scholarly journals Properties and Reaction Mechanisms of Magnesium Phosphate Cement Mixed with Ferroaluminate Cement

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2561 ◽  
Author(s):  
Liang Jia ◽  
Fangli Zhao ◽  
Jian Guo ◽  
Kai Yao
Keyword(s):  
Water Resistance ◽  
Energy Dispersive Spectrometer ◽  
Setting Time ◽  
Cementitious Materials ◽  
Magnesium Phosphate ◽  
Curing Time ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Composite Cement ◽  
Hydrated Product

A certain amount of ferroaluminate cement (FAC) was substituted for MgO during the magnesium phosphate cement (MPC) preparation to obtain the MPC–FAC composite cement. The influence of FAC on the strength, water resistance, pH, and setting time of MPC–FAC composite cement were examined. The microstructure and chemical composition were also analyzed by adopting scanning electron microscopic energy-dispersive spectrometer and X-ray diffraction, respectively. The study showed that setting time of MPC–FAC composite cement was dramatically prolonged when FAC substitution for MgO was between 30 and 40 wt %. The strength of MPC–FAC did not decrease during the early curing time (1 h and 1 d), whereas it increased during the late curing time (3, 7, and 28 days). Moreover, the existence of FAC decreased the hydrated product K-struvite during the early curing time and thus dramatically enhanced the water-resistance of MPC–FAC. With the addition of FAC, a large number of cementitious materials of AFt and AFm, as well as flocculent colloidal substances of AH3, C–S–H, and FH3, were generated during the hydration of MPC, which were filled in the internal pore of the hydrate. Thus, the internal compactness of the sample increased, while the compact protective covering layer was generated on the surface to enhance the water resistance and strength in the late curing time.

Performance of Tailing Contaminated Soils Solidified by Phosphate-Based Binder

2016 ◽  
Vol 858 ◽  
pp. 104-110 ◽  
Author(s):  
Hao Liang Wu ◽  
Yan Jun Du ◽  
Yu You Yang ◽  
M.L. Wei
Keyword(s):  
Heavy Metals ◽  
Contaminated Soils ◽  
Extraction Procedure ◽  
Mining Area ◽  
Strength Properties ◽  
Curing Time ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Unconfined Compression Test ◽  
Binder Type

This paper presents a study on soils, from the Baoshan mining site, contaminated with heavy metals and stabilized by using a new phosphate-based binder. Unconfined compression test, sequential extraction procedure, X-ray diffraction and scanning electron microscopic procedures are carried out. This study aims to explore the effects of binder type, binder content and curing time of solidified contaminated soils on leaching and strength properties of the soils contaminated with heavy metals in the mining area. The results showed that as the curing time is increased from 0 d to 28 d, the new phosphate-based binder stabilized contaminated soil underwent several changes: 1) improved the strength and 2) decreased the exchangeable Zn and Pb and increased the residual contents.

Age-Hardening Behavior of Pd-Ag-Sn-In-Zn Alloy

2014 ◽  
Vol 1028 ◽  
pp. 14-19 ◽  
Author(s):  
Hai Jun Wu ◽  
Xiao Qing Zuo ◽  
Ying Wu Wang ◽  
Kun Hua Zhang ◽  
Yu Zeng Chen
Keyword(s):  
Aging Time ◽  
Early Stage ◽  
Energy Dispersive Spectrometer ◽  
Hardness Test ◽  
Age Hardening ◽  
Aged Alloy ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic ◽  
Zn Alloy

Pd-Ag-Sn-In-Zn alloy was subjected to isothermal aging treatments at 400°C, 500°C, and 650°C. Age-hardening behaviour and related microstructure changes of the aged alloy were studied by means of hardness test, X-ray diffraction (XRD), scanning electron microscopic (SEM) and energy dispersive spectrometer (EDS). The results indicate that the hardness of the alloy reaches a highest value of 348Hv after aging at 650°C for 20min. Further increasing the aging time leads to softening. The hardening of the alloy at early stage of the age-hardening at 650°C is ascribed to the formation of lamellar (α1+ β) precipitates along the grain boundaries of α matrix. The softening of the alloy occurred by further increasing aging time is caused by the coarsening of the precipitates.

Experimental Research on the Properties of Modified MPC

2012 ◽  
Vol 450-451 ◽  
pp. 796-799 ◽  
Author(s):  
Bing Chen ◽  
Xin Yuan Yang ◽  
Ning Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Experimental Research ◽  
Water Resistance ◽  
Setting Time ◽  
Experimental Results ◽  
Magnesium Phosphate

Magnesium phosphate cement (MPC) was modified by fly ash, silica fume and re-dispersible latex powder and the properties of modified MPC, such as fluidity, setting time and compressive strength, were tested. Based on the experimental results, the contents of 50% fly ash, 10% silica fume and 2% re-dispersible latex powder were chosen to modify MPC and the water resistance of the modified MPC was studied. The experimental results showed that the addition of fly ash prolonged the setting time and significantly increased the compressive strength of MPC. The addition of silica fume improved only the water resistance of MPC. The addition of the re-dispersible latex powder prolonged the setting time and improved the water resistance of MPC.

