scholarly journals Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 47 ◽  
Author(s):  
Yunbing Hou ◽  
Pengchu Ding ◽  
Dong Han ◽  
Xing Zhang ◽  
Shuxiong Cao
Keyword(s):  
Pore Size ◽  
Raw Material ◽  
Curing Time ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Hydration Properties ◽  
Crystalline Phases ◽  
X Ray ◽  
Mercury Intrusion ◽  
Furnace Slag

Blast furnace slag (BFS) is often used as a cement-based raw material for underground filling and surface cemented paste discharge of tailings during mining processes. This paper studied a new cement-based material (NCM) with BFS to replace ordinary Portland cement (OPC). A uniaxial compressive strength (UCS) experiment was used to test the mechanical strength of samples; X-ray diffraction and thermal gravity experiments were used to test the crystalline phases and amount of hydration products by samples; a scanning electron microscope experiment was used to observe the influence of the hydration products morphology by samples; mercury intrusion porosimetry experiment was used to analyze the pore size distribution of samples. The samples with NCM had an optimum UCS; the crystalline phases of the hydration products were similar in OPC and NCM. However, the amount of product formed in OPC was less than that in NCM at the same curing time; more ettringite and calcium silicate hydrate were produced in samples with NCM, which filled the pores and enhanced the UCS of the samples. The final mercury intrusion volume of the samples with NCM were lower than the samples with OPC at the same curing time, which showed that samples with NCM had lower porosities. For the samples with NCM and OPC cured from 7 days to 28 days, the mercury intrusion volume was reduced by 18% and 13%, and the most common pore size of the samples reduced by 53% and 29%, respectively. This showed after 21 days curing time, the pores of all the samples getting smaller; however, the samples with NCM were more compact. The main ingredients of the NCM were clinker, lime, gypsum and BFS, and its ratio was 14:6:10:70. The content of additives to NCM was 0.4%, and the ratio of sodium sulfate: alum: sodium fluorosilicate was 2:1:1.

scholarly journals The Effects of Temperature on the Hydrothermal Synthesis of Hydroxyapatite-Zeolite Using Blast Furnace Slag

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2131 ◽  
Author(s):  
G.U. Ryu ◽  
G.M. Kim ◽  
Hammad R. Khalid ◽  
H.K. Lee
Keyword(s):  
Blast Furnace ◽  
Hydrothermal Synthesis ◽  
Blast Furnace Slag ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Type Zeolite ◽  
Effects Of Temperature ◽  
Furnace Slag

Blast furnace slag, an industrial by-product, is emerging as a potential raw material to synthesize hydroxyapatite and zeolite. In this study, the effects of temperature on the hydrothermal synthesis of hydroxyapatite-zeolite from blast furnace slag were investigated. Specimens were synthesized at different temperatures (room temperature, 50, 90, 120, or 150 °C). The synthesized specimens were analyzed qualitatively and quantitatively via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), BET/BJH, and scanning electron microscopy/energy dispersive using X-ray analysis (SEM/EDX). It was found that the hydroxyapatite phase was synthesized at all the reaction temperatures, while faujasite type zeolite appeared in the specimens synthesized at 90 and 120 °C. Moreover, faujasite was replaced by hydroxysodalite in the specimens synthesized at 150 °C. Additionally, the crystals of the hydroxyapatite tended to become larger and total crystallinity increased as the reaction temperature increased.

scholarly journals Preparation of MgO-Templated N-Doped Mesoporous Carbons from Polyvinylpyrrolidone: Effect of Heating Temperature on Pore Size Distribution

2019 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Tomoya Takada ◽  
Mayu Kurihara
Keyword(s):  
Pore Size ◽  
Nitrogen Content ◽  
Acid Treatment ◽  
Heating Temperature ◽  
Inert Atmosphere ◽  
Raw Material ◽  
Mesoporous Carbons ◽  
X Ray Diffraction ◽  
X Ray ◽  
Templated Carbon

