scholarly journals Effect of Nanosilica on the Fresh Properties of Cement-Based Grouting Material in the Portland-Sulphoaluminate Composite System

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Shengli Li ◽  
Tingting Xu
Keyword(s):  
Particle Size ◽  
Apparent Density ◽  
Composite System ◽  
Setting Time ◽  
Xrd Analysis ◽  
Hydration Reaction ◽  
Particle Sizes ◽  
Fresh Properties ◽  
Air Content ◽  
Grouting Material

The effect of NS particle size and content on the fresh properties of the grouting material based on the portland-sulphoaluminate composite system was analyzed. The experimental results indicated that air content increased and apparent density decreased, with increased NS content, but the NS particle sizes have minimal effect on the air content and apparent density. The setting time of mortar was significantly shortened, with increased NS content; however, NS particle sizes had little influence on the setting time. The effect of fluidity on the mortars adding NS with particle size of 30 nm is larger than NS with particle sizes of 15 and 50 nm and the fluidity decreased with increased NS content, but the fluidity of mortars with the particle sizes of 15 and 50 nm is almost not affected by the NS content. XRD analysis shows that the formation of ettringite was promoted and the process of hydration reaction of cement was accelerated with the addition of NS. At the microscopic level, the interfacial transition zone (ITZ) of the grouting material became denser and the formation of C-S-H gel was promoted after adding NS.

scholarly journals One-Step Synthesis of Spherical γ-Fe2O3 Nanopowders and the Evaluation of Their Photocatalytic Activity for Orange I Degradation

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Chunhua Liang ◽  
Hui Liu ◽  
Jianmin Zhou ◽  
Xiaochun Peng ◽  
Haizhou Zhang
Keyword(s):  
Particle Size ◽  
Reaction Time ◽  
Synthesis Method ◽  
Total Pore Volume ◽  
Xrd Analysis ◽  
Bet Surface Area ◽  
Particle Sizes ◽  
Aqueous Synthesis ◽  
One Step ◽  
The One

Maghemite (γ-Fe2O3) nanopowders were synthesized under aeration (oxidizing) conditions by aqueous synthesis in this study. The microstructures of the prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-BJH. The XRD analysis and the chemical experiments showed that well-crystallized γ-Fe2O3 nanoparticles were successfully obtained with a mean particle size of approximately 17 nm. The prepared γ-Fe2O3 was spherical with a BET surface area of 14.357 m2/g and a total pore volume of 0.050 cm3/g. Varying the reaction conditions, such as pH, temperature, and reaction time, we obtained crystallized γ-Fe2O3 powders with different crystallization extent and different particle sizes. When the pH of the reaction suspension was increased, the reaction time was prolonged, and the reaction temperature was increased, the γ-Fe2O3 powders underwent superior crystallization and had larger particle sizes. All the obtained γ-Fe2O3 powders had significant photocatalytic activities under both UV and visible light irradiation for Orange I degradation, and the powders with better crystallization and larger particle size had relatively lower activities for Orange I photocatalytic degradation. The one-step aqueous synthesis method presented in this paper may provide an advantageous pathway to synthesize large quantities of this important iron oxide.

scholarly journals EFFECT OF PARTICLE SIZE OF GROSSMAN'S CEMENT POWDER ON SETTING TIME

1998 ◽  
Vol 12 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Jesus Djalma PÉCORA ◽  
Ricardo Gariba SILVA ◽  
Ricardo Novak SAVIOLI ◽  
Luis Pascoal VANSAN
Keyword(s):  
Particle Size ◽  
Powder Particle ◽  
Setting Time ◽  
Particle Sizes ◽  
Cement Powder ◽  
Effect Of Particle Size

A study was conducted on the hardening time of three Grossman's cements with different powder particle sizes (60, 100 and 150 mesh) using Specification n. 57 of the AMERICAN DENTAL ASSOCIATION1 (1983). The cement obtained from mesh 150 particles showed the longest hardening time (22 minutes), which was different when compared to mesh 60 (17 minutes) and 100 (17 minutes) particles.

scholarly journals Particle Size Dependence of TiO2Electrodes in Rechargeable Lithium Battery

1996 ◽  
Vol 19 (3) ◽  
pp. 189-198 ◽  
Author(s):  
S. Y. Huang ◽  
G. Campet ◽  
N. Treuil ◽  
J. Porter ◽  
K. Chhor
Keyword(s):  
Particle Size ◽  
Lithium Battery ◽  
Size Dependence ◽  
Storage Capacity ◽  
Xrd Analysis ◽  
Structural Defects ◽  
Particle Sizes ◽  
Nanosized Particles ◽  
Rechargeable Lithium Battery ◽  
Surface Areas

Particle size effects in five anatase TiO2pellet electrodes with different particle sizes (4 ∼ 300nm) and surface areas (8 ∼ 380m2/g) were studied by XRD analysis, chronopotentiometry and chronoamperometry in Li/LiN(CF3SO2)2+ EC:DME/TiO2cells. Nanosized TiO2electrodes showed by 22% larger storage capacity, 50% lower overvoltage loss at the same current density, and 75% higher charge density for a given time than microsized ones; electric storage capacity enhances more rapidly with decreasing particle size and increasing surface area in a nanoscale region than in a microscale region. The particle size dependence may be explained by surface morphology of electrodes and existence of structural defects or distortion in the surface layer of TiO2nanosized particles.

