Scanning Electron Microscopy Image Analysis Research Articles

Sustainable development of recycled concrete aggregate through optimized acid-mechanical treatment: A simplified approach

Present research develops an optimized acid-mechanical treatment for recycled concrete aggregate (RCA). RCA prepared in the laboratory jaw crusher is further soaked for 24 h in a mild acetic acid solution. Acid-soaked recycled aggregates (SR) are mechanically treated at a series of charges and drum revolutions using Los Angeles machines. A performance-based quality identification approach is used to compare acid-mechanically treated recycled concrete aggregates (SRij). The VIKOR indices (QI) for each SRij is calculated by applying a multi-criteria decision-making approach. Based on performance, three SRij with the lowest QI are selected for an experimental study. The present research achieves 71.27 MPa compressive strength for concrete composed of a SRij with the lowest QI. This strength is around 16.06% higher than concrete composed of parent aggregate. Flexural strength, split tensile strength, fracture energy, ultrasonic pulse velocity (UPV) values, rapid-chloride penetration test (RCPT) values, water absorption, and abrasion resistance are in the range of what is expected for parent aggregate concrete. The scanning electron microscope (SEM) image analysis shows that the well compacted and uniform surface morphology of aggregate strengthens the newly developed interfacial transition zone (NITZ) and old interfacial transition zone (OITZ). Acid treatment reduces microcrack lengths and widths and mechanical treatment reduces microcracks and pores by reducing adherent mortar optimally. X-ray diffraction (XRD) analysis shows the lower calcium hydroxide (CH) content in the mortar attached to the SR. A reduced CH content lowers the porosity in the adhered mortar. Thus, improved quality of attached mortar and its reduced porosity strengthen the old interfacial transition zone (OITZ) and lowers the sorptivity of the concrete than reported and almost equal to that of parent aggregate concrete.

Microstructure Analysis of Cold Bituminous Emulsion Mixture Using Different Filler Type

Abstract In today’s scenario, the environmental impact of the transport sector plays a major role in net carbon emission generation and global warming. Seeing the emerging environmental issue, it has been mandatory to adopt sustainable technologies in every sector. The use of bitumen emulsion in the construction of pavement has been rapidly enhanced in the last decade. This technology eliminates the heating of aggregate and binder, resulting in a reduction of greenhouse gas emissions and energy consumption, which is also termed as cold mix technology. Filler has a major role in the formation of bonds between bitumen emulsion and aggregate. In the present study, cement, lime, and fly ash have been considered as filler materials along with stone dust and the required optimum emulsion content and water content were determined. The impact of filler on the breaking of bitumen emulsion is studied through scanning electron microscope image analysis. The impact of filler on pH of bitumen emulsion mastic is also evaluated. The optimum emulsion content in cold bituminous emulsion mixtures (CBEMs) depends on the particle size of the filler. The required water content for lime is less compared to other filler materials. The results show that cement and fly ash are pozzolanic in nature, form hydration products in the presence of water in CBEM, and result in higher density and stability. The study depicts the role of filler material in CBEM at the microlevel.

Fiber Orientation Quantification for Large Area Additively Manufactured Parts Using SEM Imaging.

Polymer-based additively manufactured parts are increasing in popularity for industrial applications due to their ease of manufacturing and design form freedom, but their structural and thermal performances are often limited to those of the base polymer system. These limitations can be mitigated by the addition of carbon fiber reinforcements to the polymer matrix, which enhances both the structural performance and the dimensional stability during cooling. The local fiber orientation within the processed beads directly impacts the mechanical and thermal performances, and correlating the orientation to processing parameter variations would lead to better part quality. This study presents a novel approach for analyzing the spatially varying fiber orientation through the use of scanning electron microscopy (SEM). This paper presents the sample preparation procedure including SEM image acquisition and analysis methods to quantify the internal fiber orientation of additively manufactured carbon fiber-reinforced composites. Large area additively manufactured beads with 13% by weight large aspect ratio carbon fiber-reinforced acrylonitrile butadiene styrene (ABS) pellets are the feedstock used in this study. Fiber orientation is quantified using the method of ellipses (MoE), and the spatial change in fiber orientation across the deposited bead cross-section is studied as a function of process parameters including extrusion speed, raster height, and extrusion temperature zones. The results in the present paper show the results from the novel use of SEM to obtain the local fiber orientation, and results show the variation in alignment within the individual processed bead as well as an overall aligned orientation state along the direction of deposition.

