Journal of the Chinese Ceramic Society 

About: Journal of the Chinese Ceramic Society is an academic journal. The journal publishes majorly in the area(s): Cement & Microstructure. It has an ISSN identifier of 0454-5648. Over the lifetime, 1544 publications have been published receiving 4231 citations.

Kinetics model for the hydration mechanism of cementitious materials

Abstract: A kinetic model is introduced for the hydration of cementitious materials. Based on the model and the measured hydration emission heat under isothermal condition, integral and differential equations are derived to simulate the three basic processes in the hydration of cementitious materials: nucleation and crystal growth (NG), interactions at phase boundaries (I) and diffusion (D). The kinetic factors such as reaction rate constant K, reaction exponent n and apparent activation energy Ea are determined. The relationship between the reaction rate and the degree of reaction is discussed at different stages of reaction. The derived reaction rate curves compared well with the hydration rate of cementitious materials obtained from the measured hydration emission heat. An understanding to the complex hydration mechanism of cementitious materials is provided by studying the connection among the three processes. There are two different approaches for the hydration reaction of cementitious materials: NG–I–D and NG–D. NG dominates in the early stage of hydration. I or D becomes the dominating factor gradually as the hydration degree increases.

Synthesis and structure characterization of geopolymeric material based on metakaolinite and phosphoric acid

Abstract: A geopolymer material based on dehydrolyed aluminosilicate and phosphoric acid was synthesized from metakaolinite condensed with low-polymeric \~(3n-)_n tetrahedral units in phosphoric acid aqueous solution at room temperature.The product of the geopolymerization has a polymeric Si-O-Al-O-P three-dimensional structure.The material structure and geopolymerization mechanism of the products were investigated using X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectroscopy,and()~(29)Si and()~(27)Al magic angle spinning nuclear magnetic resonance(NMR).The results show that there are three chemical environments for Al~(3+) in the geopolymer.The NMR chemical shift of()~(29)Si in the product is presented only at110,which demonstrates that the linking amongtetrahedral units keeps the layer structure in the geopolymers.In the infrared spectrum of the geopolymer,the resonance absorbance peak of 800 cm~(-1) of the Al-O layer of metakaolinite disappeared.The XRD pattern of the obtained polymers is essentially amorphous.A model of the geopolymerization mechanism was proposed to explain the experimental results.

Interfacial transition zone between aggregate and paste in cementitious composites (ii): mechanism of formation and degradation of interfacial transition zone microstructure,and its influence factors

Abstract: The microstructure models of interfacial transition zone( ITZ) were represented. The mechanism of formation and degradation of ITZ's microstructure was described by three stages. They involve: (1) the fresh stage of concrete and the early period of hy-dration, (2) the hardened period and (3) the service period of materials. At the first stage, the mechanism is possibly due to a wall effect, flocculation of binder, microbleeding effect, transportation, precipitation and nucleation of ion, one-sided growth of hydrated products and syneresis. At the second stage, chemical shrinkage, self-desiccation shrinkage, drying shrinkage, the difference in expansion coefficient between aggregate and paste, hydration of paste and re-crystallization of hydrated products can be contributed to the mechanism. At the last stage, the mechanism is attributed to the load, aggressive agent, freeze-thaw, alkali-aggregate reaction and continuous hydration of paste. In this review, the conventional characteristic methods of ITZ's microstructure were briefly described. The new characteristic method and two alternative approaches were shown. In addition, the influence of physical and chemical characteristics of raw materials, mixture design and processing on the microstructure of ITZ were reviewed.

Effect of heat treatment on structure, morphology and surface properties of palygorskite

Abstract: The dehydration, structural and morphological properties of palygorskite during heat treatment were studied by thermogra-vimetric and differential thermal analysis, X-ray diffraction and high resolution transmission electron microscopy The results indicate that water is absorbed in the channel and outside surface of the palygorskite samples, causing dehydration at 65 ℃ and 98 ℃, respec-tively; however, the structure and morphology of the samples are remained and unchanged Some of the water in the samples is lost at 230 ℃, resulting in a structural fold in the structure of palygorskite Residual water in the samples is lost at 481 ℃ and hydroxyls are lost at 595 ℃, degrading the channel structure, but the ribbon-like structure and morphology of palygorskite are retained The mor-phology of palygorskite fibers is curved after heat treatment over 800 ℃, and the structure is transformed from a crystal structure to an amorphous structure Then an exothermic reaction occurs at 827 ℃, and two new phases of cristobalite and enstatite are formed, which is similar to the sintering state at 1 000 ℃

Properties and microstructure of polymer modified mortar based on different acrylate latexes

Abstract: Two polymer latexes were employed to investigate the impacts of polymer on various properties of polymer modified mor- tars.With varied polymer additions,the mechanical properties of mortars as well as their slumps in the flesh state were measured. Semi-adiabatic temperatures of mortar during setting were monitored to study the influences of polymer latexes on the hydration process of cement.Scanning electron microscopy was used to observe the microstructure of fresh and hardened mortars.It is clearly indicated that the mechanical properties of hardened mortars are significantly enhanced due to the incorporation of polymer with the cement hydrates.Direct observation on fresh cement paste by environmental scanning electron microscopy gives solid proof that polymer particles are adsorbed by cement grains shortly after mixing,which is considered to account for the improved flowability of flesh mortar and the retardation effect on cement hydration.