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1
Matysík, Michal, Tomáš Vymazal und 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.
2
Liu, Zhiyong, Dong Xu und Yunsheng Zhang. „Experimental Investigation and Quantitative Calculation of the Degree of Hydration and Products in Fly Ash-Cement Mixtures“. Advances in Materials Science and Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/2437270.
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To explore the hydration process of fly ash-cement blended mixtures, the degrees of the fly ash and cement reactions as well as the content of nonevaporated water were determined at various water to binder ratios, curing ages, and fly ash incorporation amounts. An equation describing the relationship between the degree of hydration and the effective water to binder ratio was established based on the experimental results. In addition, a simplified scheme describing a model of the degree of reaction in fly ash-cement mixtures is proposed. Finally, using reaction stoichiometry, quantitative equations for the hydration products of fly ash-cement blended pastes are proposed by considering the hydration reactions of fly ash and cement as well as their interactions. The predicted results of the enhanced degree of cement hydration, content of calcium hydroxide (CH), and porosity are consistent with the experimental data.
3
Liu, Reng Guang, und Pei Yu Yan. „Study on Hydration Degree of Portland Cement-Slag Complex Binders“. Key Engineering Materials 539 (Januar 2013): 172–77. http://dx.doi.org/10.4028/www.scientific.net/kem.539.172.
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Abstract. The hydration degree of Portland cement-slag complex binders was investigated by hydration heat, chemically bound water amount, EDTA selective dissolution and mortar compressive strength. Different hydration degree of complex binders was obtained with different methods. Hydration heat and EDTA method indicated that reaction degree of slag was much lower than cement and the total reaction degree of complex binders was also lower than neat cement. However, chemically bound water amount and mortar compressive strengths of complex binders blended with slag within certain limit were higher than neat cement at late age.
4
Li, Xiang, Hua Quan Yang und Ming Xia Li. „Assessment of Hydration Degree of Cement in the Fly Ash-Cement Pastes Based on the Calcium Hydroxide Content“. Advanced Materials Research 875-877 (Februar 2014): 177–82. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.177.
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The hydration degree of fly ash and the calcium hydroxide (CH) content were measured. Combined with the equilibrium calculation of cement hydration, a new method for assessment of the hydration degree of cement in the fly ash-cement (FC) pastes based on the CH content was developed. The results reveal that as the fly ash content increase, the hydration degree of fly ash and the CH content decrease gradually; at the same time, the hydration degree of cement increase. The hydration degree of cement in the FC pastes containing a high content of fly ash (more than 35%) at 360 days is as high as 80%, even some of which hydrates nearly completely. The effect of water-cement ratio to the hydration degree of cement in the FC pastes is far less distinct than that of the content of fly ash.
5
Park, Ki-Bong, Yi-Sheng Wang und Xiao-Yong Wang. „Property Analysis of Slag Composite Concrete Using a Kinetic–Thermodynamic Hydration Model“. Applied Sciences 11, Nr. 16 (04.08.2021): 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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Lei, Bin, Lang Wu und Gu Quan Song. „Cement Hydration Kinetics Research Based on the Multi-Phase Hydration Model“. Advanced Materials Research 168-170 (Dezember 2010): 26–30. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.26.
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Based on the multi-phase hydration dynamic model, taking into account the factors such as chemical composition of cement, curing temperature, water-cement ratio, the final hydration degree and fineness of cement, a theoretical hydration kinetics equation is established in this paper. It can be used to predict the hydration rate increases with the change of hydration degree. The results showed that: water-cement ratio will accelerate the phase boundary reaction, while not influence the early crystallization of nucleation and crystal growth; temperature can accelerate the hydration process, while it can not change the ultimate hydration degree.
7
Zhang, Deng Xiang, und Wei Jun Yang. „A Simple Model of Predicting the Degree of Hydration of Concrete Using Artificial Neural Networks“. Advanced Materials Research 168-170 (Dezember 2010): 412–17. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.412.
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Prediction of degree of hydration of concrete is very important on research of crack-resistance capability and durability of the structure. This article studied the relationship between degree of hydration and strength of concrete based on a large number of references, the results show that the compressive strength of concrete is closely related with the degree of hydration, and the correlation function is a function of water-cement ratio and has nothing to do with the temperature. The hydration degree and compressive strength of ordinary concrete is linear correlation, and the prediction model of degree of hydration of concrete was proposed based on BP Artificial Neural Networks.
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Petrova, N., L. Filizova und G. Kirov. „Binary cation exchange in clinoptilolite involving K+, Na+ , Ba2+ and Ca2+ at 30 and 95°C: a calorimetric study“. Clay Minerals 46, Nr. 2 (Juni 2011): 251–59. http://dx.doi.org/10.1180/claymin.2011.046.2.251.
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AbstractA binary ion exchange of cationic pairs involving K, Na, Ba and Ca in clinoptilolite was investigated calorimetrically. The selected cations included two pairs equal in charge and two pairs similar in size. The heats of ion exchange and the degrees of exchange were determined at 30 and 95°C. The data obtained are discussed with respect to cationic interactions in the clinoptilolite structure and hydration characteristics (heats of hydration and hydration numbers) of competing cations in the solution. No correlation was found between the heat effects and the degree of exchange. The heat of exchange depends mainly on the difference between the hydration heats of the cations in the solution, whereas the degree of exchange depends on their positioning over the extraframework sites in the clinoptilolite structure. The heats of ion exchange are lower at 95°C than those measured at 30°C, which is due to a decrease of the hydration number with increasing temperature. In all cases the degree of exchange increases with increasing temperature.
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Barbir, Damir, und Pero Dabic. „Influence of Zinc-Saturated Zeolite on Portland Cement Hydration Kinetics“. Advances in Materials Science and Engineering 2022 (03.08.2022): 1–7. http://dx.doi.org/10.1155/2022/6576263.
