Blended Mixtures Research Articles

Alkyl Dicarbonate-Based Electrolytes Can Enable Long-Lived Li-Ion Cells at High-Temperatures

Alkyl dicarbonates are known electrolyte degradation products produced in Li-ion cells that use ethylene carbonate (EC) and dimethyl carbonate (DMC) as electrolyte components. Also referred to as dimerization compounds, dimethyl 2,5-dioxahexanedioate (DMOHC) and diethyl 2,5-dioxahexanedioate (DEOHC), were investigated as a possible sole electrolyte solvent or and one component of a blended solvent mixture, when mixed with linear carbonates. The viscosities of DMOHC and DEOHC were measured in this report and compared to the predictions of the Advanced Electrolyte Model1, along with the two alkyl dicarbonates mixed with lithium salts and other common electrolyte solvents. Electrolytes based on DMOHC or DEOHC alone exhibit much higher viscosity than conventional EC-based electrolytes at room temperature. Thus, for testing, LiNi0.5Mn0.3Co0.2O2/graphite (NMC532), LiNi0. 83Mn0. 6Co0. 11O2/graphite (Ni83) and LiFePO4(LFP)/graphite cells with DMOHC were tested at 70°C and 85°C using C/20 charge and discharge rates.DMOHC and DEOHC were mixed with two different electrolyte salts. First, the common LiPF6 salt and the second, lithium bis(fluorosulfonyl)imide (LiFSI), both with 2% vinylene carbonate (VC). These two electrolytes were tested in NMC532/graphite cells cycled to 4.3V at a C/20 charge/discharge rate and 70°C. Cells with DMOHC and LiFSI showed considerable improvements in capacity retention compared to those filled with an EC-based electrolyte with LiPF6 salt, also cycled at 70°C. The same conclusion was found with NMC532 cells filled with DEOHC with LiFSI salt or LiPF6. Figure 1a shows the fractional capacity versus time for NMC532/graphite, Ni83/graphite and LFP/graphite pouch cells with 1.0 M LiFSI in DMOHC with 2% VC (vinylene carbonate) and 1% DTD (ethylene sulfate) additives tested at C/20 and 85°C. These cells were tested to upper cut-off potentials of 3.8, 3.9 and 3.65 V respectively. In addition, Figure 1b shows the corresponding voltage polarization results. Results show that Ni-containing cells experience exceptional lifetimes and low impedance growth despite the high cycling temperature. DMOHC-containing cells have since been tested up to 100°C. DMOHC was most advantageous for mitigating severe gassing at high temperatures. Ex-situ gas experiments show DMOHC-containing Ni83 cells produce the least amount of gas even at high voltage (4.0 V) compared to cells using EC-based electrolytes. Ni-containing cells operating to low voltage limits show unprecedented cycling lifetimes when using DMOHC electrolytes containing LIFSI while also exhibiting limited gassing. To mitigate the high viscosity of DMOHC, various cells were filled with electrolytes that used DMOHC and various percentages of diethyl carbonate (DEC) and dimethyl carbonate (DMC) with LiFSI as the salt. DMC/DEC was chosen for its low viscosity and its ionic conductivity. Even with DMC, the cycling performance showed improvements over traditional EC-based electrolytes. There were slight decreases in performance compared to a cell with a pure DMOHC electrolyte. In addition, various additives were tested, including prop-1-ene-1,3-sultone (PES), to see if gassing could be further limited. We propose DMOHC and DEOHC as new solvents for Li-ion cell electrolytes, possibly replacing EC, to enable long-lasting, high-temperature tolerant Li-ion cells. REFERENCES E. R. Logan, E. M. Tonita, K. L. Gering, and J. R. Dahn, J Electrochem Soc, 165, A3350–A3359 (2018). Figure 1. (a) Normalized capacity versus time for LFP (blue), NMC532 (red) and Ni83 (black) artificial graphite cells, using 1M LIFSI DMOHC 2%VC 1%DTD electrolyte cycling at C/20 and at 85°C. (b) corresponding voltage polarization data versus time. Figure 1

Investigating the role of aliphatic olefins in fouling of thermally cracked bitumen by testing fouling tendency of model aliphatic olefin compounds in light fractions