Evaluation of reproducible cryogel preparation based on automated image analysis using deep learning.

Cryogels represent a class of porous sponge-like materials possessing unique properties including high-fidelity reproduction of tissue structure and maximized permeability. Their architecture is mainly based on an interconnected network of macropores that provides sufficient stability while allowing the movement of substances through the material. In most cryogel applications, the pore size is very important, especially when the material is used as a 3D scaffold for tissue culture, applied as a filter, or utilized as a membrane. In this study, poly(dimethylacrylamide-co-2-hydroxyethyl methacrylate) cryogels have been prepared by two preparation methods to investigate the reproducibility of homogeneous pore structures and pore sizes. Automated image analysis algorithms were developed to rapidly evaluate cryogel pore sizes based on scanning electron microscopy (SEM) images. The quantification approach contained a unique combination of classical and deep learning-based algorithms. To validate the accuracy of the two models, we compared the results obtained from automated SEM image analysis with those from manual pore size determinations and mercury intrusion porosimetry (MIP) measurements. Effect sizes were calculated to compare the results from manual and automated pore size measurements for the cryogel reproducibility series. 81% of the values obtained revealed only trivial differences, which strongly suggests that automated image analysis can reliably substitute the manual evaluation of cryogel pore sizes. The use of an adapted reactor setup yielded cryogels with heterogeneous morphologies in the absence of recognizable pore structures. With the conventional cryogel preparation using plastic syringes, the obtained cryogels represented highly reproducible morphologies and pore sizes in the range between 17 and 22 μm. Calculated effect sizes within the cryogel replicate series revealed only trivial differences between the obtained pore sizes in 83.5% or 99.4% of the data (classical approach and deep learning-based approach, respectively).

Evaluation of Thermal and Rheological Properties of Phase Change Material-Incorporated Asphalt Mastic with Porous Fillers

Incorporating phase change material (PCM) into paving materials can regulate the pavement temperature, improve the pavement durability, and mitigate the heat-island effects. In this research, porous fillers were used as the PCM carrier, and the thermal and rheological behaviors of the asphalt mastic with the PCM were evaluated. Two different carrier materials (diatomite and expanded perlite) and four types of PCMs were used in the study. The candidate filler, PCM, and proper blending ratios were determined based on the results of scanning electron microscope image analysis, the filter paper test, and the temperature sweep test. The thermal and rheological behaviors of the mastics with PCMs were further evaluated with different filler replacement ratios. Thermal analysis through a differential scanning calorimetry test, thermal conductivity and volumetric heat capacity test, and real-time temperature performance test were performed on the asphalt mastics. Rheological tests, including the complex shear modulus test, the bending beam rheometer test, and the linear amplitude sweep test, were also conducted. The modified mastics were found to have high heat capacity with the latent heat storage ability. The rheological analyses showed that with the addition of polyethylene glycol, while the low-temperature performance of the asphalt mastics was improved, the performance at intermediate and high temperatures was not adversely affected by the PCM.

Thermal modeling for anionic surfactant using Inverse gas chromatography and image processing techniques

Anionic surfactants are one of the necessary ingredients demanded in extensive bio-and pharmaceutical industry. Their concern on human health and environmental safety get increase and is originated from its surface thermodynamic properties. Surface thermodynamic properties have severely an effect on thermodynamic and kinetic parameters in the chemical reaction. However, there is a kind of serious differences between theoretical calculation and experimental result because of lacks of understanding on complex surface thermodynamic properties. Inverse gas chromatography (IGC) is an analytic chemistry tool providing information on physicochemical and thermodynamic parameters. Herein, a thermal modeling of surface thermodynamic properties is suggested. Net retention volume, VN, of n-alkanes and polar probes upon sodium lauryl sulfate surface properties as an anionic surfactant are analyzed at diverse temperatures range from 363.15 to 433.15 K using IGC. VN of n-alkane values are employed to assess the London dispersive surface free energy, γSL by comprehensive thermodynamic models and results into the Guttmann Lewis acid-base parameters and acid-base constants. The results reveal that an excellent linear correlation coefficient value closer to 1. The current work demonstrates how to approach surface thermodynamic characteristics of anionic surfactant and suggests a new thermal model as an advanced model. Additionally, scanning electron microscopy image analysis regarding the surface morphology has been carried out using image processing techniques. Current comprehensive approach enables to analyze and apply for an effective understanding on surfactant molecules.

