Silicate Type Research Articles

Fracture Resistance of AAAS Composites with Ceramic Precursor

The paper deals with selected alkali-activated aluminosilicate (AAAS) composites based on ceramic precursors in terms of their characterization by mechanical fracture parameters. Composites made of brick dust as a precursor and an alkaline activator with a silicate modulus of Ms = 0.8, 1.0, 1.2, 1.4 and 1.6 were investigated. The filler employed with one set of composites was quartz sand, while for the other set it was crushed brick. The test specimens had nominal dimensions of 40 × 40 × 160 mm and were provided with notches at midspan of up to 1/3 of the height of the specimens after 28 days. 6 samples from each composite were tested. The specimens were subjected to three-point bending tests in which force vs. displacement (deflection at midspan) diagrams (F–d diagrams) and force vs. crack mouth opening (F–CMOD) diagrams were recorded. After the correction of these diagrams, static modulus of elasticity, effective fracture toughness, effective toughness and specific fracture energy values were determined using the Effective Crack Model and the Work-of-Fracture method. After the fracture experiments, informative compressive strength values were determined from one of the parts. All of the evaluations included the determination of arithmetic means and standard deviations. The silicate modulus values and type of filler of the AAAS composites significantly influenced their mechanical fracture parameters.

Luminescence of a laser dye in organically-modified layered silicate pigments

The main focus of the present work was the development of pigments based on layered nanomaterials exhibiting luminescent properties. Two layered silicates, montmorillonite (Mt) and saponite (Sap), differing in their cation exchange capacity (CEC), were modified with cationic organic surfactants (tetraoctylammonium and tetraoctylphosphonium) in various amounts relative to the CEC (25–100%) and with a laser dye, rhodamine 6G (R6G), with dye/silicate ratios of 0.001–0.08 mmol g−1. The photoluminescence and its dependence on the surfactant amount, dye concentration, and the layered silicate type were evaluated. Modification by the surfactants played a key role and caused an increase in fluorescence, particularly for Mt, whose hybrids were non-active without the modification. The intensity increased significantly even for samples modified with amounts of surfactants equal to 25% of the CEC values. Dye concentrations above 0.02 mmol g−1 caused a diminishing of the fluorescence intensities due to the formation of non-luminescent molecular aggregates of the dye. Advanced chemometric and statistical analysis was applied for better differentiation of the components in fluorescence spectra. By selecting suitable organic cation and dye components, it was possible to prepare pigments exhibiting high fluorescence and at (for R6G) unusually long wavelengths, approaching the near-infrared region (650–700 nm).

ВУЛКАНОГЕННЫЕ ПРОСЛОИ В БАЖЕНОВСКОЙ СВИТЕ ЗАПАДНО-СИБИРСКОГО ОСАДОЧНОГО БАССЕЙНА

Актуальность. Детальное изучение вещественного состава и особенностей строения выделенных в отложениях баженовской свиты вулканогенных горизонтов позволит уточнить закономерности их регионального формирования и распределения на территории Западно-Сибирского осадочного бассейна, а также получить новые данные о вулканизме, проявленном в верхнеюрское время на территории исследования. Цель: определение особенностей состава и строения аномально люминесцирующих горизонтов баженовской свиты, доказывающих их вулканогенное происхождение, а также поиск закономерностей их распределения на территории исследования. Объекты: осадочные породы, люминесцирующие прослои и вмещающие отложения баженовской свиты. Методы: рентгенофазовый анализ, петрографический анализ. Результаты. В центральной и юго-восточной части Западно-Сибирского осадочного бассейна в отложениях баженовской свиты обнаружены люминесцирующие в ультрафиолетовом освещении прослои мощностью 0,2–45 см. Изучение минерального состава, особенностей строения и структурно-текстурных признаков выделенных горизонтов позволило определить природу их образования как вулканогенно-пирокластическую. Предполагается, что исследуемые прослои образовались в результате диа- и катагенетического преобразования вулканокластического материала туфовых осадков в обстановке застойного моря с высоким содержанием органического вещества. По результатам проведенных исследований выявлены два типа вулканогенных горизонтов, которые отличаются друг от друга по минеральному, петрографическому и химическому составу. Первый горизонт отнесен к глинистому типу. Он сложен в основном глинистыми минералами (каолинитом и смешаннослойными минералами иллит-смектитового ряда) с примесью обломочного алевритового материала. Второй горизонт характеризуется преимущественно кремнистым (кварцевым) составом и отнесен к кремнистому типу. Каждый из выделенных горизонтов обособлен в разрезе и соответствует своему вулканическому событию позднеюрского времени.