Olefins are considered non-desirable compounds that are formed in the thermal cracking step of crude oil. Due to their high reactivity, they are linked to the fouling tendency of thermally cracked petroleum products. In this work, the role of aliphatic olefins in the fouling of thermally cracked petroleum products is studied by investigating the fouling tendency of model aliphatic olefin compounds blended with Western Canadian Select (WCS) crude, a low-fouling material, in an Alcor hot liquid process simulator (HLPS) fouling testing apparatus. The tested model olefin compounds were selected to have different types (mono-olefin, conjugated diolefins, non-conjugated diolefins), structures, and boiling points. The model olefin compounds were tested individually and in mixtures to determine the fouling tendency. Moreover, a light fraction of thermally cracked bitumen, which contains a significant concentration of olefinic species, was blended with the heavy fraction of WCS to simulate a thermal cracking derived olefin sample with a reasonable olefin content. Olefin and olefin mixture blends were tested in the Alcor HLPS unit to determine the temperature drop (ΔT) due to fouling on the heated rod of the Alcor HLPS unit that leads to a reduction in the heat transfer coefficient. All tested samples resulted in low or low-medium fouling when compared to a thermally cracked bitumen. The results indicated that aliphatic olefins, in the low boiling range, were not the sole contributor to fouling and other constituents, such as asphaltenes or high molecular weight olefins in the heavy fractions, and other properties, such as product stability (measured by P-value), might have a synergetic effect with olefins in the fouling mechanism. Therefore, the role of aliphatic olefins in fouling in petroleum products is reduced in the absence of the aforementioned constituents and properties.

Eco-efficiency evaluation of sustainable self-compacting concrete using magnesite mine waste

Utilization potential of industrial by-products/wastes as construction material requires adequate workability, strength and other required properties as specified by standard codes of practice and certain sustainability criteria. Coal combustion byproduct (fly ash) and mine waste are a few of the abundantly available wastes that create a challenging task in their disposal with the current practice of dumping on-sites and landfilling. This study enumerates the suitability of utilizing magnesite mine wastes in self-compacting concrete (SCC) as binder and aggregate replacements by considering the evaluation factors such as fresh, hardened properties, life cycle assessment (LCA) and eco-efficiency. The results from the experimental investigation revealed that aggregate blended SCC performed well in terms of both fresh and mechanical properties, while cement blended mixtures exhibited satisfactory results. Additionally, fly ash and magnesite mine waste substantially reduced CO2 emissions and costs with added strength benefits. Eco-efficiency evaluation of mine waste blended SCC reported up to 75% higher efficiency than conventional SCC.

Fabrication of Zein/PVA Fibre Blends: Optimizing Concentration and Applied Voltage

Abstract: The fabrication of polymer fibre blends has gained much attention for the development of innovative nanomaterials. Polymer fibre blends are nanomaterials with different functionalities and properties such as a sizeable surface-to-area ratio, high porosity, flexibility, and stability. The focus of this study was to produce zein/PVA fibre blends using the electrospinning technique and varying parameters such as concentration and applied voltage. The two parameters are key driving factors for the production of fibres. Zein as a natural polymer has challenges in developing fibre materials which require artificial polymer like PVA to create a good blending mixture for electrospinning. Methods: The zein/PVA nanofibre blends were fabricated using the electrospinning technique. The FE-SEM (Leo, Zeiss) was used to study the surface morphologies of the zein/PVA nanofibers blends. The optical properties of the nanofibre blends were determined using the UV-vis spectrophotometer and the chemical structure and composition of zein/PVA nanofibers blends were studied using Thermo Scientific Nicolet iS50-FTIR spectrometer, universal ATR with the diamond detector. Results: The SEM images showed smooth zein/PVA ribbon-like nanofibre blends of 90/10, 80/20, 70/30, 60/40, and 50/50. SEM images of zein/PVA (80/20) electrospun at 25 kV were obtained to be the maximum fibre yield due to zein/PVA compatibility, increased conductivity, and enhanced fibre formation. The optical properties (absorption spectroscopy) suggested that the zein/PVA (80/20) fibre blend was miscible, and the FTIR spectra confirmed their functional groups. Therefore, the characterization results showed that the polymer blended solutions concentration and applied voltage increment affected fibre size distribution and morphology. Conclusion: Optimizing concentration and applied voltage successfully produced smooth, uniform bead-free zein/PVA fibre blends as parameters are increased.