Investigations on Degradable and Figuline Calcium Alkaline Phosphate Cements with Multimodal Particle Size Distribution

2011 ◽  
Vol 493-494 ◽  
pp. 355-360
Author(s):  
F. Dombrowski ◽  
R. Hoffmann ◽  
Ute Ploska ◽  
Heidi Marx ◽  
Georg Berger
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Setting Time ◽  
Volume Ratio ◽  
Particle Sizes ◽  
Powder Mixtures ◽  
Setting Reaction ◽  
Tap Density

The paper presented here deals with rheological and hardening properties during the setting reaction, and density and compressive strength after the final setting of a figuline composite consisting of Ca2KNa(PO4)2and 2wt% medium gel strength gelatin. Compared to the composite with monomodal particle size distribution (d50=7.18µm; span=3.9) and its properties during and after setting reaction, the goal of this work is to increase the resulting product compressive strength by mixing different particle sizes in order to obtain bi- and trimodal distributions. For the bimodal powder mixtures the ratio in diameter (dcourse/dsmall) was chosen with 7/1 and volume ratio dcourse/dsmallwas 70/30%. For the trimodal powder mixtures the ratio in diameter (dcourse/dmedium/dsmall) was chosen with 70/7/1 and volume ratio dcourse/dmedium/dsmallwas set to 44/28/28%.After establishing an adequate crushing and sieving process the tap density and powder density of each fraction was determined. Subsequently, the different particle sizes were mixed and the densities and the Hausner ratio were determined again. The mixtures show an increase in both densities especially the tap density increased significantly. Rheological investigations show that the graphs of storage and loss moduli of the multimodal powder mixtures respectively are similar. The characteristic setting times show a slight decrease compared with the monomodal composite but not significantly different data. When comparing the resulting compressive strength of cylindrical samples, which were stored direct after reaching the initial setting time under physiological conditions, the studies illustrated in all cases for the multimodal mixtures a significant increase in compressive strength and a higher density.

Effects of Vibratory Disc Milling Time on the Physiochemical and Morphological Properties of Coal Fly Ash Nanoparticles

2019 ◽  
Vol 796 ◽  
pp. 38-45 ◽  
Author(s):  
Omolayo M. Ikumapayi ◽  
Esther Titilayo Akinlabi
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Milling Time ◽  
Coal Fly Ash ◽  
Xrd Analysis ◽  
Morphological Properties ◽  
Particle Sizes ◽  
Pore Size Distributions ◽  
Crystal Phases ◽  
Calcium Iron

In this study, the mechanical disc milling of coal fly ash (CFA) produced by ESKOM thermal station in South Africa has been investigated. The present work covers the effects of milling time on the characteristics such as crystal phases, particle sizes, morphology and physiology of the powder. The produced nanoparticle powders were characterized by SEM-EDX, XRD, and XRF. The milling time was carried out at (t=0, 20, 40, and 60 minutes) at a constant milling speed of 940 rpm. The results showed that mean area of the particles of the particle sizes increased from 75 µm size to approximately 200 nm which revealed that there was 62.5 % increase in the number of particle size as a result of the disintegration of the area of particle sizes. The crystal phases detected by the XRD in CFA are hexagonal, orthorhombic, rhombohedral and anorthic. XRD analysis showed that the most dominant minerals in coal fly ash are Quartz (SiO2), Mullite (Al2.32Si0.68O4.84), Sillimanite (Al2(SiO4)O, Calcite high (CaCO3), Hematite (Fe2O3), Microcline (KAlSi3O8). It was also revealed by EDX that the main elemental compositions present in CFA are silicon, aluminium, calcium, iron, titanium and magnesium. It was established in the study that the duration of the milling affects volume, surface area, particle size, pore size distributions, as well as the microstructure

Research and Evaluation of High Temperature Plugging Agent

2013 ◽  
Vol 750-752 ◽  
pp. 1685-1688
Author(s):  
Peng Fei Shen ◽  
Yong Sheng Chen ◽  
Ling Li ◽  
Yin Ni ◽  
Na Zhao ◽  
...  
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
High Temperature ◽  
Ultrafine Particles ◽  
High Performance ◽  
Setting Time ◽  
Initial Setting Time ◽  
Grouting Material ◽  
Initial Setting ◽  
Strength And Durability