The carbon stable isotope compositions of glyphosate and aminomethylphosphonic acid (AMPA): Improved analytical sensitivity and first application to environmental water matrices.

The presence of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) in the environment has adverse effects on environmental quality, raising the need to better constrain their fates, in particular the processes that control their production and degradation. Our aim was to improve the sensitivity of their δ13 C analysis and demonstrate the feasibility of measuring them in natural surface water. The δ13 C values of dissolved glyphosate and AMPA were determined using isotope ratio mass spectrometry (IRMS) (Delta V Plus instrument) coupled to a high-performance liquid chromatography (HPLC) unit, where glyphosate and AMPA were separated on a Hypercarb column. We demonstrated an improved sensitivity of the δ13 C analysis for glyphosate and AMPA by LC/IRMS compared with previous studies. For waters from the carbonate and silicate hydrofacies, while no pretreatment was required for the isotope analysis of glyphosate, removal by H3 PO4 acidification of dissolved inorganic carbon, that co-elutes with AMPA, was required prior to its analysis. We successfully tested a freeze-drying pre-concentration method showing no associated isotope fractionation up to concentration factors of 500 and 50 for glyphosate and AMPA, respectively. We demonstrated, for the first time, the feasibility of measuring the δ13 C values of glyphosate and AMPA in natural surface waters with contrasted hydrofacies (calcium carbonate and silicate types). This opens new fields in pesticide research, especially on the characterization of processes that control their degradation and the production of their secondary byproducts.

Microwave Heating of Cordierite Ceramic Substrate for After Treatment Systems

Selective catalyst reduction is one of the most affordable and successful technologies aimed at reducing NOx emissions from diesel engines. However, the reduction process can be achieved if a certain temperature is reached for the ceramic substrate of the catalytic core. The required temperatures for catalytic reaction vary from 2500 C to 4500 C depending on the technology applied in the catalytic processes. This paper aims at presenting preliminary research in microwave cordierite heating, which is a type of magnesium aluminium silicate used as ceramic honeycomb substrate (catalyst monolith) in the after treatment system in the automotive industry. The research focused on testing the Mg2Al4Si5O18 composite material (cordierite) for different microwave heating regimes in order to establish the level of microwave power required for fast heating. This application will be subject for the further development of new MW-SCR after treatment systems in order to reduce the NOx emissions at cold start engine or low operating regimes of non-road mobile machinery engines. The ceramic composite material was heated for 5 levels of microwave power, from 600 W to 1400 W, using a 6 kW microwave generator coupled with a matching load impedance tuner, and the temperatures were recorded using an IR pyrometer.

Organic Material on Ceres: Insights from Visible and Infrared Space Observations.

The NASA/Dawn mission has acquired unprecedented measurements of the surface of the dwarf planet Ceres, the composition of which is a mixture of ultra-carbonaceous material, phyllosilicates, carbonates, organics, Fe-oxides, and volatiles as determined by remote sensing instruments including the VIR imaging spectrometer. We performed a refined analysis merging visible and infrared observations of Ceres’ surface for the first time. The overall shape of the combined spectrum suggests another type of silicate not previously considered, and we confirmed a large abundance of carbon material. More importantly, by analyzing the local spectra of the organic-rich region of the Ernutet crater, we identified a reddening in the visible range, strongly correlated to the aliphatic signature at 3.4 µm. Similar reddening was found in the bright material making up Cerealia Facula in the Occator crater. This implies that organic material might be present in the source of the faculae, where brines and organics are mixed in an environment that may be favorable for prebiotic chemistry.