Magnesium oxide (MgO)-templated nitrogen (N)-doped mesoporous carbons were prepared by using polyvinylpyrrolidone (PVP) as a raw material and magnesium lactate (Mglac) as a precursor for the MgO template to examine the influence of heating temperature and MgO precursor (magnesium acetate was used in similar previous studies) on the pore size and nitrogen content. The MgO-templated carbon was obtained by heating the PVP/Mglac mixture in an inert atmosphere followed by an acid treatment for MgO removal. The mesopore size of the carbons was approximately 4 nm regardless of heating temperature, corresponding to the crystallite size of the MgO template estimated via X-ray diffraction. This indicates that the mesopore of approximately 4 nm was generated using the MgO template. However, larger pores were also found to exist. This result indicates that the larger pores generated through processes other than the MgO templating, likely the thermal decomposition of PVP, are contained in the templated carbon. The volume of the larger pores and the specific surface area increased with increasing heating temperature. The nitrogen content of the carbon decreased as the heating temperature was increased, but it was found to be irrelevant to the MgO precursor.

scholarly journals Crystallization and Quantification of Crystalline and Non-Crystalline Phases in Kaolin-Based Cordierites

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3104 ◽  
Author(s):  
Marta Valášková ◽  
Zdeněk Klika ◽  
Boris Novosad ◽  
Bedřich Smetana
Keyword(s):  
Raw Material ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray ◽  
Mineral Phases ◽  
Chemical Variability ◽  
Bulk Chemical ◽  
Size Variability ◽  
Cordierite Ceramics ◽  
Cordierite Structure

Kaolin is most often used as traditional raw material in ceramic industry. The purpose of the study was to obtain understanding of the structural and chemical variability of cordierite ceramics influenced by chemical and mineralogical properties of six raw kaolins taken from different localities when they are applied in ceramics mixtures with vermiculite and sintered up to 1300 °C. The X-ray diffraction and simultaneous thermogravimetric and differential thermal analysis were used to identify and characterize crystalline mineral phases and the course of reactions during the heating. The percentages of the crystalline and non-crystalline phases were newly determined by recalculation of the bulk chemical analyses of kaolins and cordierite ceramics using Chemical Quantitative Mineral Analysis (CQMA) method. Varying amounts of minerals in kaolins: kaolinite from 73.3 to 85.0, muscovite from 4.2 to 9.9, and quartz from 6.0 to 19.5 (mass %) affected amount of cordierite/indialite from 75.2 to 85.1, enstatite from 5.8 to 8.9 (when are calculated as their maximal possible percentages), and non-crystalline phases from 8.8 to 15.1 (mass %) in cordierite ceramics. Regression analysis predicted high relationship between quantity of: (a) kaolinite in kaolins and crystalline cordierite and (b) quartz in kaolins and non-crystalline phases in the ceramics. The migration of potassium from muscovite into the cordierite structure, melting point and crystallization of cordierite/indialite phases and pore size variability in relation to impurity of kaolins are documented and discussed.

Effect of Metakaolin Sand on Properties of Cement Composites

2014 ◽  
Vol 897 ◽  
pp. 176-179
Author(s):  
Ľudovít Krajči ◽  
Ivan Janotka ◽  
Marta Kuliffayova ◽  
Peter Uhlik
Keyword(s):  
Portland Cement ◽  
Mercury Intrusion Porosimetry ◽  
Structure Refinement ◽  
Hydrate Formation ◽  
Raw Material ◽  
Cement Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mercury Intrusion ◽  
Positive Effect

The Slovak natural raw material kaolin sand containing 36 wt.% of kaolinite from Vyšný Petrovec deposit was thermally transformed at 650 °C for 1 hour to the metakaolin sand with relevant content of metakaolinite. Behaviour of cement composites having replacement of Portland cement with metakaolin sand including 0; 5; 10 and 15 wt.% of metakaolinite and water to solids ratio of 0.5 cured in water for 28 days and 90 days was studied by thermal analysis, X-ray diffraction analysis and mercury intrusion porosimetry analysis. The study concerned calciumsilica hydrate and calcium aluminate hydrate formation, portlandite dehydroxylation and calcite decarbonation. The influence of curing time and metakaolinite content were estimated. The replacement of Portland cement by metakaolin sand led to positive effect on relevant compressive strengths. The changes in microstructure involved especially reduction in portlandite content and pore structure refinement.