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This work examines the influence of zeolite saturated with zinc (SZ) on the early hydration of Portland cement. The measurements and results indicate that the microcalorimetric method allows continuous observation and determination of SZ’s influence on kinetic processes in the early stages of hydration. According to the total heat released after 48 hours of hydration, higher SZ content results in lower heat values, while the maximum hydration occurs earlier. As SZ proportion increases, the rate of heat release and the degree of hydration decrease. Measured hydration degrees differ significantly from the calculated values when SZ is added to Portland cement, especially later in the hydration process.
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Bach, Quoc Si. „Investigation of Blended Cement Hydration in the Reactive Powder Concrete with Increasing Levels of Silica Fume Addition“. Applied Mechanics and Materials 889 (März 2019): 304–12. http://dx.doi.org/10.4028/www.scientific.net/amm.889.304.
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Hydration is a chemical reaction in which the major compounds in cement form chemical bonds with water molecules and become hydration products. By the process of hydration Portland cement mixed with sand, gravel and water produces the synthetic rock we call concrete. The Therefore, the concrete properties always accompanies with the hydration degree of cement. This paper presents some experimental test results on how silica fume affects the cement hydration in cement pastes of the Reactive Powder Concrete as increasing levels of silica fume addition with the content from 0% to 30% of cement mass. The hydration process of cement/silica fume paste was followed from the estimation of heat of hydration, rate of heat evolution, of binder pastes obtained by isothermal calorimetry (TAM-Air). In addition, the portlandite content, the hydration degree of pure cement, reaction degree of binder paste as well as reaction degree of silica fume were investigated. The quantitative assessment on these characteristics are due to the simulation of the hydration of Portland cement pastes containing silica fume.
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Rao, Chun Hua, Lang Wu und Bin Lei. „Cement Hydration Models Research Based on Composition Content of each Phase of Minerals“. Applied Mechanics and Materials 204-208 (Oktober 2012): 3639–43. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3639.
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Abstract: Based on the cement hydration kinetics model proposed by R.Berliner, taking into account the factors such as each chemical phase of minerals, curing temperature, water-cement ratio, the final hydration degree and fineness of cement, a theoretical hydration kinetics equations was established in this paper. It can be used to predict the hydration rate and the change of hydration degree.
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Deboucha, Walid, Nordine Leklou und Abdelhafid Khelidj. „Hydration degree development of blast furnace slag blended cement pastes using thermogravimetric Analysis (TGA)“. MATEC Web of Conferences 163 (2018): 04001. http://dx.doi.org/10.1051/matecconf/201816304001.
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The hydration degree assessment of slag blended cement pastes with three different replacement levels (10, 20 and 40%) and two finenesses (400 and 500 m2/kg) was investigated. The hydration degree was evaluated by using a modified TG method suggested by Deboucha et al., 2017. This method builds on the activity coefficient concept, which makes it possible to assume the amount of mineral additives that contribute to hydration reactions as well as cement. Results showed that the efficiency of blast furnace slag in developing hydration degree was conditioned by its level of replacement and fineness.
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Wu, Lang, Bing Yan und Bin Lei. „Cement Hydration Kinetics Research Based on Center-Particles Hydration Model“. Applied Mechanics and Materials 204-208 (Oktober 2012): 3634–38. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.3634.
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Abstract: Based on the center-particles hydration dynamic model proposed by Park, a micro-structural hydration model of Portland cement that was built considering the decrease of the hydration rate due to the reduction of free water and the reduction of the interfacial area of contact between the free water and the hydration products. It can be used to predict the variation relationship of the hydration rate increases with the change of hydration degree. The results showed that: the revised model can simulate the variation curve of the cement hydration speed with hydration degree in this paper and the model results agree well with the experimental results.
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Aqil, Mohammed, Lahcen Bahi, Latifa Ouadif, Siham Belhaj und Raounak Edderkaoui. „The influence of curing temperature, plastic additives and polypropylene fibers on the mechanical behaviour of cementitious materials“. E3S Web of Conferences 150 (2020): 02012. http://dx.doi.org/10.1051/e3sconf/202015002012.
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An experimental company was carried out to better understand the influence of curing temperature on the mechanical behaviour of cementitious materials, particularly compressive strength, the study focused on two types of mortars, the first containing polypropylene fibers while the second contains a proportion of PVC-type plastic grains from industrial waste, the hydration kinetics of the different components of the formulated mortar has been characterized by the isothermal calorimetric test, thus a history of the hydration degrees has been established, Afterwards, an attempt was made to correlate the compressive strength with the evolution of the degree of hydration for the different formulations, based on the results obtained, it is clearly observable that the compressive strength evolves with the degree of hydration and that the specimen containing the polypropylene fibers has the best mechanical performance with respect to compression.
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Xu, Li Wei, und Jian Lan Zheng. „Influence of the Fly-Ash Content of Concrete at Low Water-Binder Ratio on Hydration Degree of Binders and Cement“. Advanced Materials Research 250-253 (Mai 2011): 445–49. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.445.
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The hydration degree of binders and cement is investigated by measuring the adiabatic- temperature rise of concrete at low water-binder ratio with different fly-ash content. The results denote that, with a constant water-binder ratio, both of the hydration degree of binders and that of cement decrease with the increasing fly-ash content in the early stage. In a later stage, however, the hydration degree of cement increases with the increasing fly-ash content and the hydration degree of binders peaks when the fly-ash content is 35%. Fly ash is one of the mineral admixture of which high-performance concrete is made up. It brings down the rise of concrete temperature significantly and helps solve the problems of shrinkage and crack of concrete structure. Because the hydration mechanism in common concrete is different from that in concrete with low water-binder ratio, and the hydration environment is different between concrete and cement pastes, to determine the adiabatic-temperature rise of concrete directly conforms to the actual situation. The adiabatic-temperature rise, adiabatic-temperature-rise rate, hydration degree of both binders and cement are investigated by measuring adiabatic-temperature rise of concrete with different fly-ash content.