Geochemistry of Platinum-Group Elements (PGE) in Cerro Matoso and Planeta Rica Ni-Laterite deposits, Northern Colombia

Platinum-group elements (PGE) are included among the so-called critical metals, and are essential metals for the technological industry. However, there are very few deposits in the world from which these metals can be extracted. The present work investigates three Ni-laterite profiles (hydrous Mg silicate type) formed over the ultramafic rocks of Cerro Matoso and Planeta Rica in Colombia. The main goal is to determine their PGE concentration and distribution, as well as to identify the carrier phases of these noble metals. The highest PGE contents in Cerro Matoso and Planeta Rica are concentrated in the limonite horizon (141–272 ppb), showing a strong decrease towards the saprolite and the underlying serpentinized peridotite (parent rock; < 50 ppb). The highest concentrations correspond to Pt>Ru>Pd and the lowest to Rh<Os<Ir. Such distribution indicates that PGE are mobilized in different proportions by the laterization processes. The high affinity between PGE and Fe favors the formation of PGE-Fe mineral alloys such as the Pt-Ir-Fe-Ni minerals hosted by Fe-oxyhydroxide found in the limonite–saprolite transition zone in Planeta Rica. In addition, in the same zone, nanoparticles of Pt (< 1 µm) were found within framboidal pyrite. Both types of platinum group minerals (PGM) are secondary in origin. In the case of Pt-Ir-Fe-Ni alloys, this interpretation is supported by their morphology and chemical composition, which is comparable with PGE-Fe-Ni alloys found in laterites of Dominican Republic. In the case of Pt nanoparticle, textural relations suggest the neoformation of PGM adhered to the porous edges of altered pyrite. Cerro Matoso and Planeta Rica should be considered as unconventional PGE deposits, if adequate recovery processes can be applied for their recovery as by-products during Ni (+Co) production.

Properties and Applications of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biocomposites

Polyhydroxyalkanoates (PHAs) are biopolyesters accumulated by microorganisms as intracellular storage materials and they have attracted attention as “green plastic” alternatives to their petrochemical counterparts. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, is one of the most studied members of the PHAs family, with numerous applications. PHBV has three main features, biodegradability, biocompatibility and it is a biobased polymer (biosynthesis starting from renewable resources). These three features altogether qualify PHBV as a very promising polymer that has great potential to replace conventional non-degradable polymers, and to play a significant rule in the circular economy concept. However, PHBV has some prominent disadvantages that limit its wide utilization for commercial use, these drawbacks are mainly weak mechanical properties, low thermal stability, difficult processability and considerable hydrophobicity. In order to overcome the properties issues, to produce materials with more desirable features and to engineer purpose-specific PHBV-based systems, much research has been focused on improving its properties by forming composites and to utilize these produced composites for a wide spectrum of very promising applications. The purpose of the current work is to compile and classify the research accomplished in the field of PHBV biocomposites and their applications in different disciplines. It was found that many different types of nanofillers, natural fibers, agricultural waste, clay, silicate, wood and cellulose derived natural materials have been successfully incorporated into PHBV matrix. The resultant biocomposites were characterized, tested and found promising to be utilized in a wide spectrum of applications, namely packaging, tissue engineering and drug delivery systems. The potential benefits of PHBV-based biocomposites make a strong case for research into this area. Therefore, further research works need to be conducted in order to find new PHBV biocomposite materials for advanced applications.

In-situ water-immersion experiments on amorphous silicates in the MgO–SiO2 system: implications for the onset of aqueous alteration in primitive meteorites

Amorphous silicates, abundant in primitive carbonaceous chondrites, are among the most primitive materials from the early Solar System. They show evidence of some aqueous alteration in the meteorite parent bodies, but it is not clear how this highly reactive material changed at an early stage after contact with water. Herein, we report in-situ experiments on the aqueous alteration of amorphous silicate nanoparticles (typically 70 nm in diameter); we used two different compositions that are similar to forsterite (MgO/SiO2 = 2.02) and enstatite (MgO/SiO2 = 1.15) in the simple MgO–SiO2 system to understand basic reaction principles at the onset of the aqueous alteration. The experiments were performed in pure water at room temperature using X-ray diffraction (XRD), transmission electron microscopy (TEM), and pH measurements. The in-situ TEM images of the nanoparticles—in particular those with the forsterite composition—gradually became difficult to recognize in water. The pH value of the water also increased with time, suggesting that preferential Mg2+ dissolution occurred from the amorphous silicates right after mixing with water. The in-situ XRD patterns showed that magnesium silicate hydrate (M-S-H), which is a poorly crystalline phase like a phyllosilicate, newly appeared. The M-S-H seems to have been formed via a dissolution–precipitation process. Its formation rate from amorphous silicates was considerably higher than from crystalline silicates, because amorphous silicates are highly metastable and have high solubility in water. M-S-H formation from the forsterite composition, which has a highly unstable amorphous structure, is ten times faster than from the enstatite composition. The M-S-Hs show string-like or tiny fragmental textures in the final dried products that are very similar to those observed in the matrices of some primitive carbonaceous chondrites. M-S-H would have been the initial product formed in the aqueous alteration of amorphous silicates in the meteorites; thus, it is an important tracer of early aqueous activity at low temperatures in the early Solar System. By comparing the in-situ observations with those obtained after drying the experimental samples, we found two types of M-S-Hs: epigenetic M-S-Hs—which have a slightly Si-rich composition—formed during drying, and syngenetic M-S-Hs formed by in-situ alteration. Carbonaceous chondrites may also contain these two types of hydrous silicates, and this should be investigated to understand the conditions for aqueous alteration in the early Solar System in more detail. The present study clearly showed the importance of Mg/Si ratio in the precursor materials, although the actual chondrites are in more complicated multi-component system. Future experiments based on the present results can extend the investigation to the system containing Fe, S, and other components as in carbonaceous chondrites.

