The Effect of Composition and Fineness of Mineral Fillers on Structure of Asphalt Binder

2021 ◽  
Vol 1017 ◽  
pp. 81-90
Author(s):  
Mikhail S. Lebedev ◽  
Marina I. Kozhukhova ◽  
Evgeniy A. Yakovlev
Keyword(s):  
Structure Formation ◽  
Surface Area ◽  
Water Saturation ◽  
Chemical Reactivity ◽  
Asphalt Binder ◽  
Sem Analysis ◽  
Void Content ◽  
The Matrix ◽  
Mineral Fillers ◽  
Compaction Degree

Ultra-fine filler or mineral powder is the main mineral component responsible for structure formation in the bitumen-mineral system, therefore mineral and chemical composition, chemical reactivity, surface area, fineness, particle shape, porosity and density are the crucial parameters for structure formation of the composite. This work studied the effect of fineness and chemical and mineral composition of fillers on the structure of asphalt binder. It was demonstrated that an increase in surface area boosts porosity, and void content of the filler, but reduces the porous size. For carbonate fillers such as limestone and chalk with high fineness it was investigated that compaction applied to asphalt binder specimens showed very low water saturation. This can be explained by the film effect of water impermeable bitumen in the matrix and by small porous size with mostly close pores. An increase in surface area of silicate fillers improves the compaction of structure but cannot reach the same level of compaction degree demonstrated by the specimens with carbonate fillers. SEM analysis of microstructural characteristics for the asphalt binder showed that the incorporation of fine-fractioned chalk filler resulted in the formation of asphalt binder with high density and micro-and nanoporous matrix.

Investigation of Thermochemical Hydrogen Production via the Novel Thermo-Mechanical Stabilized Iron Oxide-Zirconia Porous Structure

2013 ◽  
Author(s):  
Ayyoub M. Mehdizadeh ◽  
Kelvin Randhir ◽  
James F. Klausner ◽  
Nicholas AuYeung ◽  
Fotouh Al-Raqom ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Porous Structure ◽  
Chemical Reactivity ◽  
Thermal Reduction ◽  
The Novel ◽  
Concentrated Solar Energy ◽  
The Matrix ◽  
Unique Method ◽  
Laboratory Scale Reactor ◽  
The Stability

In this study we have developed a unique method for synthesizing very reactive water splitting materials that will remain stable at temperatures as high as 1450 °C to efficiently produce clean hydrogen from concentrated solar energy. The hydrogen production for a laboratory scale reactor using a “Thermo-mechanical Stabilized Porous Structure” (TSPS) is experimentally investigated for oxidation and thermal reduction temperatures of 1200 and 1450 °C, respectively. The stability and reactivity of a 10 g TSPS over many consecutive oxidation and thermal reduction cycles for different particle size ranges has been investigated. The novel thermo-mechanical stabilization exploits sintering and controls the geometry of the matrix of particles inside the structure in a favorable manner so that the chemical reactivity of the structure remains intact. The experimental results demonstrate that this structure yields peak hydrogen production rates of 1–2 cm3/(min.gFe3O4) during the oxidation step at 1200 °C and the 30 minute thermal reduction step at 1450 ° C without noticeable degradation over many consecutive cycles. The hydrogen production rate is one of the highest yet reported in the open literature for thermochemical looping processes using thermal reduction. This novel process has strong potential for developing an enabling technology for efficient and commercially viable solar fuel production.

scholarly journals Particularities of structure formation of aluminum-copper composite materials manufactured by casting technology

2020 ◽  
pp. 116-121
Author(s):  
V. A. Kalinichenko ◽  
A. S. Kalinichenko ◽  
S. V. Grigoriev
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Structure Formation ◽  
Matrix Material ◽  
Matrix Alloy ◽  
Alloying Elements ◽  
Casting Technology ◽  
The Matrix ◽  
Reinforcing Material ◽  
Copper Composite

To create friction pairs operating in severe working conditions, composite materials are now increasingly used. Composite materials obtained with the use of casting technologies are of interest due to the possibility to manufacture wide range of compositions at low price compared to powder metallurgy. Despite the fact that many composite materials have been sufficiently studied, it is of interest to develop new areas of application and give them the properties required by the consumer. In the present work the composite materials on the basis of silumin reinforced with copper granules were considered. Attention was paid to the interaction between the matrix alloy and the reinforcing phase material as determining the properties of the composite material. The analysis of distribution of the basic alloying elements in volume of composite material and also in zones of the interphases interaction is carried out. The analysis of the possibility of obtaining a strong interphase zone of contact between the reinforcing component and the matrix material without significant dissolution of the reinforcing material is carried out.