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Yan, Guoshun, Jiazheng Li, Yuqiang Lin und Xia Chen. „Difference between Internal and External Hydration of Hardened Cement Paste under Microwave Curing“. Advances in Materials Science and Engineering 2021 (31.10.2021): 1–9. http://dx.doi.org/10.1155/2021/3307325.
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In order to investigate the difference between internal and external hydration of hardened cement paste under microwave curing, a comparative study on the hydration products, hydration degree, fracture morphology, and pore structure between the inner part and outer part of hardened cement paste (Φ120 mm × 120 mm) under microwave curing was carried out by XRD-Rietveld refinement, TG-DSC, SEM, and MIP methods. The results show that the total hydration degree of the inner part is lower at early ages, but with the hydration, there is little difference in the hydration degree between inner and outer parts at later ages. Apart from granular AFt crystal formed in the inner part of hardened cement paste, there is little difference in the fracture morphology between internal and external hydration. The total porosity of the outer part is lower than that of the inner part.
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Jiang, Ya Qing, und Qian Feng Xia. „Hydration of Water Entrained Cement Paste under Saturated Condition“. Applied Mechanics and Materials 44-47 (Dezember 2010): 2249–53. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2249.
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Hydration characteristic and microstructures of water entrained cement paste with water-cement ratio (w/c) of 0.30 cured under saturated condition were studied. Degree of hydration was quantified by loss on ignition (LOI) measurements and BSE imaging. Volume of capillary pore of the hydrated paste was evaluated by using scanning electron microscopy. Degree of hydration of internally cured cement paste under saturated condition is higher than that of control paste without water entrained. A reduction of volume of capillary pore is obtained for the promotion of cement hydration. Quantity of entrained water is a time dependent function at early age in the presence of continuous external water supplying. A model was proposed for evaluation degree of hydration of cement under a combination of internal curing and saturated curing, based on equivalent w/c. Experimental results indicate that internal curing can efficiently accelerate early age hydration of cement and that only 50% of theoretical entrained water is needed for mitigation chemical shrinkage and for achieving maximum degree of hydration of cement paste with low water-cement ratio.
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Fang, Yunhui, Zhijun Lin, Dongming Yan, Xiaofang Zhang, Xiuxing Ma, Junying Lai, Yi Liu, Zhanhua Chen und Zhaopeng Wang. „Study on the Effect of Polycarboxylate Ether Molecular Structure on Slurry Dispersion, Adsorption, and Microstructure“. Polymers 15, Nr. 11 (29.05.2023): 2496. http://dx.doi.org/10.3390/polym15112496.
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This study synthesized polycarboxylate superplasticizer (PCE) with varying carboxyl densities and main chain degrees of polymerization. The structural parameters of PCE were characterized using gel permeation chromatography and infrared spectroscopy. The study investigated the impact of PCE’s diverse microstructures on cement slurry’s adsorption, rheology, hydration heat, and kinetics. Microscopy was used to analyze the products’ morphology. The findings indicated that an increase in carboxyl density led to an increase in molecular weight and hydrodynamic radius. A carboxyl density of 3.5 resulted in the highest flowability of cement slurry and the most considerable adsorption amount. However, the adsorption effect weakened when the carboxyl density was the highest. Decreasing the main chain degree of polymerization led to a significant reduction in the molecular weight and hydrodynamic radius. A main chain degree of 16.46 resulted in the highest flowability of slurry, and both large and small main chain degrees of polymerization exhibited single-layer adsorption. PCE samples with higher carboxyl density caused the greatest delay in the induction period, whereas PCE-3 promoted the hydration period’s acceleration. Hydration kinetics model analysis indicated that PCE-4 yielded needle-shaped hydration products with a small nucleation number in the crystal nucleation and growth stage, while PCE-7’s nucleation was most influenced by ion concentration. The addition of PCE improved the hydration degree after three days and facilitated the strength’s later development compared to the blank sample.
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Dunn, Rachel V., und Roy M. Daniel. „The use of gas–phase substrates to study enzyme catalysis at low hydration“. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 359, Nr. 1448 (29.08.2004): 1309–20. http://dx.doi.org/10.1098/rstb.2004.1494.
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Although there are varying estimates as to the degree of enzyme hydration required for activity, a threshold value of ca . 0.2 g of water per gram of protein has been widely accepted. The evidence upon which this is based is reviewed here. In particular, results from the use of gas–phase substrates are discussed. Results using solid–phase enzyme–substrate mixtures are not altogether in accord with those obtained using gas–phase substrates. The use of gaseous substrates and products provides an experimental system in which the hydration of the enzyme can be easily controlled, but which is not limited by diffusion. All the results show that increasing hydration enhances activity. The results using gas–phase substrates do not support the existence of a critical hydration value below which enzymatic activity is absent, and suggest that enzyme activity is possible at much lower hydrations than previously thought; they do not support the notion that significant hydration of the surface polar groups is required for activity. However, the marked improvement of activity as hydration is increased suggests that water does play a role, perhaps in optimizing the structure or facilitating the flexibility required for maximal activity.
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Qiu, Xiao Lin, Yi Ren Zhou, Lang Wu und Bin Lei. „A Three Dimensional Microstructure Sphere Model of Cement Hydration“. Advanced Materials Research 900 (Februar 2014): 421–25. http://dx.doi.org/10.4028/www.scientific.net/amr.900.421.
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A microstructure kinetic model is introduced for the hydration of cementitious materials.The hydration degree is mainly controlled by chemical reaction or diffusion rate in hydrate process of cement. According to evolution of characteristic parameters in two main processes, the hydrated kinetic equations is given in the paper. The kinetic equations can simulate the main hydrated processes, and an understanding on the hydration mechanism of cement can be emphasized. Chemical reaction dominates in the early stage of hydration, diffusion rate becomes the dominating factor gradually as the hydration degree increases.
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Xu, Li Wei. „Method to Determine Reaction Degrees of Portland Cement and Fly Ash in Complex Pastes“. Advanced Materials Research 374-377 (Oktober 2011): 1657–60. http://dx.doi.org/10.4028/www.scientific.net/amr.374-377.1657.