Superfine cement is an ideal grouting material of high-performance ultrafine particles. It has excellent permeability, higher strength and durability. One of the most important features of superfine cement is no pollution on environment. SHD and SCC are two kinds of cement which have different performance. Comparing particle size, initial setting time, compressive strength and plug rate of two kinds of superfine cement by experiment. The result of experiment shows that cement SCC has higher compressive strength and plug rate at higher temperatures.

scholarly journals Improving the Mechanical Properties of Sulfoaluminate Cement-Based Grouting Material by Incorporating Limestone Powder for a Double Fluid System

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4854 ◽  
Author(s):  
Yanfeng Wang ◽  
Songhui Liu ◽  
Dongxing Xuan ◽  
Xuemao Guan ◽  
Haibo Zhang
Keyword(s):  
Compressive Strength ◽  
Reaction Rate ◽  
Setting Time ◽  
Limestone Powder ◽  
Hydration Reaction ◽  
Replacement Rate ◽  
Early Hydration ◽  
Nucleation Effect ◽  
Grouting Material ◽  
Late Stages

To improve the hardening performance of sulfoaluminate cement-based grouting material (SCGM) and reduce its cost, limestone powder was adopted to replace anhydrite in the control SCGM. The influence of the replacement rate of limestone powder on the hydration, hardening strength, expansion, and microstructure evolution of the SCGM was systematically researched. The results indicated that replacing anhydrite with limestone powder in SCGM can improve the flowability, shorten the setting time, and enhance the compressive strength at early and late stages. When the replacement rate of limestone powder was 20%, the compressive strength of SCGM for 6 h and 28 days increased by 146.41% and 22.33%, respectively. These enhancements were attributed to the fact that fine limestone powder can accelerate the early hydration reaction rate and promote the formation of ettringite due to its nucleation effect. Moreover, due to the presence of limestone powder, mono-carbonate (Mc) can be formed, which would densify the microstructure and refine the pore structure of the hardened SCGM.

Experimental investigation of pozzolanic concrete containing wheat straw ash

2019 ◽  
Vol 46 (10) ◽  
pp. 941-951
Author(s):  
Muhammad Riaz Ahmad ◽  
Muhammad Burhan Sharif ◽  
Hafiz Asad Ali ◽  
Munawar Hussain ◽  
Bing Chen
Keyword(s):  
Wheat Straw ◽  
Material Characterization ◽  
Setting Time ◽  
Xrd Analysis ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pozzolanic Material ◽  
Straw Ash

This study investigated the detailed optimization of wheat straw ash (WSA) as a pozzolanic material. Characterization of WSA as pozzolanic materials was carried out according to ASTM C618 and results indicated that WSA calcined at 700 °C for 2 h fulfilled ASTM C618 requirement and results were also confirmed by X-ray diffraction (XRD) analysis of WSA samples. Effect of WSA on setting time, mechanical properties, alkali–silica reaction (ASR), hydration process, and microstructure of cement paste (CP) and concrete was studied. Compressive and flexural strength of concrete mixture containing 14% WSA was 7.5% and 19.5% more as compared to control mixture at 28 days respectively. ASR expansion of mortar prisms and hydration temperature was reduced due to WSA incorporation. XRD and scanning electron microscopy investigations of CP indicated that WSA improved the microstructure of CP and was effective in imparting the pozzolanic characteristics during hydration reaction at 7 and 28 days.

scholarly journals Studies on the effect of coal particle size on biodepyritization of high sulfur coal in batch bioreactor

2015 ◽  
Vol 17 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Sradhanjali Singh ◽  
Haragobinda Srichandan ◽  
Ashish Pathak ◽  
Chandra Sekhar Gahan ◽  
Sujeong Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Large Scale ◽  
Xrd Analysis ◽  
Batch Reactors ◽  
Particle Sizes ◽  
Median Particle Size ◽  
Batch Bioreactor ◽  
Moderate Thermophiles ◽  
Median Particle ◽  
Loss Of Mass

Abstract The moderate thermophilic mix culture bacteria were used to depyritize the Illinois coal of varying particle sizes (-100 μm, 100-200 μm, +200 μm). Mineral libration analysis showed the presence of pyrite along with other minerals in coal. Microbial depyritization of coal was carried out in stirred tank batch reactors in presence of an iron-free 9K medium. The results indicate that microbial depyritization of coal using moderate thermophiles is an efficient process. Moreover, particle size of coal is an important parameter which affects the efficiency of microbial depyritization process. At the end of the experiment, a maximum of 75% pyrite and 66% of pyritic sulphur were removed from the median particle size. The XRD analysis showed the absence of pyrite mineral in the treated coal sample. A good mass balance was also obtained with net loss of mass ranging from 5-9% showing the feasibility of the process for large scale applications.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

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