Effects of Surface Hydrophobicity of Lab Coat Fabrics on Nanoparticle Attachment and Resuspension: Implications for Fabrics Used for Making Protective Clothing or Work Uniform

Although nanoparticles have been incorporated in a range of applications, human exposure through surface contamination remains a concern and is under investigation. This is especially true in the context of industrial and research labs, where workers may become contaminated with nanoparticles. Development of appropriate personal protective equipment requires a deeper understanding of how nanoparticles interact with fabrics. The contamination and resuspension behavior of Al2O3, carbon black (CB), and carbon nanotubes (CNTs) with four common lab coat materials (100% cotton, 80/20 polyester/cotton blend, 100% polypropylene, and Tyvek) is presented in this study. To understand the effects of fabric weave pattern and surface chemistry on nanomaterial–fabric interactions, fabrics were treated with C3F8 or H2O(v) plasma to alter surface wettability while maintaining bulk morphology. Changes in surface chemistry and wettability were measured using X-ray photoelectron spectroscopy and water contact angle goniometry on untreated and plasma-treated materials. Contamination and release of nanomaterials were quantified by monitoring the change in mass after contamination and shaking of the fabrics and using scanning electron microscopy image analysis. Overall, the lowest contamination levels arose from exposure to CNTs. Plasma treatment results in differential contamination, with the H2O(v) plasma-treated fabrics demonstrating the lowest CB contamination, whereas the lowest Al2O3 contamination and resuspension occurs with the C3F8-plasma treated cotton. A complex mechanism for nanoparticle interaction with fabrics involving surface chemistry, morphology, and intermolecular forces is discussed. Notably, different surface treatments resulting in materials repellent to airborne particles could be used in treating fabrics used for making protective clothing or work uniforms to minimize the contamination and spread of unwanted particles.

A Comparative Study on Electrical Resistivity and Compressive Strength Properties of Cement Composites Incorporating Conductive Materials

Conductive cement composites have attracted high attention in recent years due to the possibility of achieving multifunctional materials. The usual approach has been to incorporate steel fiber, carbon fiber, graphite, and carbon nanotube/or carbon nanofiber into the cement matrix. In this article, an experimental comparative study was conducted on the electrical resistivity and compressive strength properties of cement composites incorporating carbon fiber (CF) and steel fiber (SF), which are conductive materials. The electrical resistivity of the conductive fiber-reinforced cement composites (FRCCs) was measured using the four-probe method, and compressive strength was conducted based on the KS L ISO 679 and ASTMC109/C109M test methods. Their performance was compared and analyzed with plain cement composites (PCCs). Afterwards, the fracture surfaces of the conductive SFRCCs (steel fiber-reinforced cement composites) and CFRCCs (carbon fiber-reinforced cement composites) were also analyzed using a scanning electron microscope (SEM). The experimental results showed that, in all specimens, the electrical resistivity gradually increased as the curing ages elapsed, while the electrical resistivity decreased significantly as the fiber volume fractions increased. Overall, the addition of SF up to a fiber volume fraction of 1.25% did not significantly affect the electrical resistivity of cement composites. In contrast, however, the electrical resistivity of CF decreased slightly even at a low dosage (i.e., 0.1–0.3%), and thereafter, it was significantly decreased. The percolation threshold of the conductive CFRCC incorporating CF used in this experiment was 0.4%, and this seemed to be the optimal CF dosage that can greatly improve the conductive cement composites while maintaining the maximum performance of compressive strength. In addition, the compressive strength of conductive SFRCC was higher than that of PCC, whereas in the case of conductive CFRCC, it showed a greater tendency to decrease significantly as the fiber volume fractions increased. We expect the results of SEM image analysis to be useful as basic data for establishing microstructure mechanisms of reinforcement fibers in the cement matrix.