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To determine the reaction degrees of Portland cement and fly ash in complex pastes, an experiment of hydration degree for composite pastes, hydrochloric acid dissolution method for fly ash and solution heat method for cement is applied. It is shown from the test that a rather precise result has been obtained by the combined method. The hydration degrees of cement and fly ash in composite pastes agree well with those from theoretical analysis.
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Zhang, Hongguang, Wenya Yang, Qiling Luo und Wu-Jian Long. „Mechanical Properties and Hydration Degree of Magnesium Potassium Phosphate Cement Modified by Sintered Silt Ash“. Materials 16, Nr. 21 (02.11.2023): 7010. http://dx.doi.org/10.3390/ma16217010.
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The effective utilization rate of river-dredged silt was extremely low, and common disposal methods such as dumping it into the ocean have already threatened the ecological environment. To demonstrate that dredged silt can be used as a mineral admixture to modify magnesium potassium phosphate cement (MKPC), the mechanical properties and hydration degree of sintered silt ash (SSA)-blended MKPC in the early stage of hydration were studied systematically in this paper, with MKPC as the reference group. The mechanical experiment results showed that in the process of increasing the SSA content to 25%, the compressive strength first increased and then decreased. Among the samples, the compressive strength of cement aged by 1d and 3d with 15% content was the highest, which increased by 11.5% and 17.2%, respectively, compared with the reference group. The setting time experiment found that with the increase in SSA content, the hydration reaction rate of MKPC slowed down significantly. Its effect of delaying hydration was most obvious when the SSA content was 10–15%. The X-ray diffraction pattern showed that there was no large amount of new crystalline substances formed in the hydration product. The results obtained by scanning electron microscopy show that the microstructure tended to be denser and the hydration products tended to be plump when the SSA content was in the range of 0–15%. The non-contact electrical resistivity experiment showed that the addition of SSA delayed the early hydration of MKPC. Combined with the above experiment results, it was found that when the content of SSA was less than 15%, it not only delayed the early hydration of MKPC, but also deepened its hydration degree.
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Reiterman, Holčapek, Davidová, Jaskulski und Keppert. „Estimation of Hydration Degree of Blended Cements with the Help of k-Values“. Materials 12, Nr. 15 (29.07.2019): 2420. http://dx.doi.org/10.3390/ma12152420.
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The growing utilization of various mineral additives in the building industry has caused concern worldwide to reduce the emissions of carbon dioxide from Portland cement (OPC) production. The present paper is focused on the determination of the degree of hydration of blended binding systems based on Portland cement. Blast furnace slag, fly ash, and ceramic powder are used in the study; they are applied by 12.5 wt.% up to 50% of OPC replacement. The evolution of the hydration process is monitored using thermogravimetry in selected time intervals to determine the degree of hydration; its ultimate value is obtained from numerical estimation using the Michaelis-Menten equation. However, due to the application of active mineral additives, the correction in terms of equivalent binder is conducted. Corrected values of the degree of hydration exhibit good fit with compressive strength.
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Zhang, Xiong, und Jun Chang. „Effect of Different Hydration Time on Carbonation Degree and Strength of Steel Slag Specimens Containing Zeolite“. Materials 13, Nr. 17 (03.09.2020): 3898. http://dx.doi.org/10.3390/ma13173898.
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Steel slag partially substituted by zeolite (SZ) was beneficial for improving the compressive strength and carbonation degree of SZ specimens after a combined curing (hydration and then carbonation) process due to pozzolanic reaction between them. By previous work results, the zeolitic substitution ratios of 5 wt.% and 15 wt.% in steel slag specimens (SZ5 and SZ15) gained the optimum compressive strength and carbonation degree, respectively, after 1 day hydration and then 2 h carbonation. This study investigated the effect of previous hydration time (1, 3, 7, 14, and 196 days) on carbonation degree and strength of SZ specimens after subsequent carbonation curing. Two zeolitic substitution ratios (5 wt.% and 15 wt.%) were selected and pure steel slag specimens were also prepared as controls. Compressive strength results revealed that the optimum hydration curing time was 1 day and the optimum zeolitic substitution ratio was 5 wt.%. The pozzolanic reaction happened in SZ specimens was divided into early and late pozzolanic reaction. In the late hydration, a new mineral, monocarboaluminate (AFmc) was produced in SZ15 specimens, modifying the carbonation degree and strength further. And the mechanism of pozzolanic reaction in early and late hydration in SZ specimens was explained by several microscopic test methods.
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Wu, Cheng Zhu, Yong He Liang, Yu Cheng Yin, Man Fei Cai, Jian Hua Nie und 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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Li, Hua, Jia Ping Liu, Qian Tian und Shou Zhi Zhang. „Hydration Kinetics and Microscopic Analysis of Calcium Oxide Expansion Clinker“. Applied Mechanics and Materials 477-478 (Dezember 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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Wang, Xiao-Yong. „Kinetic Hydration Heat Modeling for High-Performance Concrete Containing Limestone Powder“. Advances in Materials Science and Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/4090265.
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Limestone powder is increasingly used in producing high-performance concrete in the modern concrete industry. Limestone powder blended concrete has many advantages, such as increasing the early-age strength, reducing the setting time, improving the workability, and reducing the heat of hydration. This study presents a kinetic model for modeling the hydration heat of limestone blended concrete. First, an improved hydration model is proposed which considers the dilution effect and nucleation effect due to limestone powder addition. A degree of hydration is calculated using this improved hydration model. Second, hydration heat is calculated using the degree of hydration. The effects of water to binder ratio and limestone replacement ratio on hydration heat are clarified. Third, the temperature history and temperature distribution of hardening limestone blended concrete are calculated by combining hydration model with finite element method. The analysis results generally agree with experimental results of high-performance concrete with various mixing proportions.
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Grebenkina, N. S., N. A. Kontarov und N. V. Yuminova. „THE STUDY OF INFLUENZA VIRUS NEURAMINIDASE HYDRATION DEGREE“. Russian Journal of Infection and Immunity 7, Nr. 4 (01.01.2017): 405–8. http://dx.doi.org/10.15789/2220-7619-2017-4-405-408.