Artificial Neural Network-Based Modeling of Performance Spark Ignition Engine Fuelled with Bioethanol and Gasoline

Machine learning technology can distinguish the relationship between engine characteristics and performances. Therefore, the goal of the present work is to predict the performance parameters of a single-cylinder 4-stroke gasoline engine at different ignition timings using a blended mixture of gasoline and bioethanol by an artificial neural network (ANN). Experimental data for training and testing in the proposed ANN was obtained at a dynamic speed and full load condition. An ANN model was developed based on standard Back-Propagation algorithm for the spark ignition engine. Multi-layer perception network (MLP) was used for non-linear mapping between the input and output parameters. An optimizer in the family of quasi-Newton methods (lbfgs) and the rectified linear unit function were used to assess the percentage error between the desired and the predicted values. The network input parameters are engine speed, fuel, and ignition timing. Furthermore, torque, power, specific fuel consumption (SFC), thermal efficiency (ηth), and energy consumption (EC) are taken as output parameters. The results show that ANN is the proper method for predicting SIE performance because it has accurate prediction results that are very similar to experimental results. Moreover, from the observation results, the ANN model can predict the engine performance quite well with correlation coefficient (R)=0.962139 and MSE=0.003967 for data testing.

Calcined Shale and Palm Oil Fuel Ash as Partial Replacements for Calcium-Based Binders to Enhance Compaction Properties of Marine Clay

ABSTRACT Marine clay is a problematic soil; therefore, its properties have been improved by mixing calcium-based binders, with reinforcing components. However, these materials exhibit many shortcomings, and better options are sought. Calcined shale (CS) is frequently used in concrete as a supplementary cementitious material, but it has not yet been used in soil stabilization. This study investigates the partial replacement of lime in marine clay treatment with CS and palm oil fuel ash (POFA). This study comprises two parts. In Part (1), POFA – lime-treated marine clay was assessed to determine the optimum proportion of POFA. In Part (2), CS – POFA – lime-treated marine clay was evaluated to determine the optimum ternary blending mixtures through many tests. Results of Part (1) indicate that the optimum proportion of POFA is 5%. In Part (2), CS exhibits effective enhancement in the properties of marine clay, and the optimum mixture was 10% CS, 5% POFA, and 3% lime. When lime content was reduced from 5% to 1% through replacement with CS, maximum dry density and optimum water content increased by 1.7% and 5.2%, respectively. Hence, CS can be effectively used as a partial replacement for lime in marine clay treatment.

Development of an atomistic model of cement-incorporated nano-red mud material

The complexity of the hydration process of cementitious materials makes developing universal models that predict their mechanical behavior challenging. The current study used a novel molecular modeling method to develop a bottom-up model of the cement paste that incorporated different contents of the nano-red mud (nRM). A molecular dynamics (MD) simulation and dreiding force field were employed to build the ingredient-based models using the cement clinker phases and nRM oxides. Different cement-nRM mixtures were prepared and macroscopically tested under compression and flexure. In addition, a detailed microstructural analysis using XRD, SEM, EDS, and Raman was carried out on the prepared of nRM. The experimental results were used to validate the results of the developed molecular models. The simulation results demonstrated the capability of the atomistic models for predicting the strength and stiffness of the cement-nRM composites accurately. In addition, the developed hydrated cement model was found with the line of C–S–H-mineral structure (called tobermorite 11 Å). The molecular characterization, in terms of the radial distribution function and fractional free volume, also provided useful information on the local structures of the models. The molecular models of cement-nRM can be further used to predict the durability properties as well as gain deep insights into the mechanical performance of blended mixtures.