Moisture Influence on Compressive Strength of Calcium Silicate Masonry Units-Experimental Assessment and Normative Calculations.

This paper primarily assesses the scale of adverse changes to the compressive strength of different types of silicates due to the influence of moisture. The study covers three groups of silicate units of different strength classes—15, 20 and 25—obtained from three different manufacturers. It was demonstrated that in all studied groups, moisture significantly decreased the compressive strength by about 30–40%. In addition, microstructural studies were conducted to analyze the relationship between the specific porosity structure of each group of silicate bricks and their compressive strength. On the basis of SEM (Scanning Electron Microscopy) and EDS (Electron Dispersive Spectroscopy) analysis, the elemental composition of individual silicates was determined and the contact zone between the aggregate and the binder was determined, which largely influenced the obtained compressive strength of each silicates. Next, the study referred to the utility of the normative procedure used to determine the strength class of samples with different geometries and at different moisture concentrations. The results of the calculations showed the high accuracy of the normative-based assessment of strength class, regardless of the manufacturer and the moisture values during examination.

Facile Hydrothermal Procedure for the Synthesis of Sodium Aluminum Silicate Hydrate/Analcime and Analcime for Effective Removal of Manganese(II) Ions From Aqueous Solutions

In this research, sodium aluminum silicate hydrate/analcime composite (abbreviated as S/A) and analcime (abbreviated as A) products were fabricated utilizing the hydrothermal technique in the absence and presence of glutamine (concentration = 0.0435 g/mL) as phase-controlling template, respectively. Glutamine behaves as a crowning agent and avoids the accretion of particles. Hence, it controlled the morphology, aluminum silicate type, and crystallite size. The patterns of XRD elucidated that the S/A composite and A products exhibit a crystallite size equals 70.36 and 80.24 nm, respectively. Besides, the SEM elucidated that the S/A composite comprised of an irregular and sphere forms with a size of 2.64 µm whereas the A product comprised of a droxtal forms with a size of 7.84 µm. Furthermore, the fabricated products were exploited for removing Mn(II) ions from aqueous solutions. The uptake of Mn(II) ions was constrained by the pseudo-second-order model and Langmuir isotherm. Besides, the uptake of Mn(II) ions was exothermic since the estimations of ∆H° on account of S/A composite and A product were − 52.059 and − 58.878 kJ/mol, respectively. Additionally, the maximum uptake capacity of S/A composite and A product was 75.188 and 60.241 mg/g, respectively. The higher uptake of the S/A composite can be explained by the fact that the S/A composite has a small crystallite size (70.36 nm) and a high surface area (20.26 m2/g) compared to the A product. Furthermore, the fabricated products are returnable, stable, effective, and can be reutilized more than once without the concession of their efficacy regarding Mn(II) ions.