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Chidiac, S. E., und M. Shafikhani. „Cement degree of hydration in mortar and concrete“. Journal of Thermal Analysis and Calorimetry 138, Nr. 3 (16.09.2019): 2305–13. http://dx.doi.org/10.1007/s10973-019-08800-w.
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Wennerström, H., und E. Sparr. „Thermodynamics of membrane lipid hydration“. Pure and Applied Chemistry 75, Nr. 7 (01.01.2003): 905–12. http://dx.doi.org/10.1351/pac200375070905.
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Zwitterionic or polar lipids that form lamellar phases swell in the presence of water to take up between 10 and 30 water molecules per lipid. The degree of the water uptake depends both on the state of the alkyl chains, liquid or solid, and on the nature of the polar group. The swelling behavior has been extensively characterized on the free-energy level through measuring the relation between the chemical potential of the water and the degree of swelling. In spite of the extensive studies of this type, consensus is still lacking concerning the molecular mechanism causing the swelling. The two main ideas that explain the existence of the effectively repulsive force between two opposing bilayers are (i) a water structure effect and (ii) thermal excitations of the lipid molecules. The first is from a thermodynamic perspective caused by a negative partial molar enthalpy of the water, whereas for the second, the repulsion is caused by positive entropy.A further insight into the swelling behavior is obtained by simultaneously measuring the partial molar free energy and the partial molar enthalpy using a twin double calorimeter. Such measurements show for binary lipid–water and for ternary lipid –cholesterol –water systems that the first four water molecules enter the bilayer driven by a favorable enthalpic interaction, whereas for higher water contents, the partial free energy and the partial enthalpy have opposite signs. In spite of the fact that the partial free energy varies with water content in a similar way, the partial enthalpies depend strongly on the nature of the lipid sample. Thus, it is obvious that a molecular interpretation of the enthalpy values has to involve the lipid degrees of freedom. This is a strong indication that the interpretation of the free energies should also include the same degrees of freedom. This gives experimental evidence in favor of an interpretation of the molecular mechanism causing the swelling that involves changes in the thermal excitation of the lipid degrees of freedom.
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Siyao, Huang, Xu Mingbiao, Xu Peng, Zhang Yu und Wang Xinying. „Composite Hydration Process of Clay Minerals Simulating Mineral Clay Components and Influence Mechanism of Cations“. Energies 15, Nr. 20 (13.10.2022): 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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Li, Z., J. M. Vandenbossche, A. T. Iannacchione und A. Vuotto. „Characterization of Oil Well Cement Performance during Early Hydration under Simulated Borehole Conditions“. SPE Journal 26, Nr. 06 (25.02.2021): 3488–504. http://dx.doi.org/10.2118/205350-pa.
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Summary Experiments on oil well cement (OWC) slurries were performed using the newly developed laboratory-scale wellbore simulation chamber (WSC). The WSC can simulate hydrostatic pressure reduction in the cemented annulus and possible gas migration under representative conditions. Forensic analysis shows that pressurized fluids can result in porous cement and gas channeling during cement slurry gelation. The effects of different factors on slurry pore pressure were also studied, including formation permeability, initial overburden pressure (OBP) representing the depth of interest, wellbore temperature, water/cement (w/c) ratio, cement composition, and the use of a calcium chloride (CaCl2)-based accelerator. By analyzing the temperature history of hydrating cement using degree of hydration, the evolution of cement hydration was characterized for slurry designs cured at different hydration rates. This provides the opportunity to parameterize the slurry designs and other important factors associated with wellbore conditions.
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Wang, Ru, und Xiaoxin Shi. „Influence of Styrene-Acrylic Ester Dispersion on the Early Hydration of Cement“. Advances in Materials Science and Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/970298.
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Early hydration of cement in the presence of styrene-acrylic ester (SAE) dispersion was investigated, and the hydration heat, hydration degree, and hydrates were analyzed using isothermal calorimeter, XRD, and ESEM. The results show that SAE dispersion prolongs the induction period, postpones and shortens the accelerating period, and inhibits the decelerating and stable periods of cement hydration. The hydration heat and hydration degree of cement in the presence of SAE dispersion are less than those of the control. SAE dispersion inhibits the formation of C4AH13and thus AFt, and more SAE dispersion brings stronger influence, but it enhances the stability of AFt. AFt generation during the early hydration period is controlled gradually by the reaction of C4AH13generation with increasing SAE dispersion, but this is controlled by the reaction of C4AH13consumption for the control paste. Besides, SAE dispersion retards and inhibits the formation of CH and C-S-H and also changes their morphology.
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Han, Xiaofeng, Hua Fu, Gege Li, Li Tian, Chonggen Pan, Chunlei Chen und Penggang Wang. „Volume Deformation of Steam-Cured Concrete with Slag during and after Steam Curing“. Materials 14, Nr. 7 (27.03.2021): 1647. http://dx.doi.org/10.3390/ma14071647.
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In order to better predict the development of shrinkage deformation of steam-cured concrete mixed with slag, a deformation-temperature-humidity integrated model test, a hydration heat test, and an elastic modulus test were performed. The effects of the steam-curing process and the content of slag on shrinkage deformation, hydration degree and elastic modulus of concrete were studied. The results indicate that during the steam-curing process, the concrete has an “expansion-shrinkage” pattern. After the steam curing, the deformation of concrete is dominated by drying shrinkage. After the addition of slag, the shrinkage deformation of steam-cured concrete is increased. The autogenous shrinkage increases by 0.5–12%, and the total shrinkage increases by 1.5–8% at 60 days. At the same time, slag reduces the hydration degree of steam-cured concrete and modulus of elasticity. A prediction model for the hydration degree of steam-cured concrete is established, which can be used to calculate the degree of hydration at any curing age. Based on the capillary tension generated by the capillary pores in concrete, an integrated model of autogenous shrinkage and total shrinkage is established with the relative humidity directly related to the water loss in the concrete as the driving parameter. Whether the shrinkage deformation is caused by hydration reaction or the external environment, this model can better predict the shrinkage deformation of steam-cured concrete.