Experimental Investigation on Volume Fraction of Mechanical and Physical Properties of Flax and Bamboo Fibers Reinforced Hybrid Epoxy Composites

2017 ◽  
Vol 25 (3) ◽  
pp. 229-236 ◽  
Author(s):  
S. Sathish ◽  
K. Kumaresan ◽  
L. Prabhu ◽  
N. Vigneshkumar
Keyword(s):  
Physical Properties ◽  
Epoxy Resin ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Sem Analysis ◽  
Epoxy Composites ◽  
Resin Matrix ◽  
Void Content ◽  
Mechanical And Physical Properties ◽  
Bamboo Fibers

The aim of this paper is to study the effect of volume fraction on mechanical and physical properties such as tensile, flexural, impact, interlaminar shear strength, void content and water absorption of flax and bamboo fibers reinforced hybrid epoxy composites. Flax and bamboo fibers reinforced epoxy resin matrix hybrid composites have been fabricated by compression molding techniques. The hybrid composites were fabricated with different volume fraction of fibers. SEM analysis on the hybrid composite materials was performed to analyze the bonding behavior of materials and internal structure of the fractured surfaces. The effect of chemical treatment of flax and bamboo fibers was verified by FTIR analysis. The results showed that the tensile, impact, flexural and ILSS are maximum for 40:0 (flax: bamboo) hybrid composites. The void content decreased for 20:20 (flax:bamboo) composites due to tightly packed flax fiber and more compatibility towards epoxy resin.

Initial aggregate formation: Disentangling the effects of soil texture, OM properties and microbial community using artificial model soils

2021 ◽  
Author(s):  
Franziska B. Bucka ◽  
Vincent J.M.N.L. Felde ◽  
Stephan Peth ◽  
Ingrid Kögel-Knabner
Keyword(s):  
Microbial Community ◽  
Specific Surface ◽  
Structure Formation ◽  
Surface Area ◽  
Specific Surface Area ◽  
Soil Structure ◽  
Mechanical Stability ◽  
Aggregate Formation ◽  
Water Stable Aggregates ◽  
Mineral Particles

<p>The interaction between mineral particles and organic matter (OM) is an important and complex process in the course of soil structure formation. For a better understanding it is necessary to disentangle the texture-dependent interplay of individual OM types and mineral particles. We developed an experimental set-up to study early aggregate formation within a controlled lab environment. Artificial soil microcosms with a mineral mixture resembling arable soils of three different textures (clay loam, loam and sandy loam) were used in a short-term, 30-day incubation experiment under constant water-tension. OM was added individually either as plant litter (POM) of two different sizes (0.63-2 mm and < 63 µm, respectively) or bacterial necromass (Bacillus subtilis). The mechanisms of soil structure formation were investigated by isolating water-stable aggregates after the incubation, analyzing their mechanical stability and organic carbon allocation, and measuring the specific surface area and OM covers of the mineral surface, microbial activity, and community structure.</p><p>The dry mixing process and incubation of the mineral mixtures led to particle-particle interactions and fine particle coatings of the sand grains as shown by a reduction of the specific surface area. The OM input of all types caused between 3 to 17% of the mineral surfaces to be covered by OM, with larger covered areas in the clay-rich mixtures. The added OM was quickly accessed and degraded by microbes, as shown by the peak in CO<sub>2</sub>-release within the first 10 days of the incubation. The POM of both sizes induced the predominant formation of water-stable macroaggregates (0.63-30 mm) with a mass contribution of 72 to 91% (irrespective of texture) and fostered the development of a microbial community with a high relative abundance of fungi. The bacterial necromass induced the formation of macroaggregates, but also microaggregates (63-200 µm), while the microbial community was dominated by bacteria. The mechanical stability analysis showed that very small forces < 4 N were sufficient for aggregate failure and breakdown to 80% of the original aggregate size.</p><p>We propose that the microbial degradation of all OM types leads to small, distinct OM clusters consisting of OM substrate, microbes, and extracellular polymeric substances. These interact with mineral particles, resulting in the cross-linking of particles and formation of water-stable aggregates in all textures. The OM can thereby act both as microbial substrate and as structural building block. The initially formed aggregates are a loosely connected scaffold with a very low mechanical stability. Differences in the developed microbial community may lead to additional stabilization mechanisms, like fungal hyphae enmeshing and stabilizing larger aggregates also in sandy texture.</p>