Utilization of CFB Fly Ash in Eco-Cement: Mechanical Properties and Microstructural Analysis

2010 ◽  
Vol 150-151 ◽  
pp. 885-889 ◽  
Author(s):  
Xiao Ming Liu ◽  
Yu Li ◽  
Ling Ling Zhang ◽  
Da Qing Cang
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Circulating Fluidized Bed ◽  
Microstructural Analysis ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Xrd Techniques ◽  
Furnace Slag

The disposal of circulating fluidized bed (CFB) fly ash has been a serious environmental problem in the development of our society. In this work, the feasibility of recycling CFB fly ash as a blended material incorporating blast furnace slag (BFS), clinker and gypsum for the preparation of Eco-cement has been investigated. The mechanical properties of CFB fly ash based Eco-cements, including CFB fly ash–clinker system, CFB fly ash–ground BFS system, and CFB fly ash–ground BFS–clinker system, were evaluated in this paper. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used to analyze the microstructural changes and the hydration products of the CFB fly ash based Eco-cement pastes. The results indicated that it is feasible to use CFB fly ash along with BFS and clinker to produce Eco-cement. The hydration products of CFB fly ash based Eco-cement are mostly ettringite and amorphous C-S-H gel, which are principally responsible for the strength and structure development of CFB fly ash based Eco-cement in the hydration process.

The Study of Alkaline-Activated Magnesium Slag Cementitious Material

2012 ◽  
Vol 517 ◽  
pp. 363-366 ◽  
Author(s):  
Li Guang Xiao ◽  
Feng Luo ◽  
Rui Bo Li ◽  
Chang Yu Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Property ◽  
Interaction Mechanism ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Furnace Slag ◽  
Scanning Electron

Magnesium slag cementitious material was prepared successfully using the magnesium slag-furnace slag-clinker system and different activators in this paper. The effect of activator on the mechanical property of the material was studied. The hydration and microstructure of this composite cement were analyzed by X-ray diffraction and scanning electron microscopy and the interaction mechanism was researched. The results show that the activity of magnesium slag was enhanced significantly by adding a small amount of activator. Combined activators have the best effect. The hydration products of magnesium slag cementitious materials mortar were C-S-H, Aft and Ca (OH)2 and so on.

scholarly journals Influences of Ultrafine Slag Slurry Prepared by Wet Ball Milling on the Properties of Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Yubo Li ◽  
Shaobin Dai ◽  
Xingyang He ◽  
Ying Su
Keyword(s):  
Environmental Sustainability ◽  
Blast Furnace Slag ◽  
Ball Mill ◽  
High Performance ◽  
Mercury Intrusion Porosimetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mercury Intrusion ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

The application of ultrafine ground-granulated blast-furnace slag (GGBFS) in concrete becomes widely used for high performance and environmental sustainability. The form of ultrafine slag (UFS) used in concrete is powder for convenience of transport and store. Drying-grinding-drying processes are needed before the application for wet emission. This paper aims at exploring the performances of concrete blended with GGBFS in form of slurry. The ultrafine slag slurry (UFSS) was obtained by the process of grinding the original slag in a wet ball mill, which was mixed in concrete directly. The durations of grinding were 20 min, 40 min, and 60 min which were used to replace Portland cement with different percentages, namely, 20, 35, and 50, and were designed to compare cement with original slag concrete. The workability was investigated in terms of fluidity. Microstructure and pore structure were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The fluidity of concrete mixed with UFSS is deteriorated slightly. The microstructure and early strength were obviously improved with the grind duration extended.

Effect of Curing Time on the Pore Structure of the Portland Cement Concrete

2010 ◽  
Vol 44-47 ◽  
pp. 2592-2596
Author(s):  
Wei Lun Wang ◽  
Peng Liu
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Pore Structure ◽  
Mercury Intrusion Porosimetry ◽  
Curing Time ◽  
Hydration Products ◽  
Portland Cement Concrete ◽  
X Ray Diffraction ◽  
Cement Concrete ◽  
X Ray

In this paper, the influence of curing time on the compressive strength and pore structure of the Portland cement concrete was investigated. The phase composition and morphology of hydration products of Portland cement were analyzed with X-ray diffraction (XRD). In addition, the porosity and pore distribution of the concrete were also researched using mercury intrusion porosimetry (MIP), surface area and porosity analyzer (BET). The results show that the influence of curing time on the compressive strength and pore structure of the concrete is obvious. With curing time increasing, the compressive strength of the concrete increased and the porosity decreased. The corresponding fractal dimension of the pore and the microstructure were changed, as well. With time increasing, more hydration products were produced.