Influence of Slag on Water Resistance of Magnesia Phosphate Cement

2015 ◽  
Vol 1096 ◽  
pp. 387-391 ◽  
Author(s):  
Zhe Wang ◽  
Yao Kun Ding ◽  
Si Rui Li
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Water Resistance ◽  
Ph Value ◽  
Hydration Product ◽  
Magnesium Phosphate ◽  
Strength Increase ◽  
Curing Conditions ◽  
Hydrated Product

Effect of different curing conditions on the mechanical properties of magnesium phosphate cement (MPC), and the water resistance of MPC was improved by adding slag, the influence of slag on component and microstructure of the hydrated product were studied in this paper. The additive amount of slag was 0% ,10% , 20%, 30% and 40% separately in the ratio of total amount of MPC. It indicates that the compressive strength and flexural strength increase by about 30%,40% when the amount of slag reaches 10% of phosphate cement, respectively , and the dissolution of some phosphate which has not reacted can be prevented when cured in water for days, it improves the pH value of the solution, so the main hydration product-MgKPO4·6H2O hard to be dissolved under alkaline environment resulting in the decreasing of porosity ,and the decrease of strength would be controlled.

scholarly journals Effect of Bagasse Fiber As the Renewable Environmentally Friendly Material on the Properties of the Waterborne Intumescent Fireproof Coating

2021 ◽  
Author(s):  
Wang Zhan ◽  
Zhongfei Ma ◽  
Zhihao Sun ◽  
Lixia Li ◽  
Zhaozhan Gu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fire Protection ◽  
Water Resistance ◽  
Energy Dispersive Spectrometer ◽  
Fire Retardant ◽  
Resistance Test ◽  
X Ray Diffraction ◽  
Char Layer ◽  
Fireproof Coating ◽  
In Fire

Abstract Bagasse was applied as fire-retardant filler to prepare the waterborne intumescent fireproof coating. The effect of bagasse on the properties of the fireproof coating was investigated by fire protection test, thermogravimetric (TG), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), water resistance test and mechanical properties test. The result demonstrated the coating contained 1.5wt.% bagasse performed best in fire protection, thermal stability, oxidation resistance. Moreover, the char layer was dense and continuous. However, the fireproof coating contained 2 wt.% bagasse had excellent performance in water resistance test and mechanical properties test due to its properties of fiber. In addition, the components and chemical structure of char layer were characterized to study the flame retardant mechanism of bagasse in the fireproof coating.

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

scholarly journals Experimental and Physico-Chemical Comparison of ZnO Nanoparticles’ Activity for Photocatalytic Applications in Wastewater Treatment

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 678
Author(s):  
Stefano Alberti ◽  
Irene Basciu ◽  
Marco Vocciante ◽  
Maurizio Ferretti
Keyword(s):  
Wastewater Treatment ◽  
Zno Nanoparticles ◽  
Energy Dispersive Spectrometer ◽  
Chemical Properties ◽  
X Ray Diffraction ◽  
Commercial Sample ◽  
Synthetic Process ◽  
Physico Chemical ◽  
Photocatalytic Applications ◽  
Reflectance Measurements

In this contribution, the photoactivity upon activation by simulated sunlight of zinc oxide (ZnO) obtained from two different synthetic pathways (Acetate and Nitrate) is investigated for water purification. Different reagents and processes were exploited to obtain ZnO nanoparticles. Products have been characterized by means of X-Ray Diffraction, Scanning Electron Microscopy along with Energy Dispersive Spectrometer, Dynamic Light Scattering, and Diffuse Reflectance Measurements, to highlight the different outcomes ascribable to each synthesis. A comparison of characteristics and performances was also carried out with respect to commercial ZnO. Nanoparticles of this semiconductor can be obtained as aggregates with different degrees of purity, porosity, and shape, and their physical-chemical properties have been addressed to the specific use in wastewater treatment, testing their effectiveness on the photocatalytic degradation of methylene blue (MB) as a model pollutant. Excluding the commercial sample, experimental results evidenced a better photocatalytic behavior for the ZnO Nitrate sample annealed at 500 °C, which was found to be pure and stable in water, suggesting that ZnO could be effectively exploited as a heterogeneous photocatalyst for the degradation of emerging pollutants in water, provided that thermal treatment is included in the synthetic process.

scholarly journals Optimization of Gypsum Composition Against Setting Time And Compressive Strength In Clinker For PCC (Portland Composite Cement)

2021 ◽  
Vol 1053 (1) ◽  
pp. 012116
Author(s):  
Herliati ◽  
Anggi Sagitha ◽  
A. Dyah Puspita ◽  
R. Puput Dwi ◽  
Akhirudin Salasa
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Composite Cement

scholarly journals Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Xin Zhang ◽  
Guanghui Li ◽  
Jinxiang You ◽  
Jian Wang ◽  
Jun Luo ◽  
...  
Keyword(s):  
Sodium Carbonate ◽  
Energy Dispersive Spectrometer ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Activation ◽  
X Ray ◽  
Shed Light ◽  
Soda Ash ◽  
Scanning Electron

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.

Sedimentary Clays as Geopolymer Precursor

2018 ◽  
Vol 39 ◽  
pp. 97-111
Author(s):  
F. Mostefa ◽  
Nasr Eddine Bouhamou ◽  
H.A. Mesbah ◽  
Salima Aggoun ◽  
D. Mekhatria
Keyword(s):  
Sodium Hydroxide ◽  
Mineralogical Composition ◽  
Cementitious Materials ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Calcination Time ◽  
Calorimetric Analysis ◽  
X Ray ◽  
Before And After ◽  
Mechanical Performances

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

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