SYNTHESIS AND CHARACTERIZATION OF NEEM-BASED ZINC OXIDE PHOTOCATALYST

2021 ◽  
Vol 36 (1) ◽  
pp. 9-15
Author(s):  
I.N Gana ◽  
V.U Ohageria ◽  
U.G Akpan ◽  
I.J Ani
Keyword(s):  
Zinc Oxide ◽  
Green Synthesis ◽  
Surface Area ◽  
Leaf Extract ◽  
Zinc Acetate Dihydrate ◽  
Sol Gel ◽  
Sem Analysis ◽  
X Ray ◽  
Bet Analysis ◽  
Neem Leaf Extract

The use of chemicals for the synthesis of photocatalyts poses threat to the environment. In this study, an active photocatalyst, Dalbejiya Dongoyaro (Azadirachta indica)-based zinc oxide (ZnO) was biosynthesized from zinc acetate dihydrate using sol gel and precipitation methods. The synthesized samples were characterized using Fourier Transfer InfraRed (FTIR), X-Ray Diffractometry (XRD), Brunauer Emmet Teller (BET), Energy Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) characterization techniques. The XRD and SEM analysis of the green synthesized and non-green synthesized ZnO demonstrated the formation of hexagonal wurtzite crystalline structure and agglomerated morphology. EDX analysis demonstrated the existence of Zn and O as the major constituents of the as-synthesized nanoparticles with traces of carbon which could be attributed to the carbon tape of the sample holder. The BET analysis displayed that the surface area of the ZnO nanoparticles increased from 23.75 to 97.08 cm3/g after the green synthesis. Based on the surface area values, it can be derived that neem leaf extract enhanced the surface area of the green synthesized sample. Green synthesis is a promising route for the synthesis of photocatalyst nanoparticle which is environmentally friendly and sustainable method. Keywords: Zinc oxide, Neem leaf extract, Photocatalyt, Degradation, Bio-synthesis

Investigation into the hygrothermal behavior of fired clay materials during the freezing of supercooled water using experiments and numerical simulations

2021 ◽  
pp. 174425912110411
Author(s):  
Kazuma Fukui ◽  
Chiemi Iba ◽  
Madoka Taniguchi ◽  
Kouichi Takahashi ◽  
Daisuke Ogura
Keyword(s):  
Surface Area ◽  
Water Saturation ◽  
Supercooled Water ◽  
Clay Material ◽  
Experimental Conditions ◽  
Cooling Rates ◽  
Freezing Points ◽  
Hygrothermal Behavior ◽  
Short Period ◽  
Clay Materials

In this study, supercooling effects on the hygrothermal behavior of fired clay materials under various experimental conditions, such as water content, cooling rates, and size of specimens were investigated using experimental methods and hygrothermal simulations. We report results of the differential scanning calorimetry (DSC) and temperature distribution changes during a freeze–thaw (FT) experiment using unsaturated specimens. Also, we developed a numerical model of the freezing and thawing processes including the supercooling processes. The DSC results show the freezing of the supercooled water in a fired clay material is considerably faster than that in cement-based materials. It was also found that the dependency of the supercooling effects on the cooling rates seemed to be small. When the water saturation of a material decreases, the rate of the ice saturation increase during the freezing of the supercooled water is decreased while the freezing points of the supercooled water was not changed considerably. The comparison of the results of the FT experiment and hygrothermal simulations show that the combination of the existed hygrothermal model and a modified kinetic equation can reproduce the rapid temperature rise during the freezing of the supercooling water in the FT experiment. Finally, the size effects of specimens on the supercooling phenomenon was discussed based on the experimental and calculation results. The freezing points got higher when a specimen was larger. Due to differences in the ratio of the surface area to the volume, hygrothermal behavior in small specimens and relatively large specimens like that of the DSC and the FT experiment, respectively were markedly different. Water in a relatively large specimen with a small ratio of surface area to volume can achieve the thermodynamic equilibrium in a short period after the freezing starts.

scholarly journals Extraction of void fraction in metal matrix composite using morphological image processing

1994 ◽  
Vol 3 (2) ◽  
pp. 096369359400300
Author(s):  
Lun X. He ◽  
David K. Hsu ◽  
John P. Basart
Keyword(s):  
Image Processing ◽  
Void Fraction ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Matrix Material ◽  
Void Content ◽  
Matrix Composites ◽  
Cross Sectional ◽  
Morphological Image Processing ◽  
The Matrix

