Rate constants for phenylhydroxyketene, on the other hand, do not fit this correlation, which suggests that the mechanistic assignment upon which these rate constants are based may not be correct. Solvent isotope effects on these uncatalyzed ketene hydrations are weak; most are less than kH/kD = 2. It is argued that these isotope effects are largely, if not entirely, secondary in nature and that they are consistent with both a reaction mechanism in which nucleophlic attack of a single water molecule on the ketene carbonyl carbon atom produces a zwitterionic intermediate and also a mechanism that avoids this intermediate by passing through a cyclic transition state involving several water molecules.Key words: ketene hydration, rate correlation, nucleophilic attack, solvent isotope effects, phenylhydroxyketene.
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48

Zhao, Haitao, Gaoyang Sun, Lu Yu, Kaidi Jiang, Xiaodong Chen, Ruiming Jia, Yi Wan, and Shihai Li. "Hydration of Early Age Cement Paste with Nano-CaCO3 and SAP by LF-NMR Spectroscopy: Mechanism and Prediction." Modelling and Simulation in Engineering 2019 (August 14, 2019): 1–10. http://dx.doi.org/10.1155/2019/8384051.

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In this paper, by testing the evolution of the physically bound water using the low-field nuclear magnetic resonance (LF-NMR) technology, the hydration process of cement paste with nano-CaCO3 (NC) and superabsorbent polymer (SAP) at early age is investigated. Results indicate that the hydration process can be divided into four periods according to the zero points of the second-order differential hydration curve: initial period, acceleration period, deceleration period, and steady period. Firstly, with the increase in the water to cement ratio, the starting time of the hydration period is delayed, and the duration becomes longer. Secondly, the addition of NC leads to the speedy arrival of each period and shortens the duration of each period in the hydration process, and the optimal NC content is 1.5%. Thirdly, with the increase in SAP content, the starting time of the hydration period is delayed and the duration becomes longer. Finally, based on the experimental results and the existing hydration model, the modified hydration model considering the content of NC and SAP is proposed.
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49

Wang, Feng, Pingan Chen, Xiangcheng Li, and Boquan Zhu. "Effect of Colloidal Silica on the Hydration Behavior of Calcium Aluminate Cement." Materials 11, no. 10 (September 28, 2018): 1849. http://dx.doi.org/10.3390/ma11101849.

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The effect of colloidal silica (CS) on the hydrate phases and microstructure evolution of calcium aluminate cement (CAC) was investigated. Samples hydrated with CS were obtained and characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared spectroscopy (FT-IR), hydration heat measurement and Nuclear Magnetic Resonance (NMR). The results revealed that SiO2 nanoparticles may affect the hydrates crystallization process. There was a compact structure in the CAC paste with CS, while petal-shaped hydrates with a porous structure were formed in the pure CAC paste. The maximum value of electrical conductivity for CAC paste with CS suggested that the early stage of hydration for CAC was accelerated. However, the hydration heat curves revealed that the late stage of the CAC hydration process was inhibited, and the hydration degree was reduced, this result was in accordance with Thermogravimetry-Differential scanning calorimetry(TG-DSC) curves. The fitting results of hydration heat curves further showed that the hydration degree at NG (nucleation and crystal growth) process stage was promoted, while it was limited at the phase boundaries stage, and the diffusion stage in the hydration reaction was brought forward due to the addition of CS. According to these results and analyses, the differences in the hydration process for CAC with and without CS can be attributed to the distribution and nucleation effect of SiO2 nanoparticles.
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50

Yao, Yao, and Yue Zhang. "Interior-collapsing mechanism by hydrothermal process of the MgAl2O4/MgO porous ceramic." Journal of Advanced Ceramics 11, no. 5 (April 20, 2022): 814–24. http://dx.doi.org/10.1007/s40145-022-0576-4.

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AbstractCeramic core is a critical component in the super-alloy turbine blade casting. In our previous work, a novel multi-phase MgAl2O4/MgO porous ceramic was prepared for this purpose. The most important property was that it crumbled completely after hydrothermal treatment in just pure water, due to the hydration of MgO. In this work, the hydration process of the MgO embedded in the inert matrix was investigated in detail. The collapse behaved as an interior destruction without any bulk expansion of the sample. The hydration percentage was the only factor related to the water-collapsibility. The morphology of hydration product indicated that the reaction advanced in particular direction. Based on the finite element analysis for the expansion effect on the porous structure, the interior-collapsing mechanism was proposed. During the hydration process, the MgO grains exerted pressure to the surrounding matrix and induced the collapse in the adjacent structure. This process took place throughout the matrix. Finally, the sample crumbled completely to the powders. No bulk dilatation was detected before the powdering, indicating that the collapse process would not exert pressure outward. Thus the alloy blade would not be damaged during the removal of the ceramic core. It was also predicted that the decrease in the MgO grain size was beneficial to the water-collapsibility.
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