The effects of carbonaceous inclusions and their distributions on dynamic failure processes in boron carbide ceramics

AbstractCommercially available boron carbide ceramics typically have heterogeneous microstructures that contain distributions of processing‐induced inclusions. The inclusions that are rich in carbon (i.e., carbonaceous) govern the underlying mechanisms of brittle fracture through wing crack formation, and thus dictate the mechanical response of the ceramic. In this study, we investigate the dynamic failure of five boron carbide ceramic materials with different inclusion populations. All of the materials were prepared by hot‐pressing; four of these boron carbides contained different sizes and concentrations of carbonaceous inclusions, while one contained no carbonaceous inclusions. The heterogeneity distributions were characterized in some detail for statistical analysis using scanning electron microscopy and quantitative image analysis. A modified compression Kolsky bar setup with in situ ultra‐high‐speed microscopic imaging (10 million frames per second) was then used to study the influence of the inclusion distributions on the dynamic failure processes in these materials, at nominal high strain rates of 102–103 s−1. The in situ ultra‐high‐speed microscopy highlighted the link between micro and macroscale failure processes and demonstrated that the carbonaceous inclusions are indeed the preferential sites for nucleation of wing cracks, as previously hypothesized based on post‐mortem observations. The relative orientation of an inclusion with respect to the compression axis was shown to affect the likelihood that it would participate in crack nucleation. All of the ceramics were also found to have orientation‐dependent peak compressive stress, regardless of the presence of carbonaceous inclusions, suggesting that grain orientation distributions are also important.

Innovative Tungsten Coatings for an Application in Modern and Future Fusion Devices

Tungsten is foreseen presently as the plasma-facing material for divertors in fusion power plants. In order to achieve durable operation of divertors of current fusion reactors, an efficient way of maintaining the divertor functionality is needed. A system capable of in situ tungsten coating of the divertor via low-pressure plasma spraying was proposed to maintain the divertor integrity. In this work, tungsten was deposited on NB31 carbon fibre composite substrates using the low-pressure plasma spraying technology to evaluate the feasibility of this technique. The thickness, porosity, composition, adhesion, and microstructure of the coatings were investigated by scanning electron microscopy image analysis and energy dispersive spectroscopy. Based on the initial results, the spray parameters were iteratively improved in a campaign-based study. The coatings exhibited improving properties through an adjusting of the carrier gas flow, the scanning speed, and the spray distance. By lowering the carrier gas flow, the porosity of the coatings was reduced, resulting in coatings of 98% bulk density. Adjusting the carrier gas flow reduced the amount of semi-molten particles in the coatings significantly. A decrease in both scanning speed and spray distance increased the substrate’s temperature, which led to better adhesion and porosity.

Enhanced magnetoelectric effect in Lead-Free piezoelectric BaZr0.2Ti0.8O3 − 0.5 Ba0.7Ca0.3TiO3 and Fe-rich magnetostrictive Co0.8Fe2.2-xDyxO4 nanocomposites for energy harvesting applications