In continuous fiber reinforced metal matrix composites, the volume fraction of voids in the matrix material is an important parameter for material property characterization. In analyzing a cross-sectional micrograph of such a composite, the presence of fiber images and voids occurring on the perimeter of fibers complicates the determination of void content. This paper describes image processing steps using mathematical morphology for the extraction of void fraction in a composite.

scholarly journals Mathematical model of methane driven by hydraulic fracturing in gassy coal seams

2020 ◽  
Vol 38 (3-4) ◽  
pp. 127-147
Author(s):  
Weiyong Lu ◽  
Bingxiang Huang
Keyword(s):  
Mathematical Model ◽  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Hydraulic Fracture ◽  
Water Saturation ◽  
Reduction Rate ◽  
Space Time ◽  
Matrix Block ◽  
The Matrix ◽  
Pore Pressure Gradient

During hydraulic fracturing in gassy coal, methane is driven by hydraulic fracturing. However, its mathematical model has not been established yet. Based on the theory of ‘dual-porosity and dual-permeability’ fluid seepage, a mathematical model is established, with the cleat structure, main hydraulic fracture and methane driven by hydraulic fracturing considered simultaneously. With the help of the COMSOL Multiphysics software, the numerical solution of the mathematical model is obtained. In addition, the space–time rules of water and methane saturation, pore pressure and its gradient are obtained. It is concluded that (1) along the direction of the methane driven by hydraulic fracturing, the pore pressure at the cleat demonstrates a trend of first decreasing and later increasing. The pore pressure gradient exhibits certain regional characteristics along the direction of the methane driven by hydraulic fracturing. (2) Along the direction of the methane driven by hydraulic fracturing, the water saturation exhibits a decreasing trend; however, near the cleat or hydraulic fracture, the water saturation first increases and later decreases. The water saturation in the central region of the coal matrix block is smaller than that of its surrounding region, while the saturation of water in the entire matrix block is greater than that in the cleat or hydraulic fracture surrounding the matrix block. The water saturation at the same space point increases gradually with the time progression. The space–time distribution rules of methane saturation are contrary to those of the water saturation. (3) The free methane driven by hydraulic fracturing includes the original free methane and the free methane desorbed from the adsorption methane. The reduction rate of the adsorption methane is larger than that of free methane.

scholarly journals An Empirical Parameterization of Heterogeneous Ice Nucleation for Multiple Chemical Species of Aerosol

2008 ◽  
Vol 65 (9) ◽  
pp. 2757-2783 ◽  
Author(s):  
Vaughan T. J. Phillips ◽  
Paul J. DeMott ◽  
Constantin Andronache
Keyword(s):  
Surface Area ◽  
Heterogeneous Nucleation ◽  
Large Scale ◽  
Water Saturation ◽  
Chemical Species ◽  
Spectral Width ◽  
Diffusion Chamber ◽  
Field Studies ◽  
Cloud Models ◽  
Multiple Species

Abstract A novel, flexible framework is proposed for parameterizing the heterogeneous nucleation of ice within clouds. It has empirically derived dependencies on the chemistry and surface area of multiple species of ice nucleus (IN) aerosols. Effects from variability in mean size, spectral width, and mass loading of aerosols are represented via their influences on surface area. The parameterization is intended for application in large-scale atmospheric and cloud models that can predict 1) the supersaturation of water vapor, which requires a representation of vertical velocity on the cloud scale, and 2) concentrations of a variety of insoluble aerosol species. Observational data constraining the parameterization are principally from coincident field studies of IN activity and insoluble aerosol in the troposphere. The continuous flow diffusion chamber (CFDC) was deployed. Aerosol species are grouped by the parameterization into three basic types: dust and metallic compounds, inorganic black carbon, and insoluble organic aerosols. Further field observations inform the partitioning of measured IN concentrations among these basic groups of aerosol. The scarcity of heterogeneous nucleation, observed at humidities well below water saturation for warm subzero temperatures, is represented. Conventional and inside-out contact nucleation by IN is treated with a constant shift of their freezing temperatures. The empirical parameterization is described and compared with available field and laboratory observations and other schemes. Alternative schemes differ by up to five orders of magnitude in their freezing fractions (−30°C). New knowledge from future observational advances may be easily assimilated into the scheme’s framework. The essence of this versatile framework is the use of data concerning atmospheric IN sampled directly from the troposphere.

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