Study on Hydration Mechanism of Phosphoaluminate Cement

2011 ◽  
Vol 675-677 ◽  
pp. 701-704
Author(s):  
Peng Liu ◽  
Zhi Wu Yu ◽  
Ling Kun Chen ◽  
Zhu Ding
Keyword(s):  
Portland Cement ◽  
Electrochemical Impedance ◽  
High Strength ◽  
Heat Evolution ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Scanning Microscope ◽  
Hydration Mechanism ◽  
Calcium Phosphorus ◽  
Electron Scanning Microscope

Phosphoaluminate cement (PAC) is a kind of new cementitious material which has many special properties compared to Portland cement (PC). PAC sets quickly and develops early-high strength. In order to investigate the hydration mechanism, the hydration products and microstructure of PAC were studied with x-ray diffraction (XRD), electron scanning microscope (SEM) and electrochemical impedance spectroscopy (EIS). Heat evolution of PAC was also measured. The results show that the hydration mechanism of PAC is different from Portland cement, which is caused by the special minerals including CxP, CA(P), phase L, and so on. The main hydration products of PAC are calcium phosphorus aluminates hydrate (C-A-P-H), calcium phosphate hydrate (C-P-H), aluminates hydrate (C-A-H), the corresponding hydration microcrystal as well as gels. Also, there is no calcium hydroxide produced during hydration. The hydration procedure of PAC is divided into four stages which are dissolution and induction, acceleration, deceleration, stabilization.

scholarly journals Molecular-field Molecular-field Study on Sn Substituted Yttrium Iron Garnet

2018 ◽  
Vol 34 (1) ◽  
Author(s):  
Nguyen Duong
Keyword(s):  
Sol Gel ◽  
Site Occupancy ◽  
Molecular Field ◽  
X Ray Diffraction ◽  
Scanning Microscope ◽  
Valence States ◽  
Two Samples ◽  
Gel Technique ◽  
Electron Scanning Microscope ◽  
Iron Garnet

Samples with the compositions Y2.9Ca0.1Fe4.9Sn0.1O12 and Y3Fe4.9Sn0.1O12 were prepared by using a sol-gel technique. The influence of the substituted non-magnetic cations with different valences in the structural and magnetic properties was studied. X-ray diffraction and field-emission electron scanning microscope techniques were used to study the crystal structure and morphology. Magnetization curves in fields up to 10 kOe and in temperature range from 80 K to 570 K were measured by means of a vibrating sample magnetometer. Saturation magnetization as a function of temperature of the two samples was analyzed based on the molecular-field theory from that models for site occupancy and valence states of cations in the crystal structures were derived.

Research on the Hydration Mechanism of Portland Cement with Magnesium Slag

2014 ◽  
Vol 576 ◽  
pp. 57-62 ◽  
Author(s):  
Jun Ping Deng ◽  
Xiao Liang Wang ◽  
Yi Ping Guo
Keyword(s):  
Portland Cement ◽  
Industrial Waste ◽  
Activity Index ◽  
Early Period ◽  
Performance Testing ◽  
Hydration Process ◽  
Hydration Products ◽  
Hydration Mechanism ◽  
Products Analysis ◽  
Strength Improvement

Magnesium slag is a kind of industrial waste during the silicothermic process for magnesium reduction which has potential hydration activity. By adding 20% to 50% of magnesium slag into Portland cement, the influence principle of the additive amount of magnesium slag on the pozzolanic activity is investigated through performance testing and hydration products analysis. During the early period of hydration process, the strength of pozzolanic effectiveness ratio weakens with the increasing additive amount of magnesium slag, while during the later period of hydration process with the additive amount of magnesium slag less than 40%, the strength of pozzolanic effectiveness ratio increases with increasing additive amount of magnesium slag. The activity index of magnesium slag increases with the increase of period and additive amount, and the strength brought by hydration of magnesium slag is a key source of the strength improvement of Portland cement with magnesium slag.

Effect of Aluminum Insertion Material on the Properties of AAC

2016 ◽  
Vol 703 ◽  
pp. 406-410
Author(s):  
Yun Feng Pan ◽  
Wan Ming Huang ◽  
Ya Qing Jiang ◽  
Qiang Song
Keyword(s):  
Volume Ratio ◽  
High Strength ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Hydration Degree ◽  
Scanning Electron Microscope Analysis ◽  
X Ray ◽  
Electron Microscope Analysis ◽  
Aerated Concrete ◽  
Scanning Electron

Study on the compressive strength, shrinkage and effect of aluminum insertion materials on the hydration products of Autoclaved Aerated Concrete (AAC). The types and properties of hydration products are studied by X-Ray Diffraction Analysis (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscope analysis (SEM) and so on. The results showed that the strength and the shrinkage resistance capability of the product could be improved effectively. Al3+successfully doped into C-S-H gel and tobermorite crystals, then replaced si4+of tobermorite and formed the system of C-A-S-H. Tobermorite in aluminum insertion aerated concrete is smaller and more compact. All hydration products interlace to form a whole, then the structure turns denser. Low porosity, high crystal gel volume ratio and high hydration degree are the key of the high strength aluminum insertion aerated concrete. Aluminum insertion materials improve the performance of the products.