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Li, Guo, En Li Lu, Peng Wang, Ou Geng und Yong Sheng Ji. „Influences of Initial Curing Conditions on the Microstructure of Fly Ash Cement System“. Advanced Materials Research 168-170 (Dezember 2010): 532–36. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.532.
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In order to study the influences of initial curing conditions on fly ash (FA) cement concrete durability, fly ash cement samples with 30% replacement ratio were fabricated and cured in water at 10°C, 20°C, 30°Cand 40°C for 3d, 7d, 14d and 28d respectively. Hydration degrees of fly ash at early age were measured using the selective dissolve method. Correspondingly the pore structure and morphology of FA-cement mortar and compared cement mortar were studied by using MIP and SEM methods. Then early age compressive strengths of FA-cement concrete and compared normal cement concrete were tested. Experimental results show that initial curing temperatures and ages are important factors to fly ash early age hydration degree, FA-cement system microstructure, morphology and early age compressive strength etc. High curing temperatures and longer curing time can lead higher fly ash hydration degree, and then higher compressive strength of FA-cement concrete, and make the micro-structures of fly ash-cement system denser.
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Song, Xu Yan, Jing Yun Han und Zhi Hai Gao. „Effect of Added-Calcium Thermal Activated Coal Gangue on Cement Hydration“. Applied Mechanics and Materials 71-78 (Juli 2011): 833–36. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.833.
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Through determining Ca(OH)2 content and chemically combined water content, hydration degree of cement with added-calcium thermal activated coal gangue may be analyzed. Variation of mineral composition during hydration process of system was analyzed by X-ray diffraction(XRD) method. Simultaneously, specific strength index was applied to study pozzolanic effect of activated coal gangue. The results can show high contribution of added-calcium coal gangue calcined at 1050°C for pozzolanic properties and high hydration reaction degree in this kind of activared coal gangue cement system, with fewer Ca(OH)2 content, more chemically combined water content and obviously reduced hydration product Ca(OH)2 at each age.
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Holmes, Niall, Mark Tyrer und Denis Kelliher. „Predicting Chemical Shrinkage in Hydrating Cements“. Buildings 12, Nr. 11 (14.11.2022): 1972. http://dx.doi.org/10.3390/buildings12111972.
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This paper presents a prediction of chemical shrinkage volume created during the hydration of two cements over time using a thermodynamic model. Chemical shrinkage in hydrating cements is a result of internal volume change over time within sealed conditions due to exothermic reactions during hydration and the resulting precipitation of solid hydrates. Each precipitated phase will contribute to chemical shrinkage due to their individual reactions and stoichiometric properties. As these factors (including early age, drying and autogenous nature) contribute to the overall shrinkage of concrete which may cause long-term performance problems, they are important properties to understand. The current paper presents a thermodynamic model that quantifies the chemical shrinkage volume created during the first 1000 days of hydration using the cemdata18 database and a series of discrete solid phases (DSPs) to represent C-S-H, which has not been quantified in the literature to date. DSPs account for the amorphous and poorly crystalline nature of C-S-H in cement, and its incongruent dissolution behavior of C-S-H as calcium is released in solution more so than silicon. A description of chemical shrinkage in hydrating cements is provided, along with a review of past methods used to quantify its development over time. The paper also shows the linear relationship between chemical shrinkage and the overall degree of hydration.
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Llorens, Joan, Fernando Julián, Ester Gifra, Francesc X. Espinach, Jordi Soler und Miquel Àngel Chamorro. „An Approach to Understanding the Hydration of Cement-Based Composites Reinforced with Untreated Natural Fibers“. Sustainability 15, Nr. 12 (11.06.2023): 9388. http://dx.doi.org/10.3390/su15129388.
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The use of untreated natural fibers to reinforce cementitious composites improves their environmental friendliness, resulting in a more sustainable material. Moreover, the influence of the untreated natural fibers on the hydration process of Portland cement composites presents some uncertainties. According to the literature, the most usual tests to analyze the degree of hydration of cement composites are the differential thermal and thermogravimetric analyses (TGA/dTGA). Several authors propose to analyze data methods to establish the degree of hydration of cement composites. This paper presents the TGA/dTGA test carried out on mortar samples with and without fibers at age 2, 3, 7, 14, and 28 days. The degree of hydration was calculated according to Bhatty’s method. To characterize the raw materials, the quantitative chemical was determined using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM–EDX). The main findings of this study were that the presence of untreated natural hemp fibers in the OPC composites increased the hydration degree by 9%. The presence of fibers affected the formation of several components. Thus, their presence increased the formation of monosulphate, reduced portlandite, did not affect ettringite, and increased the formation of calcite, thereby improving the sustainable footprint due to the increased CO2 fixation.
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Zhao, Wenhao, Xuping Ji, Yaqing Jiang und Tinghong Pan. „Effect of C-S-H Nucleating Agent on Cement Hydration“. Applied Sciences 11, Nr. 14 (20.07.2021): 6638. http://dx.doi.org/10.3390/app11146638.
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This work aims to study the effect of a nucleating agent on cement hydration. Firstly, the C-S-H crystal nucleation early strength agent (CNA) is prepared. Then, the effects of CNA on cement hydration mechanism, early strength enhancement effect, C-S-H content, 28-days hydration degree and 28-days fractal dimension of hydration products are studied by hydration kinetics calculation, resistivity test, BET specific surface area test and quantitative analysis of backscattered electron (BSE) images, respectively. The results show that CNA significantly improves the hydration degree of cement mixture, which is better than triethanolamine (TEA). CNA shortens the beginning time of the induction period by 49.3 min and the end time of the cement hydration acceleration period by 105.1 min than the blank sample. CNA increases the fractal dimension of hydration products, while TEA decreases the fractal dimension. CNA significantly improves the early strength of cement mortars; the 1-day and 3-days strength of cement mortars with CNA are more than the 3-days and 7-days strength of the blank sample. These results will provide a reference for the practical application of the C-S-H nucleating agent.