The design, discovery and development of magnetoelectric (ME) composites with enhanced properties and performance opens up further opportunities to explore new scientific aspects and to develop next-generation electromagnetic devices. Nevertheless, the engineered complex ME composites with multi-phase interfacial chemistry have rarely been reported. In this context, in the present work, enhanced magnetoelectric phenomenon reported for the ME-composites made using lead-free ferroelectric phase BaZr0.2Ti0.8O3–0.5Ba0.7Ca0.3TiO3 (BZT-BCT) and magnetostrictive phase Co0.8Fe(2.2-x)DyxO4 (CFDO). The ME composites were synthesized by varying the magnetostrictive CFDO phase, where Dy(x) varied as x = 0.000(ME1), 0.025 (ME2), 0.050 (ME3) and 0.075 (ME4). The effect of varying CFDO phase on the structure, morphology, microstructure, density, piezoelectric, dielectric, ferroelectric and magnetoelectric properties of the ME-composites is evaluated. X-ray diffraction analyses of all ME-composites confirm the tetragonal structure of the BZT-BCT ferroelectric phase and spinel cubic structure of the CFDO ferrimagnetic phase. Raman spectroscopic analyses also confirm and validate the respective phases with a clear signature presence of the characteristics modes. Granular, dense microstructure with a uniform particle size distribution evidenced in scanning electron microscopy imaging analyses. The physical density measurements indicate that the ME composites attain a density in the range of 6.0–6.4 g/cm3; density increases with increasing CFDO phase. Frequency dispersion profiles of the dielectric constant exhibit a maximum dielectric constant for ME1 composite while a sharp decrease in dielectric constant at higher frequencies is noted with increasing CFDO phase in the ME-composites. Ferroelectric properties evaluated by measuring the polarization (P) – electric field (E) hysteresis loops at 300 K indicate the presence of typical P-E loops in all ME composites confirming that the ferroelectric properties are retained even after combining with the magnetic phase. The ME4 composite demonstrate a 0.573 squareness ratio, which is useful for multistate memory device applications. The ME4 composites further characterized by a moderately higher remnant polarization (Pr = 2.24 µC/cm2). All the synthesized ME-composites are promising for permanent memory storage device (FeRAM) applications. Piezoelectric coefficient measurements indicate a maximum piezoelectric coefficient of 116 pC/N for the ME4 composite while the ME-coefficient measurements demonstrate higher ME-coefficients of 250 mV/(cm-Oe) for ME2 composite. Based on the comprehensive and comparative studies of the ME-composites with variable magnetostrictive phase, the structure-chemistry-property correlation in these ME-composites established for possible applications in electromagnetic devices and energy harvesting applications.

Fabrication and investigation of physicochemical and biological properties of3Dprinted sodium alginate‐chitosan blend polyelectrolyte complex scaffold for bone tissue engineering application

AbstractIn tissue engineering technique, a biological scaffold with appropriate composition and structure for promoting growth and differentiation of cells thereby regenerating damaged tissue, is a prime necessity. In this paper, 3D‐printed scaffolds comprising sodium alginate (SA) and chitosan (CH) biopolymers of natural origin are reported. Bioinks with varying ratios of SA and CH were prepared and scaffolds were fabricated by 3D printing. The fabricated scaffolds possess many desired properties that are vital for tissue regeneration purposes. The scaffolds possess open pore microstructures with interconnected pores and desired pore size as revealed by scanning electron microscopic image analysis. The polyelectrolyte complex formation (PEC) between SA and CH as revealed by Fourier‐transform‐infrared spectroscopic analysis is favorable as it offers a better surface for cell attachment and proliferation, and an ideal microenvironment for bone regeneration. Among the scaffolds, SA/CH with 60:40 showed controlled swelling and degradation behavior, with higher tensile strength of 0.387 ± 0.015 MPa. In vitro‐biomineralization showed superior apatite layer deposition ability over the SA/CH: 60/40 scaffold surface. The fabricated SA/CH scaffolds are hydrophilic and biocompatible as evident from the contact angle, protein adsorption, MTT assay, and cell attachment studies. However, SA/CH: 60/40 is shown to have superior biological properties compared with the other SA/CH compositions. Thus, it is concluded that 3Dv printed SA/CH: 60/40 scaffold having some superior properties and bioactivity can be used as a suitable matrix for future bone tissue regeneration applications.

Reuse of tire waste in light concrete

Lightweight concrete is characterized by its low density due to the incorporation of lightweight materials such as aggregate clay or lightweight materials in general. In the city of Aracaju there are companies that promote tire reconditioning generating large amount of waste powder. This study aims to study the reuse of tire rubber waste in lightweight aggregate clay concrete. An experimental program for the analysis of these concretes was developed, varying the percentage of 1, 2.5 and 5% of the tire rubber residue in replacement of the natural fine aggregate and replacing 100% of the natural coarse aggregate with expanded clay aggregate(50% C1506 expanded clay aggregateand 50% expanded clay aggregateC2215). The materials (cement, sand, expanded clays and tire rubber residue) were characterized by granulometric analysis tests and unit mass. The hardened concrete was evaluated by mechanical tests of axial compressive strength, modulus of elasticity and tensile strength by diametral compression, physical tests of water absorption and specific mass, as well as scanning electron microscopy image analysis. The use of expanded clay aggregateand 1% of tire rubber residue ensured better mechanical strength, lower water absorption and higher specific mass than mixtures with 2.5 and 5%, reaching values close to the reference concrete, and the residue be an alternative for reuse avoiding disposal.