Effects of hollow microsphere surface property on the mechanical performance of high strength syntactic foams

Syntactic foams (SF) with robust impermeable hollow microspheres as density adjuster have drawn much attention because of their easy-tailored low density, high mechanical strength and excellent performance especially when used in high pressure aqueous environment. In this work, specially fabricated hollow silicate glass microspheres (HSMs) with high strength to weight ratio were employed for the controlled fabrication of high strength lightweight syntactic foams. Special attention has been paid on the effects of surface physicochemical status modification of the HSMs on the mechanical strength and mechanical performance evolution in various external environments. It is found that the surface physicochemical status modification of the HSMs contributes more on the enhancement of the fracture toughness compared with that of the compressive strength. Moreover, compared with those of the pristine SF, the mechanical strength of the SF samples after different environmental exposure display a more remarkable improvement due to the surface physicochemical status modification of the HSMs, indicating an enhanced environmental stability. This work provides an additional insight to the mechanical strength and aging resistance control of SF, which holds the potential to be extended to the property improvement of similar composites with various types of silicate or glass fillers.

Compressive strength of different tricalcium silicate–based materials used for primary teeth: in vitro study

Background and Objectives: One of the most universally accepted properties of a material is to have a good physical and mechanical properties to withstand the masticatory forces which is one of the major problem in dentistry. The objective of this study was to evaluate and compare the compressive strength of three different types of Tricalcium silicate based materials: (High plasticity repair mineral trioxide aggregate, ProRoot and Biodentine). Materials and methods: Ninety samples from studied materials (4mm diameter and 6mm height) were selected and divided into three equal groups according to the materials used then after each group was divided into three equal sub-groups according to the time (1 day, 1 week and 3 weeks). Compressive strength was evaluated in accordance with ISO 9917-1: 2007 recommendation. Specimens were crushed along their long axis using a universal testing machine. The load was recorded in mega Pascal. Statistical package for the social science (SPSS version 23) program was used to perform the statistical. Results: Biodentine showed significantly the highest compressive strength values than the other materials (P < 0.001), whereas High plasticity repair MTA have the lowest compressive strength values. There was no significant difference between ProRoot and HP Repair MTA-angelus. The compressive strength of ProRoot MTA was significantly lower than Biodentine but significantly higher than HP repair MTA Angelus. Conclusion: Biodentine and ProRoot have better in mechanical properties than the HP Repair MTA. The time had correspondingly effectively increased impact on the dental materials used in this study.

Bioactive Glasses and Glass/Polymer Composites for Neuroregeneration: Should We Be Hopeful?

Bioactive glasses (BGs) have been identified as highly versatile materials in tissue engineering applications; apart from being used for bone repair for many years, they have recently shown promise for the regeneration of peripheral nerves as well. They can be formulated in different shapes and forms (micro-/nanoparticles, micro-/nanofibers, and tubes), thus potentially meeting the diverse requirements for neuroregeneration. Mechanical and biological improvements in three-dimensional (3D) polymeric scaffolds could be easily provided by adding BGs to their composition. Various types of silicate, borate, and phosphate BGs have been examined for use in neuroregeneration. In general, BGs show good compatibility with the nervous system compartments both in vitro and in vivo. Functionalization and surface modification plus doping with therapeutic ions make BGs even more effective in peripheral nerve regeneration. Moreover, the combination of BGs with conductive polymers is suggested to improve neural cell functions at injured sites. Taking advantage of BGs combined with novel technologies in tissue engineering, like 3D printing, can open new horizons in reconstructive approaches for the nervous system. Although there are great potential opportunities in BG-based therapies for peripheral nerve regeneration, more research should still be performed to carefully assess the pros and cons of BGs in neuroregeneration strategies.

Investigation of high-temperature chemical interaction of calcium silicate insulation and cesium hydroxide

ABSTRACT The interaction of cesium hydroxide and a calcium silicate insulation material was experimentally investigated at high-temperature conditions to evaluate the possibility of unprecedented cesium retention under severe accident of boiling water reactor. The temperature where the interactions occurred and chemical species of cesium after the interaction were examined in this study. A thermogravimetry equipped with differential thermal analysis was used to analyze thermal events in the samples of mixed calcium silicate and cesium hydroxide under oxidizing and reducing atmospheric conditions with a maximum temperature of 1100°C. Before being mixed with cesium hydroxide, a part of calcium silicate was pretreated at high temperature to evaluate the effect of possible structural changes of this material due to a preceding thermal history and also for the sake of thermodynamic evaluation. It was found that for the original material, as xonotlite (Ca6Si6O17(OH)2) crystal, the endothermic reaction with cesium hydroxide occurred over the temperature range 575–730°C; meanwhile, for heat-treated material, which varied the crystal phase of original material to wollastonite (CaSiO3), the interaction occurred over the temperature range 700–1100°C. The X-ray diffraction analyses have indicated that both types of calcium silicates regardless of the atmospheric conditions, cesium aluminum silicate, CsAlSiO4, was formed with aluminum in the samples as an impurity or adduct. The insolubility of this formed cesium suggested the potency of cesium localization in the primary containment vessels on other structural materials that possess similar elements to that of calcium silicate insulation; hence, an effective decommissioning process could be developed.

