scholarly journals The role of graphene/graphene oxide in cement hydration

2021 ◽  
Vol 10 (1) ◽  
pp. 768-778
Author(s):  
Shaoqiang Meng ◽  
Xiaowei Ouyang ◽  
Jiyang Fu ◽  
Yanfei Niu ◽  
Yuwei Ma
Keyword(s):  
Graphene Oxide ◽  
Cement Paste ◽  
Cement Hydration ◽  
Isothermal Calorimetry ◽  
High Mobility ◽  
Nucleation And Growth ◽  
Early Hydration ◽  
Mobility Of Ions ◽  
Cement Surface

Abstract Graphene (G) and graphene oxide (GO) have been shown to significantly improve the mechanical properties of cement-based materials. In this study, the effect of the G/GO on cement hydration was investigated. First, the zeta potential of G/GO in simulated solutions was tested, and the interaction between G/GO’s surface and Ca2+ was explored. Subsequently, scanning electron microscopy was used to observe the morphology of C–S–H nucleation and growth on the cement surface in the cement paste containing G/GO. Furthermore, XRD and TGA analyses were carried out on the hydration products of the sample. At last, isothermal calorimetry was applied to investigate the influence of G/GO on the early hydration of cement. The results showed that the addition of G/GO significantly accelerates C–S–H nucleation and growth on the cement surface. It is indicated that the high mobility ions derived by G/GO in the cement paste dominate the reason for the accelerated hydration of cement. The presence of G, especially GO, facilitates the mobility of ions, especially Ca2+, thus enhances the interaction between the cement surface and the ions. This strong interaction promotes the C–S–H nucleation and growth, and therefore, the hydration of the cement.

scholarly journals Basic creep of cement paste at early age - the role of cement hydration

2019 ◽  
Vol 116 ◽  
pp. 191-201 ◽  
Author(s):  
Mateusz Wyrzykowski ◽  
Karen Scrivener ◽  
Pietro Lura
Keyword(s):  
Cement Paste ◽  
Cement Hydration ◽  
Basic Creep ◽  
Early Age

scholarly journals Influences and Mechanisms of Nano-C-S-H Gel Addition on Fresh Properties of the Cement-Based Materials with Sucrose as Retarder

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2345 ◽  
Author(s):  
Deyu Kong ◽  
Guangpeng He ◽  
Haiwen Pan ◽  
Yuehui Weng ◽  
Ning Du ◽  
...  
Keyword(s):  
Cement Paste ◽  
Cement Hydration ◽  
Diffusion Rate ◽  
Protective Layer ◽  
Xrd Analysis ◽  
Nucleation And Growth ◽  
Fresh Properties ◽  
Retarding Effect ◽  
3D Network ◽  
Cement Based Materials

Influences and mechanisms of chemically synthesized nano-C-S-H gel addition on fresh properties of the cement-based materials with sucrose as a retarder were investigated in this study. The results showed that the flow value of the fresh cement paste was gradually but slightly reduced with increasing nano-C-S-H gel addition due to its fibrous but well-dispersed characteristic in both water and cement paste. The semi-adiabatic calorimetry testing results verified that incorporation of nano-C-S-H gel could greatly mitigate the retarding effect of sucrose on cement hydration. The total organic carbon (TOC) indicated that the addition of the nano-C-S-H gel helps to reduce adsorption of the sucrose molecules into the protective layer, thus the semi-permeability of the protective layer was less reduced and that is why the addition of the nano-C-S-H gel can mitigate the retardation caused by the sucrose. Through XRD analysis, it was found that the CH crystals are more prone to grow along the (0001) plane with larger size in the paste with nano-C-S-H addition before the induction period starts, because the C-S-H nanoparticles can form 3D network to slow down the diffusion rate of the released ions and eliminate the convection in the paste, thus suppress the 3D nucleation and growth of the CH crystals. The XRD analysis also indicated a refinement of the ettringite crystals in the paste with sucrose addition, but introduction of nano-C-S-H gel did not show further refinement, which was also verified by the SEM observation.