Visualization of styrene-butadiene rubber (SBR) latex and large-scale analysis of the microstructure of lithium-ion battery (LIB) anodes

This study presents a novel method for analyzing binder distribution in a lithium-ion battery (LIB) anode. The developed method is based on scanning electron microscope (SEM) image analysis and can be used to analyze an aqueous styrene-butadiene rubber/carboxymethylated cellulose (SBR/CMC) binder system. The main advantage of this method is that it can provide large-scale cross-sections of multiple samples in a single milling process while maintaining a high-quality cross-section enabling the clear distinction of electrode components. This minimizes the issue of SEM-based analysis in the selection of a representative analysis area. The sample preparation and image acquisition processes were optimized to obtain high-quality images, and image processing procedures were developed for quantitative analysis. Osmium tetroxide (OsO4) staining and resin embedding enabled us to achieve a smooth two-dimensional (2D) cross-section with a clear distinction of the electrode components. The milling process enabled us to produce high-quality large-scale cross-sections similar to those prepared by ion beam milling methods. It was verified that our developed method is reliable in determining the SBR content and porosity. The developed method was used to analyze the SBR distribution and pore structure of anode layers prepared at various drying temperatures.

Supramolecular Aggregation Processes on Carbon Surfaces Occurring in Bovine Serum Albumin Solutions

The processes of supramolecular aggregation occurring on carbon surfaces in aqueous solutions of bovine serum albumin (BSA) during drying were studied using modern scanning electron microscopy (SEM). The carbon materials studied were highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC). Based on the analysis of SEM images and EDX-scanning element distribution maps, a possible mechanism for the formation of the observed intricate structures on the surface was proposed. The formation of fuzzy lacy structures resembling shadow replicas was explained by relatively strong hydrophobic–hydrophobic interactions of albumin molecules with carbon surfaces.

3D modeling of PVDF membrane aging using scanning electron microscope and OpenCV image analysis

The aging of membranes compromises their integrity and reduces the quality of filtered water. In the present study, we constructed three-dimensional (3D) models of polyvinylidene fluoride (PVDF) membranes to evaluate the effects of membrane aging. Virgin and used PVDF membrane images were obtained by field emission scanning electron microscopy (FE-SEM), and the size distribution of the PVDF spherulites was analyzed using a Python-OpenCV program. Assuming a random distribution, the 3D membrane models were assessed in hydraulic and particle tracing simulations using COMSOL Multiphysics®. Compared to virgin membranes, the PVDF spherulites in the 10-year-old used membranes were enlarged and sloughed off owing to repeated filtration and backwashing. The porosity, filtration flux, and particle retention of the used membranes varied significantly more than those of the virgin membranes. Although our results were constrained by the size of the 3D membrane models and overall small sample size, our study provides an empirical basis for the 3D modeling of membranes from SEM images and our method could be applied for the optimization of membrane structure and integrity for water treatment and purification.

Condensation Characterization for PV Soiling

Condensation (dew) on PV modules greatly affects their soiling. In this study, we compared several techniques for measuring and characterization of condensation on soiled glass samples in the desert environment of Doha, Qatar. The techniques were: two types of moisture sensor; optical microscopy; scanning electron microscopy image analysis; and dew-point/surface temperatures. It was found that moisture sensors are practical and useful for measuring condensation on PV modules. As condensation increased, dust particles in the soiling layer became more tightly clustered together by the droplets, and more cementation crystal needles were generally observed. Importantly, it was found that condensation commenced when the surface temperature was several °C above the dew point, indicating it is necessary to directly measure condensation on soiled surfaces rather than estimate it from environmental conditions.