Study for Control of Dimensional Distortion in Tempered Industrial Parts

2020 ◽  
Author(s):  
João Alfredo Scheidemantel ◽  
Christian Doré ◽  
Lucile Cecília Peruzzo
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Manufacturing Process ◽  
Raw Material ◽  
Machining Process ◽  
Material Surface ◽  
Yield Limit ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray

Abstract The presence of residual stress generated in the manufacturing process defines one of the biggest problems found in the mechanical metal industry. In the search of mechanical properties to a specific application, it is mandatory to impose the parts at very critical mechanical, chemical or thermal requests. The study analyzes all the steps that apply considerable stresses to the component during the manufacturing process and, therefore, discover which ones add more stresses to the yield limit of the material. It was also intended to contribute with relevant information regarding the surface integrity of the material, with bigger coverage in the residual stresses generated where, due to their nature and expressiveness, they can be beneficial or harmful to the component’s useful life. Accordingly, the objective was to analyze the raw material of SAE 4140 steel through its microstructure and verification of its chemical and mechanical characterization. In order to reduce the occurrence of dimensional distortions in excess of tolerance, we sought to identify the most critical step and, therefore, act with viable possibilities and without relevant costs for the prevention of the problem encountered. In order to measure its stress and define the process in which the highest inclusion of residual tractive stresses is characterized, these being the deleterious ones for the process and for the product, we used the method of measuring residual stresses by ray diffraction in X. In your measurement, the stresses included on the surface of the specimens were measured at specific stages of the process. X-ray diffraction analysis analyzes the diffraction planes and their respective interplanar distances from a specific material, as well as the densities of atoms along the crystalline planes. Using mathematical models, it is possible to measure the residual stress existing in the investigated parts. In view of the analysis by X-ray diffraction, it was verified the existence of disordered variations and modifications of the crystalline phases on the material surface, at the end of the finish machining process. These crystalline phases which, together with a less aggressive fabrication, favor plastic deformation due to the presence of residual stresses which surpass those of the yield limit of the analyzed material. In this sense, it was possible to determine which the most critical operation related to the component request is the machining in which it is applied. Since the subsequent processes only aggravates this condition, resulting in an unusable component for the proposed application without adding a higher cost to the product, either through the use of some rework or scrap procedure.

scholarly journals Changes in mineralogy and microstructure of a lime-treated silty soil during curing time

2020 ◽  
Vol 195 ◽  
pp. 03044
Author(s):  
Zi YING ◽  
Yu-jun Cui ◽  
Nadia Benahmed ◽  
Myriam Duc
Keyword(s):  
Mercury Intrusion Porosimetry ◽  
Soil Samples ◽  
Time Effect ◽  
Curing Time ◽  
X Ray Diffraction ◽  
Lime Treatment ◽  
Treated Soil ◽  
X Ray ◽  
Mercury Intrusion

Lime treatment is widely applied to improve the workability and long-term durability of soils. In this study, the curing time effect on the mineralogy and microstructure of lime-treated soil was investigated. The soil samples were prepared with 2 % lime and statically compacted at dry (w = 17 %) and wet (w = 20%) sides of optimum. X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) were performed on lime-treated soil at various curing times. The presence of XRD peaks attributed to portlandite even after 150 days curing time indicated that it was not totally converted in cementitious compounds after reaction with silica and alumina from clay minerals. By contrast, no obvious XRD reflections of well-crystallized cementitious compounds were identified. Furthermore, all samples compacted at dry and wet side of optimum exhibited bi-modal pore size distribution, with a decrease of macro-pore frequency with increasing water content. The microstructure changes with increasing curing time did not follow monotonic tendency. On the whole, the quantities of pores less than 0.006 μm and micro-pores increased and the quantity of macro-pores decreased with increasing curing time due to the possible creation of poorly crystallized or amorphous cementitious compounds.

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