Resistivity Study on Early Hydration Process of Phosphoaluminate Cementitious Material

2009 ◽  
Vol 79-82 ◽  
pp. 95-98 ◽  
Author(s):  
Ming Zhang ◽  
Zhu Ding ◽  
Feng Xing ◽  
Peng Liu
Keyword(s):  
Resistivity Measurement ◽  
Heat Evolution ◽  
Hydration Process ◽  
Early Age ◽  
Hydration Products ◽  
Microstructure Formation ◽  
Time Curve ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Acceleration And Deceleration

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.

Synthesis and Characterization of Magnetic Nanoparticles using polyvinylpirrolidone as stabilizer

MRS Advances ◽  
2017 ◽  
Vol 2 (49) ◽  
pp. 2769-2773
Author(s):  
Morales P. Patricio ◽  
Moncayo H. José María ◽  
García R. Miguel ◽  
Santoyo S. Jaime
Keyword(s):  
Magnetic Nanoparticles ◽  
X Ray Diffraction ◽  
Scanning Microscope ◽  
X Ray ◽  
Iron Salts ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Coprecipitation Technique ◽  
Electron Scanning Microscope

ABSTRACTMagnetic nanoparticles were obtained by chemical coprecipitation technique from aqueous solutions of iron salts, the synthesis was carried out in an alkaline medium, obtaining magnetic nanoparticles of around 2-10 nm in size. The nanoparticles obtained were stabilized with polyvinylpirrolidone (PVP), the particle size was measured by transmission electron microscopy (TEM), the crystal structure of the magnetic nanoparticles obtained was verified by X-ray diffraction (DRX). The chemical composition of the nanoparticles powder was investigated using electron scanning microscope with energy dispersive X-ray spectroscopy (EDX) equipment. Optical properties as absorption was studied by UV-Vis spectroscopy.

scholarly journals Influence of Fly Ash on Mechanical Properties and Hydration of Calcium Sulfoaluminate-Activated Supersulfated Cement

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2514
Author(s):  
Zhengning Sun ◽  
Jian Zhou ◽  
Qiulin Qi ◽  
Hui Li ◽  
Na Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Flexural Strength ◽  
Heat Evolution ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Granulated Blast Furnace Slag ◽  
Compressive And Flexural Strengths

This paper aimed to report the effects of fly ash (FA) on the mechanical properties and hydration of calcium sulfoaluminate-activated supersulfated cement (CSA-SSC). The CSA-SSC comprises of 80% granulated blast furnace slag (GBFS), 15% anhydrite, and 5% high-belite calcium sulfoaluminate cement (HB-CSA) clinker. The hydration products of CSA-SSC with or without FA were investigated by X-ray diffraction and thermogravimetric analysis. The experimental results indicated that the addition of FA by 10% to 30% resulted in a decrease in the rate of heat evolution and total heat evolution of CSA-SSC. As the content of FA was increased in the CSA-SSC system, the compressive and flexural strengths of the CSA-SSC with FA after 1 day of hydration were decreased. After 7 days of hydration, the compressive and flexural strength of CSA-SSC mixed with 10 wt.% and 20 wt.% of FA rapidly increased and exceeded that of ordinary Portland cement (OPC), especially the flexural strength. Moreover, the compressive strength of CSA-SSC mixed with 30 wt.% of FA after 90 days of hydration was close to that of OPC, and flexural strength of CSA-SSC mixed with 30 wt.% of FA after 7 days of hydration was close to that of OPC. The hydration products of the CSA-SSC and CSA-SSC mixed with FA were mainly ettringite and calcium silicate hydrate (C-S-H).