Nonmetallic inclusions in rails made of electro-steel alloyed with chromium

Type, relative concentration and size of most characteristic non-metallic inclusions for the elements of rails (head, web) from electro-steel of E79KhF and E90KhАF grades were determined on the basis of metallographic (with a microscope “OLYMPUS GX-51”) and spectral (using spectrometer “ARL iSpark” method “Spark-DAT”) analyses. It was found that the highest relative concentration of manganese sulfides (MnS) is 30.8 – 43.4 ppm. At the same time, 60 – 100 % of inclusions of this type are of small sizes (less than 4 μm), and it does not allow them to be detected using standard metallographic analysis with 100-fold magnification. The revealed high relative concentration of sulfide inclusions directly correlates with the established positive sulfur liquation in considered rail elements, which is up to 40 %. Despite the high concentration of manganese sulfides, their influence on the quality of rails can be considered not dangerous, taking into account their high ductility during hot deformation and the established prevalence of inclusions of this type with small size (less than 4 μm). Among inclusions of a silicate type, SiO2 inclusions (3.4 – 14.9 ppm) have a significant concentration. All detected inclusions of this type have a size not exceeding 4 μm. It was found that the concentration of complex inclusions containing alumina (Al2O3 – CaO – MgO, Al2O3 – CaO – MgO – CaS, Al2O3 – CaO, Al2O3 – MgO) is insignificant: in total it does not exceed 3.1 ppm and 1.6 ppm for individual types. The concentration of corundum (Al2O3) is also insignificant and does not exceed 0.3 ppm. In this case, alumina inclusions of small size (less than 6 μm) prevail. Due to the low contamination (taking into account the relative concentration and size of inclusions) with non-plastic silicate and alumina non-metallic inclusions, their influence on the quality of the rails was not significant. It is confirmed by the absence of defects detected during ultrasonic testing.

Chapter 10 Mineral resources and prospectivity of the ultramafic rocks of New Caledonia

Abstract The main metallic mineral resources of New Caledonia are hosted by the obducted Peridotite Nappe. Ni, Co, Cr and the Pt group elements (PGEs) are specific to this ultramafic terrane. Cr, as podiform chromitite in the uppermost mantle, is the only hypogene metal mined economically in the past. The largest chromitite deposits are located in the lherzolitic Tiébaghi Massif. Supergene Ni and Co deposits are concentrated by the tropical climate that has prevailed since the Miocene. New Caledonian lateritic Ni deposits account for 10% of the global Ni resources. Hydrous Mg silicate and oxide types coexist in a single deposit. A local genetic model based on geomorphological evolution is proposed. Sc is a prospective resource associated with these supergene deposits. The PGEs are a prospective resource associated with chromite, with potential in the hypogene, supergene and fluvio-littoral domains. Pt and Pd are the most significant elements. The transition zone between the upper mantle and crustal cumulates constitutes a regional Pt–Pd-enriched horizon. The concentrations are related to small disseminated chromite lenses in a pyroxene-rich lithology. The PGEs are concentrated in weathering profiles. The value of chromite-rich sands as placers or sand beach deposits might be enhanced by the occurrences of PGEs.