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Niyakovskii, A. M., V. N. Romaniuk, A. N. Chichko und Yu V. Yaczkevich. „Verification оf Non-Stationary Mathematical Model оf Concrete Hardening in Thermal Technological Installations“. Science & Technique 18, Nr. 2 (17.04.2019): 137–45. http://dx.doi.org/10.21122/2227-1031-2019-18-2-137-145.
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Thermo-technical installations consuming significant amounts of thermal energy are used in order to intensify precast and reinforced concrete production processes under industrial conditions. Despite significant progress in the study of concrete hardening in accelerated hydration devices, a prominent lack of reliable and cost-effective research and optimization methods of their operation is observed. The methods used in real production processes are mainly based on empirical dependences obtained for specific technological conditions. These methods can not always be applied for other modes and technologies. The present paper develops calculation methods based on fundamental laws that make it possible to obtain functions for evolution of concrete product hydration process. Methods of mathematical modeling permit to develop new ways directed on improvement of modes for heat treatment of concrete products and accelerated hydration technologies. The paper describes a mathematical model for calculating a hardening process of a concrete product that includes a transient three-dimensional heat conductivity equation, a function of internal heat release due to behavior of exothermic reactions of cement hydration and also a system of initial and boundary conditions. A numerical simulation for temperature and hydration coefficient of a concrete product having shape of a 0.1´0.1´0.1 m cube has been performed in the paper. Verification of the non-stationary mathematical model for calculating temperature fields and hydration degree while using experimental data on concrete product strength obtained under industrial conditions. Investigations on hydration degree function of time have shown that experimentally obtained values of compressive strength correlate with hydration coefficient and hydration rate functions of heat treatment time which are calculated on the basis of the proposed non-stationary mathematical model of concrete product hardening. Satisfactory agreement of experimental and calculated data confirms adequacy of the proposed non-stationary mathematical model for calculating temperature fields and hydration degree with accelerated heat treatment of concrete products.
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Khalil, Kh A. „Surface Characteristics of Portland Cement/Blast Furnace Slag Mixtures“. Adsorption Science & Technology 13, Nr. 6 (Dezember 1996): 461–67. http://dx.doi.org/10.1177/026361749601300602.
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The effect of the degree of hydration and amounts of granulated blast furnace slag on the surface properties of Portland cement pastes were studied. The results obtained showed that the specific surface area SBET (m2/g) and pore volume Vp (cm3/g) decreased on increasing the degree of hydration. The addition of different amounts of granulated slag effected a decrease in SBET and Vp to an extent proportional to the amount present. These results were attributed to a replacement of clinker by the amounts of slag added and the formation of hydration products.
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Ash, J. E., M. G. Hall, J. I. Langford und M. Mellas. „Estimations of degree of hydration of portland cement pastes“. Cement and Concrete Research 23, Nr. 2 (März 1993): 399–406. http://dx.doi.org/10.1016/0008-8846(93)90105-i.
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Li, Pengfei, Wei Lu, Xuehui An, Li Zhou und Sanlin Du. „Effect of Epoxy Latexes on the Mechanical Behavior and Porosity Property of Cement Mortar with Different Degrees of Hydration and Polymerization“. Materials 14, Nr. 3 (21.01.2021): 517. http://dx.doi.org/10.3390/ma14030517.
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In this study, an analysis of the influence of polymer modification on the mechanical behavior, porosity, and microstructure of mortar is carried out. Epoxy latexes contents of 5%, 10%, 15%, and 20% of cement were employed in the preparation of cement mortars based on the same workability. The specimens were subjected to dry, wet, and wet–dry curing regimes. Compressive strength, flexural strength, Mercury intrusion porosimetry (MIP), and scanning electronic microscope (SEM) tests were conducted to analyze the effect of epoxy latexes on the mechanical property and porosity of modified mortars. Based on the compressive strength test results, a quantitative method was established to calculated the degree of hydration and polymerization. The results show that the mechanical behavior and porosity property of epoxy latexes modified mortar are influenced by the degree of hydration, the degree of polymerization, and the volume changing effect of mortar. The polymerization of epoxy latexes could improve the flexural strength of the mortar. The macropores of specimens tended to decrease with the increase of the degree of epoxy latexes polymerization and cement hydration. In practical engineering, it is necessary to ensure the degree of hydration and increase the polymerization rate. Thus, the wet–dry curing regime is recommended.
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Pyzalski, Michał, Karol Durczak, Agnieszka Sujak, Michał Juszczyk, Tomasz Brylewski und Mateusz Stasiak. „Synthesis and Investigation of the Hydration Degree of CA2 Phase Modified with Boron and Fluorine Compounds“. Materials 17, Nr. 9 (26.04.2024): 2030. http://dx.doi.org/10.3390/ma17092030.
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This study investigated the effect of fluoride and boron compound additives on the synthesis and hydration process of calcium aluminate (CA2). The analysis showed that the temperature of the full synthesis of CA2 without mineralizing additives was 1500 °C. However, the addition of fluorine and boron compounds at 1% and 3% significantly reduced the synthesis temperature to a range of 1100–1300 °C. The addition of fluoride compounds did not result in the formation of fluoride compounds from CaO and Al2O3, except for the calcium borate phase (Ca3(BO3)2) under certain conditions. In addition, the cellular parameters of the synthesized calcium aluminate phases were not affected by the use of these additives. Hydration studies showed that fluoride additives accelerate the hydration process, potentially improving mechanical properties, while boron additives slow down the reaction with water. These results highlight the relevance of fluoride and boron additives to the synthesis process and hydration kinetics of calcium aluminate, suggesting the need for further research to optimize their application in practice. TG studies confirmed the presence of convergence with respect to X-ray determinations made. SEM, EDS and elemental concentration maps confirmed the presence of a higher Al/Ca ratio in the samples and also showed the presence of hexagonal and regular hydration products.