The Role of Temperature on Hydration of Binary System of Metakaolin/Portland Cement

2016 ◽  
Vol 851 ◽  
pp. 51-56 ◽  
Author(s):  
Martin Boháč ◽  
Radoslav Novotný ◽  
Jakub Tkacz ◽  
Miroslava Hajdúchová ◽  
Martin Palou ◽  
...  
Keyword(s):  
Binary System ◽  
Portland Cement ◽  
Isothermal Calorimetry ◽  
Chemical Characterization ◽  
Exothermic Peak ◽  
Early Hydration ◽  
Different Temperatures ◽  
C 50

The role of temperature of metakaolin/Portland cement binary system was studied by isothermal calorimetry. Sample with 50 % of metakaolin replacement were monitored at 30 °C, 40 °C, 50 °C and 60 °C. Structural and chemical characterization of hardened pastes was obtained by scanning electron and Raman microscopy. Paper deals with kinetics of main exothermal reactions during early hydration of the system. Activation energies were calculated for processes related to each exothermic peak. The nature of hydration products at different temperatures was revealed by microstructural studies.

The role of admixed graphene oxide in a cement hydration system

Carbon ◽  
2019 ◽  
Vol 148 ◽  
pp. 141-150 ◽  
Author(s):  
Gang Xu ◽  
Sen Du ◽  
Jialuo He ◽  
Xianming Shi
Keyword(s):  
Graphene Oxide ◽  
Cement Hydration

Modeling cement hydration by connecting a nucleation and growth mechanism with a diffusion mechanism. Part II: Portland cement paste hydration

2016 ◽  
Vol 23 (6) ◽  
pp. 605-615 ◽  
Author(s):  
Xueyu Pang ◽  
Christian Meyer
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Growth Mechanism ◽  
Rate Constants ◽  
Cement Hydration ◽  
Diffusion Mechanism ◽  
Nucleation And Growth ◽  
Curing Temperature ◽  
Nucleation And Growth Mechanism ◽  
Portland Cement Paste

AbstractA particle-based C3S hydration model with only three rate constants developed in Part I of this study is further developed and applied to Portland cement paste hydration. Experimental data are obtained with chemical shrinkage tests of cement pastes prepared with different water to cement (w/c) ratios (0.3–0.5), and cured at different temperatures (24°C–63°C) and pressures (0.69–51.7 MPa). The proposed model produces exceptionally good fits to test data. The fitted results indicate that the entire process of cement hydration can be modeled by connecting a nucleation and growth mechanism with a diffusion mechanism. Furthermore, the results reveal that the deceleration period of cement hydration may be due to the gradual transition of the rate-controlling mechanisms of different particles. The fitted rate constants generally follow basic chemical kinetics laws in terms of their dependencies on curing temperature and pressure, and appear to be largely independent of w/c ratio.

Effects of Polycarboxylate Superplasticizers on Hydration and Microstructure of Hardened Cement Paste

2012 ◽  
Vol 487 ◽  
pp. 692-696
Author(s):  
Rui Jun Gao ◽  
Sheng Hua Lv ◽  
Qiang Cao
Keyword(s):  
Calcium Carbonate ◽  
Cement Paste ◽  
Hydration Product ◽  
Ammonium Persulfate ◽  
Radical Copolymerization ◽  
Nucleation And Growth ◽  
Hardened Cement ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
Early Hydration

Polycarboxylate (PC) superplasticizer was synthesized by radical copolymerization using ammonium persulfate (APS) as initiator at 90 °C for 5 h. The effect of PC on the hydration process and microstructure of hardened cement at different hydration ages (4 h, 1 d and 7 d) was investigated. Hydration of cement paste results show that the nucleation and growth of hydration product of ettringite (Aft) was inhibited by PC at the early hydration ages, and the generation of the hydration products of calcium hydroxide (CH) and calcium carbonate (CaCO3) was promoted at late hydration ages. SEM result indicates that PC can make the structure of hardened cement more homogeneous and more density.

scholarly journals A Study on the Effect of Ceramic Polishing Powder on the Nucleation and Growth of Hydrates in Cement Paste