The role of nanomaterials in reducing moisture damage of asphalt mixes

Interest of researchers in using nanomaterials in asphalt mixes is increasing rapidly. In this research, the effects of using various nanomaterials in asphalt mixes were investigated. In addition, the effects of two different types of fillers at their conventional size and their nano-size in asphalt mixes were tested. Four types of nanomaterials, namely nano-CaCO3, nano-hydrated lime, nano-bentonite and nano-silica, and two types of anti-stripping fillers, namely hydrated lime and CaCO3 were selected. Nano-hydrated lime was produced using a planetary ball mill apparatus. In producing nano-hydrated lime, optimum combinations of the main parameters that affect particle size reduction in milling process were determined applying trial and error procedure. Minimum particle size of the produced nano-hydrated lime was determined using Scanning Electron Microscope (SEM) and Dynamic Light Scattering (DLS) tests. From these tests, sizes of 125 and 208 nm were recorded, respectively.With applying Field-Emission Scanning Electron Microscopy (FE-SEM) technique, homogenous distribution of the additives in a 60–70 bitumen binder was verified. Asphalt concrete mixes were prepared using the above additives and a siliceous type aggregate. Moisture damage of different mixes was evaluated applying modified Lottman test at different Freeze-Thaw (F-T) cycles. F-T cycles results indicated that Indirect Tensile Strength (ITS) values were reduced appreciably at the first cycle. In fact, it was shown that 4% nano-hydrated lime exhibited the most resistance against different F-T cycles. In addition, Indirect Tensile Stiffness Modulus (ITSM) test was performed at 25 °C. From these tests, Tensile Strength Ratio (TSR) and Index of Retained Resilient Modulus (IRMr) parameters were determined. Testing results indicated that by adding 20% hydrated lime filler and 4% nano-hydrated lime to the binder, TSR values of mixes increased to some 60%. In the case of using CaCO3 filler and nano-CaCO3, 60% increase in TSR, was achieved when either 5% CaCO3 filler or 4% nano-CaCO3 were used. These results were validated performing resilient modulus test. IRMr of mixes containing 20% hydrated lime filler and 4% nano-hydrated lime increased to 56% and 60%, respectively. IRMr values of asphalt mixes increased to 48% and 54% where 5% CaCO3 filler and 4% nano-CaCO3 were added, respectively.

The ash-quartz sand interaction behaviours during steam gasification or combustion of a freshwater and a marine species of macroalgae

The interactions between ash and quartz sand as the bed material were studied for two species of macroalgae, Oedogonium intermedium (a freshwater species) and Derbesia tenuissima (a marine species). The interaction tests were performed in a lab-scale, fixed-bed reactor under a steam gasification (50% v/v steam) or a combustion (5% v/v O2) atmosphere at 900 °C for different reaction times (10 min to 6 h). For both macroalgae, some of the Na and K are found to interact with other elements, such as Mg, Si, P, Ca and Fe to form ash particles. For ODN, these low melting-point phosphorus-rich ash particles are present in sufficient quantities to adhere to the quartz sand and form agglomerates via a melting-induced mechanism. In addition, some of the Na and K react with Si from the quartz sand to form a coating layer, which promotes a coating-induced mechanism. Both mechanisms contribute to a similar extent for ODN; while the coating-induced mechanism dominates for Deb, which includes the diffusion of some Ca into the coating layer. For Deb, the steam gasification atmosphere significantly affects the size of the agglomerates, the mass fractions of K and Na retained in the agglomerates and the formation of various types of silicates in the agglomerates, when compared with those under the combustion atmosphere. However, the influence of the steam gasification atmosphere on both the morphology and the elemental composition of the ODN agglomerates is less obvious. For Deb, a high content of S is detected for the individual separate ash particles within the agglomerates during combustion, whereas negligible S is found during steam gasification.

An inorganic route to decorate graphene oxide with nanosilica and investigate its effect on anti‐corrosion property of waterborne epoxy

This paper reported an inorganic route that uses potassium silicate, which is one type of alkali silicate as an inorganic modifier, taking advantage of its instability and water condensation to decorate graphene oxide (GO) with nano‐SiO2. The ingredients of prepared nanocomposites were characterized by Fourier‐transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS), and the thermodynamic property was tested by thermal gravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to observe the morphology of SiO2‐GO nanocomposites. All the analyses above revealed the nano‐SiO2 (&lt;100 nm) was deposited on the surface of GO by chemical bonds. In the meantime, the dispersion test illustrated that nano‐SiO2 played an important role in improving the dispersity of GO. The effect of SiO2‐GO nanocomposites on barrier and corrosion protection performance of SiO2‐GO nanocomposites was tested by immersion experiment and electrochemical impedance spectroscopy (EIS). The results indicated that GO was helped to block the corrosion of aggressive medium; moreover, SiO2‐GO nanocomposites had the best anticorrosion performance and the slowest rate of corrosion because of its good dispersity with waterborne epoxy coatings.