Mechanical properties and freeze–thaw resistance of polyurethane-based polymer mortar with crumb rubber powder

• • PUM is suitable for pavement repair due to its excellent ductility; • • Flexural toughness, splitting tensile strength and freeze–thaw resistance of PUM were examined; • • The flexural toughness and freeze–thaw resistance of PUM were modified by crumb rubber powder; • • The microstructure of PUM was identified by SEM image analysis; • • The mass loss of PUM at different freeze–thaw cycles was negative. In this study, it was considered that the effects of two polyurethane (PU) / sand ratios (25:100 and 35:100) and four crumb rubber powder contents (0 to 15%, 5% interval) on the flexural toughness, splitting strength and freeze–thaw resistance of polyurethane-based polymer mortar (PUM). Scanning electron microscopy (SEM) was used to analyze the microstructure of PUM. The results showed that adding crumb rubber powder improved the flexural toughness and freeze–thaw resistance of PUM. The flexural and splitting tensile strength of the two sets of PUM mixed with 5% crumb rubber powder were enhanced by 11.6% and 10.4%, 8.7% and 10.0%, respectively. Microscopic analysis showed that the internal foam pores and interfacial transition zone (ITZ) were responsible for the strength reduction in PUM. There was no peeling of specimens at corners and edges after 200 freeze- thaw cycles (FTCs), and the mass loss of PUM at different FTCs was negative. The recommended proportion of crumb rubber powder in PUM varies from 5% to 10% can serves as a pavement surface repair material.

Lithofacies and its controls on the organic matter-hosted pores in the Cambrian gas-rich Niutitang shale in upper Yangtze Plate, China

The organic-rich shale in the Lower Cambrian Niutitang Formation (Є1n) has great gas resources potential in south China but have no commercial gas production achieved yet. The EYY1 well is the first well located at the eastern edge of the upper Yangtze plate to obtain success in commercial gas production in the Niutitang Formation, providing a rare case for better understanding gas enrichment mechanism in the Niutitang shale. By observation of cores and thin sections, bulk rock X-ray diffraction mineral analysis, the Niutitang shale is classified into three kinds of organic-rich lithofacies: calcareous shale (CS), siliceous shale (SS) and transitional shale (TS). The organic matter (OM) and OM-hosted pore in different lithofacies were examined by using scanning electron microscope (SEM) with argon-ion polishing sample treating, accompanied by energy spectrum test and SEM image analysis. The results show that: (1) Shale lithofacies control the organic matter type and development degree of organic matter-hosted pores (OMPs). (2) CS have plenty of depositional organic matter (DOM) in which nano-micron sized OMPs are poorly developed with surface porosity ranges between 3.05% and 9.08%. Siliceous and transitional shale have more migrated organic matter (MOM), which possess more sponge-like nano-sized pores with surface porosities range of 10.7%–31.5%. The pore development degree and gas content of siliceous shale is higher than that of transitional and calcareous shale. (3) Organic matter abundance (TOC content), type, and mineral composition also have important constrain on OMPs development. TOC has a positive correlation to the OMPs, whereas TOC 4 wt% or so is a balance point between the influence of organic matter content and formation compaction on pore development, higher TOC cannot prevent the pore from collapsing due to compaction in this region. The OMPs associated with or adjacent to clay minerals in siliceous shale are more developed, which indicate clay minerals which have positive effects on the adsorption of organic matter and the formation and preservation of OMPs.

CHARACTERIZATION OF DIFFERENT WC-Co CEMENTED-CARBIDE TOOLS

This paper deals with the characterization of three different commercial, WC-Co cemented-carbide tools in the form of saw blades, one group of which exhibits more frequent cracking. Since the properties of these materials largely depend on the microstructure, a detailed characterization was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The SEM image analysis included a determination of the binder content and the mean WC grain area. The average chemical composition of these materials was also determined using an X-ray fluorescence (XRF) analyser. The results show that despite the same content of binder-forming elements in all three WC-Co cemented-carbide materials, the material that cracked more frequently contained a smaller amount of binder and a lower mean WC grain area, both of which are known to reduce the toughness of such a material.