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Chen, Yanqiang, Chunxiang Qian und Hengyi Zhou. „Characterization Methods for the Effect of Microbial Mineralization on the Microstructure of Hardened C3S Paste“. Advances in Materials Science and Engineering 2020 (18.08.2020): 1–9. http://dx.doi.org/10.1155/2020/7869345.
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Microbial mineralization has a significant effect on the hydration process of cement-based materials. This paper mainly studied the characterization methods for hydration degree and hydration product of C3S in hardened paste under microbial mineralization. Quantitative X-ray diffraction (QXRD), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), and electron backscatter diffraction (EBSD) were used and compared. The results showed that microbial mineralization increased the hydration degree of T-C3S. QXRD and EBSD could be used to characterize the content of C3S, and there were few differences between the two methods. TG could accurately characterize the content of Ca(OH)2 and CaCO3 at different depths of the sample, and FT-IR could qualitatively characterize the presence of Ca(OH)2 and CaCO3.
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Liu, Lin, und Jing Chang Wang. „Test and Calculation Model of Thermal Conductivity of Concrete“. Key Engineering Materials 905 (04.01.2022): 314–19. http://dx.doi.org/10.4028/www.scientific.net/kem.905.314.
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In order to study the influence of water content and hydration degree on the thermal conductivity of concrete, based on the steady-state plate method, the influence of water content, temperature, hydration degree and other factors on the thermal conductivity of early concrete was studied, and the calculation model of thermal conductivity of early concrete was established according to the test results and influence rules. The results show that there is a linear relationship between the thermal conductivity and water content at 28d, the higher the hydration degree is, the lower the thermal conductivity of concrete is; the difference between the measured value and the calculated model value is small, and the calculation formula can meet the requirements of engineering calculation.
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Zhang, Ju, Changwang Yan, Pucun Bai, Xiaoxiao Wang, Shuguang Liu und Zhigang Liu. „Effects of Calcium Silicate Slag on Hydration of Cementitious Pastes“. Materials 12, Nr. 19 (23.09.2019): 3094. http://dx.doi.org/10.3390/ma12193094.
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Calcium silicate slag (CSS) is waste slag and it contains a large amount of beta-dicalcium silicate. This study is mainly focused on the effect of CSS on the hydration of cementitious pastes. CSS was used to partly replace cement, and composite pastes containing CSS and cement were prepared. The mineral composition and particle size distribution of CSS were characterized. The chemically combined water of the paste sample was measured at a given test age. Based on the value of chemically combined water, the hydration degree and the hydration rate of composite pastes were analyzed. The flexural strength of the samples was established. The pore structure and micromorphology of the sample were also observed. The results indicate the chemically combined water decreased, the hydration degree decreased, the hydration rate declined, and the spherical micromorphology of the calcium silicate hydrate gel was reduced after more cement was replaced by CSS in the composite pastes. Besides, the amount of pores increased, its size was bigger, and air content in the pore was higher. However, flexural strength was lower. CSS has a significant impact on the hydration of cementitious pastes, and it is thus suitable to regulate hydration.
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Zhou, Yue, Zhongping Wang, Zheyu Zhu, Yuting Chen, Linglin Xu und Kai Wu. „Impacts of Space Restriction on the Microstructure of Calcium Silicate Hydrate“. Materials 14, Nr. 13 (30.06.2021): 3645. http://dx.doi.org/10.3390/ma14133645.
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The effect of hydration space on cement hydration is essential. After a few days, space restriction affects the hydration kinetics which dominate the expansion, shrinkage and creep of cement materials. The influence of space restriction on the hydration products of tricalcium silicate was studied in this paper. The microstructure, morphology and composition of calcium silicate hydrate (C-S-H) were explored from the perspective of a specific single micropore. A combination of Raman spectra, Fourier transform infrared spectra, scanning electron microscopy and energy dispersive X-ray spectroscopy were employed. The results show that space restriction affects the structure of the hydration products. The C-S-H formed in the micropores was mainly composed of Q3 silicate tetrahedra with a high degree of polymerization. The C-S-H formed under standard conditions with a water to cement ratio of 0.5 mostly existed as Q2 units. Space restriction during hydration is conducive to the formation of C-S-H with silica tetrahedra of a high polymerization degree, while the amount of water filling the micropore plays no obvious role on the polymeric structure of C-S-H during hydration.
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Wang, Feng, Pingan Chen, Xiangcheng Li und Boquan Zhu. „Effect of Colloidal Silica on the Hydration Behavior of Calcium Aluminate Cement“. Materials 11, Nr. 10 (28.09.2018): 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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Li, Qiu Ying, Ling Chao Lu und Shou De Wang. „Effect of Gypsum on Hydration Degree and Structure of Hardened Paste of Alite-Strontium Calcium Sulphoaluminate Cement“. Advanced Materials Research 306-307 (August 2011): 1024–28. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1024.
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Synthesis conditions and performance of alite-strontium calcium sulphoaluminate cement have been studied by introducing strontium calcium sulphoaluminate into Portland cement clinker. The effects of gypsum on compressive strength, hydration degree and structure of hardened alite-strontium calcium sulphoaluminate cement paste were studied in this paper. Composition and structure of the hardened cement paste were analyzed by XRD and SEM. Results show that appropriate content of gypsum could contribute to the hydration of alite-strontium calcium sulphoaluminate cement. When gypsum content is 9%, the compressive strengths for 1d, 3d and 28d curing age are 30.7MPa, 59.5MPa and 105.5MPa, and the corresponding hydration degree are 40.4%, 57.5% and 85.8%, respectively. The hydration products of alite-strontium calcium sulphoaluminate cement are mainly ettringite (AFt), Ca(OH)2, C-S-H gel. Large amount of AFt formed at early curing age provides a sound basis for early compressive strength, and a lot of C-S-H gel generated at later curing age increases the density of the hardened paste.