Hydration of sodium phosphate-modified high alumina cement

1994 ◽  
Vol 9 (5) ◽  
pp. 1291-1298 ◽  
Author(s):  
Weiping Ma ◽  
Paul W. Brown
Keyword(s):  
Isothermal Calorimetry ◽  
High Strength ◽  
High Alumina ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Alumina Cement ◽  
X Ray ◽  
Morphological Variations ◽  
High Alumina Cement ◽  
Sodium Phosphates

High strength can be achieved in high alumina cement (HAC) through the incorporation of phosphate-based additions at levels of 10 and 20 wt. %. In order to establish the mechanism that results in higher strength, the effects of a variety of condensed sodium phosphates (NaPO3)n, (NaPO3)n · Na2O, Na5P3O10, and (NaPO3)3 were studied. The influence of these additions on the kinetics of hydration was studied using isothermal calorimetry. The phosphatic additions enhanced reactivity, but x-ray diffraction analyses did not reveal evidence of new crystalline phosphate-containing hydration products. Microstructural evolution was examined in real time using environmental SEM, and hydration products exhibiting distinct morphologies were observed. The features exhibited ranged from amorphic to polygonal shapes, plates, and fibers. These frequently formed between crystalline calcium aluminate hydrate grains and by doing so appear to provide a means to enhance the strengths of these cements. In spite of the morphological variations, companion energy dispersive x-ray analysis showed that the compositions of these products did not vary widely. Their ranges of compositions are 52-60 wt. % Al2O3, 20-26 wt. % P2O5, and 20-24 wt. % CaO.

scholarly journals Effect of Metakaolin on Strength and Efflorescence Quantity of Cement-Based Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Tsai-Lung Weng ◽  
Wei-Ting Lin ◽  
An Cheng
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Portland Cement ◽  
Detrimental Effect ◽  
Cement Mortar ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
X Ray ◽  
Scanning Electron

This study investigated the basic mechanical and microscopic properties of cement produced with metakaolin and quantified the production of residual white efflorescence. Cement mortar was produced at various replacement ratios of metakaolin (0, 5, 10, 15, 20, and 25% by weight of cement) and exposed to various environments. Compressive strength and efflorescence quantify (using Matrix Laboratory image analysis and the curettage method), scanning electron microscopy, and X-ray diffraction analysis were reported in this study. Specimens with metakaolin as a replacement for Portland cement present higher compressive strength and greater resistance to efflorescence; however, the addition of more than 20% metakaolin has a detrimental effect on strength and efflorescence. This may be explained by the microstructure and hydration products. The quantity of efflorescence determined using MATLAB image analysis is close to the result obtained using the curettage method. The results demonstrate the best effectiveness of replacing Portland cement with metakaolin at a 15% replacement ratio by weight.

Study on Optimization Proportioning Experiment and its Hydration Mechanism of Composite Cementing Material

2011 ◽  
Vol 121-126 ◽  
pp. 418-422
Author(s):  
Jin Xiao Liu ◽  
Zeng De Yin ◽  
Wen Bin Sun
Keyword(s):  
Portland Cement ◽  
Uniform Design ◽  
Material Strength ◽  
Filling Material ◽  
Hydration Products ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Cementing Material ◽  
Aluminate Cement

This article aims at the accelerating characteristic of coal filling material. We scientifically made a series of proportion on composite-cementing material through uniform design with Portland cement, sulpho-aluminate cement and gypsums. After having testing the capability of this, we found that some certain composite-cementing material strength has been improved, both early and later strength. Furthermore, we also continually analyzed the hydration products and microstructure of composite-cementing material, then determined that early hydration products were mostly ettringites and later were C-S-H-centered and CH-centered gel.

scholarly journals An Experimental Study on Strength Characteristics and Hydration Mechanism of Cemented Ultra-Fine Tailings Backfill

2021 ◽  
Vol 8 ◽  
Author(s):  
Gan Deqing ◽  
Li Hongbao ◽  
Chen Chao ◽  
Lu Hongjian ◽  
Zhang Youzhi
Keyword(s):  
Strength Characteristics ◽  
Hydration Reaction ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Hydration Mechanism ◽  
Fine Tailings ◽  
Paste Backfill ◽  
Potential Activity ◽  
Secondary Hydration ◽  
Curing Age

In order to study the strength characteristics and hydration mechanism of the cemented ultra-fine tailings backfill (CUTB), the uniaxial compressive strength (UCS) tests of CUTB and cemented classified tailings backfill (CCTB) with cement-tailing ratio (C/T ratio) of 1:4 and 1:6 and curing ages of 3, 7, 14 and 28 days were carried out. The hydration products and morphology of the cemented paste backfill (CPB) were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the UCS of the CUTB is significant compared to the CCTB under the same conditions; the greater the C/T ratio and curing age, the greater the UCS difference value. The UCS growth curve of the CUTB is approximately S-shaped, and there is a relationship between the UCS and curing age. The ultra-fine tailings particles in the CUTB have potential activity; in the alkaline environment–generated cement hydration, active SiO2 and Al2O3 particles undergo secondary hydration reaction, resulting in no or very little Ca (OH)2 crystals generated in the CUTB, and the hydration products and morphology are also different.

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