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 545 ◽  
Author(s):  
Liquan Wang ◽  
Ziyang Liu ◽  
Shida Xu ◽  
Xiaowei Ouyang ◽  
Dong Ouyang ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Cement Paste ◽  
Industrial Waste ◽  
Co2 Emission ◽  
Pore Solution ◽  
Nucleation And Growth ◽  
Cement Industry ◽  
Solid Waste Disposal ◽  
Early Hydration ◽  
Potential Test

The production of cement leads to a large amount of CO2 emission. Using industrial waste slag, such as ceramic polishing powder (PP), to replace part of Portland cement can reduce the pollution caused by the cement industry and solid waste disposal. In order to use PP as a replacement for cement, its effects on the properties of cement paste need to be clarified. In this study, the effect of PP on the nucleation and growth of hydrates in cement paste at very early ages was investigated. Quartz was used as a reference. The interactions of their surface with various ions in cement paste solution, which has an important effect on the nucleation and growth of hydrates, were studied by using the zeta potential test. The morphology of the nucleus and crystal of hydrates was investigated by using SEM. The zeta potential measurements showed that the affinity of the surface of PP and quartz to ions in the pore solution of cement paste is similar. The image of SEM indicated that there is also not much difference in the crystallization of hydrates on the surfaces of PP and quartz. These evidences suggested that PP has similar surface charge properties as quartz, and its effects on the properties of cement paste are the same as that of quartz. From the viewpoint of the effect on very early hydration, PP can be used in cement paste, similar to quartz power.

Early Hydration of Activated Belite-Rich Cement

2019 ◽  
Vol 1151 ◽  
pp. 23-27 ◽  
Author(s):  
Martin Boháč ◽  
Theodor Staněk ◽  
Anežka Zezulová ◽  
Alexandra Rybová ◽  
Dana Kubátová ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Analytical Approach ◽  
Isothermal Calorimetry ◽  
Early Hydration ◽  
Cement Production ◽  
X Ray ◽  
Ft Ir ◽  
Belite Cement

Implementation of high belite cement in cement production would have strong environmental impact in reduction CO2 emissions and saving of pure limestone deposits. The goal of the study is to describe the role of alkali and C-S-H activators on hydration of high belite cement. Analytical approach for early hydration is based on combination of isothermal calorimetry, X-ray powder diffraction in-situ, DTA-TG, FT-IR.

scholarly journals The Effect of Sodium Gluconate on Pastes’ Performance and Hydration Behavior of Ordinary Portland Cement

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xingdong Lv ◽  
Jiazheng Li ◽  
Chao Lu ◽  
Zhanao Liu ◽  
Yaosheng Tan ◽  
...  
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cement Hydration ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Heat Evolution ◽  
Curing Temperature ◽  
Sodium Gluconate ◽  
Early Hydration ◽  
Negative Effect

The goal of this paper provides better understanding of the effect of sodium gluconate (SG) on ordinary Portland cement (OPC) hydration behavior. Pastes’ performances of ordinary Portland cement, including setting time at 20°C and 35°C curing temperature, mechanical strength, fluidity, and zeta potential are studied. Furthermore, the effects of SG on cement hydration behaviors are investigated by the means of isothermal calorimetry measurements, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that SG is difficult to maintain significant retarding effect at the temperature of 35°C compared to that at the temperature of 20°C. SG is able to reduce the cement cumulative hydration heat and delay the occurrence time of heat evolution peak in a certain extent, but it has little impact on reducing the cement evolution rate peak. The effects of SG on mechanical properties and dispersion properties of cement depend on its dosages. Specifically, the positive effect occurs when the addition dosage is less than 0.15% (i.e., by cement weight), but the negative effect emerges if the addition dosages exceed this limitation. Similarly, SG plays different roles on cement hydration at different hydration periods. It inhibits the hydration of C3S and the formation of portlandite (CH) at the early hydration period. On the contrary, it promotes the C3S hydration when hydration time is beyond 1 d. Meanwhile, SG also plays different roles on cement hydration at different dosage additions. Specifically, SG promotes ettringite (AFt) formation at the dosage less than 0.06%, but it inhibits AFt formation at the dosage more than 0.06%.

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