Synthesis of 1-Hexanol/Hexyl hexanoate Mixtures from Grape Pomace: Insights on Diesel Engine Performances at High Bio-Blendstock Loadings

The production of oxygenated bio-additives for traditional fuels represents a key challenge due to their depletion in the near-future and their positive contribution to the reduction in environmental pollution. The present study considers the synthesis of 1-hexanol/hexyl hexanoate mixtures, two oxygenated Diesel bio-additives produced through the hydrogenation of hexanoic acid, obtainable from the fermentation of a wide variety of waste biomasses. In our case, crude hexanoic acid was produced through the fermentation of grape pomace, an abundant Italian agrifood waste. Commercial 5 wt% Re/γ-Al2O3 was adopted for the catalytic hydrogenation of crude hexanoic acid, and the support acidity allowed the tuning of the reaction selectivity toward the formation of hexyl hexanoate, instead of 1-hexanol, reaching yields of 40 and 25 mol%, respectively. The effects of each bio-additive on Diesel engine performance and exhaust emissions (soot, nitrogen oxides, carbon monoxide, unburned hydrocarbons) were evaluated, highlighting noteworthy positive effects especially on the reduction in carbon monoxide and soot emissions, if compared with those of Diesel fuel alone. Similar promising performances were achieved by employing Diesel blend mixtures of 1-hexanol/hexyl hexanoate, mimicking typical compositions of the rhenium-catalyzed post-hydrogenation mixtures. Even in such cases, 1-hexanol/hexyl hexanoate mixtures can be blended with commercial Diesel fuel, up to high loadings currently not yet investigated (20 vol%), without altering the engine performances and, again, significantly lowering soot and carbon monoxide emissions by more than 40%. This work highlights the possibility of obtaining such oxygenated bio-additives starting from waste through to a fully sustainable process and proves their beneficial effects on the reduction in exhaust emissions with no changes in engine performance.

Alkali activation of fly ash in self-consolidating concrete at low molar concentration

As a means of minimising the negative effects on the environment, the use of industrial byproducts in the building industry is becoming more popular. Recently, alkali activation of precursors has boomed in the market since activation of precursors improves mechanical properties and reduces the carbon footprint. However, one risk factor in alkali activation is molar concentration. This is because the increase in the molar concentration of sodium hydroxide/sodium silicate and the release of volatile substances from those acids is more harmful to the environment. Therefore, the present study investigates the activation of the precursor at low molar concentration, thereby equalising performance through the dosage of superplasticisers. In this regard, fly ash was activated at 5 M sodium hydroxide (NaOH) and replaced cement at varying percentages in the range of 0–30% by weight. The performance of self-consolidating concrete (SCC) was evaluated through fresh and hardened characteristics and microstructural analysis. The blended mixtures of SCC, activated fly ash (AFA) at 5 M sodium hydroxide, 0.89% of superplasticisers and 15% of replacement performed better than the control SCC. The outcome of the present study will provide a platform for activating a precursor at low molar concentration through the influence of superplasticisers.

Effect of Al2O3 content in slag on the relationship between slag reactivity and carbonation resistance

To understand the influence of slag chemistry on the carbonation resistance of slag-rich cement, this paper explored the carbonation characteristics of blended cement systems with different Al2O3 contents in slag through accelerated carbonation test. Irrespective of slag chemistry, three main CO2 binding phases were identified during accelerated carbonation test, i.e. carbonated Ca-Al AFm phases (amorphous or nano-crystalline), carbonated hydrotalcite-like phase, and calcium carbonate (amorphous calcium carbonate, vaterite, and calcite). Additionally, it was noted that the classification employed for slag reactivity (based on slag chemistry) cannot be extended to predict carbonation resistance of slag-rich cement directly. The main challenge occurred for slag with high alumina content. The experimental results showed that Al2O3-rich slag exhibited a high reactivity and can be considered as a reactive component in the blended mixture; however, it did not contribute to carbonation resistance of the mixture. Especially for CO2 binding capacity, it was similar for systems with varied alumina content in slag (from 3.69 to 18.19 wt.%) in the completely carbonated area.

Threading-the-Needle: Compatibilization of HDPE/iPP blends with butadiene-derived polyolefin block copolymers

Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene (iPP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE-iPP block copolymers (ca. 1 wt%) to mixtures of these polyolefins results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and iPP, where E and X are poly(ethylene-ran-ethylethylene) random copolymers with 6 wt% and 90 wt% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and iPP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topological entanglements of the amorphous X polymer and semicrystalline iPP, along with anchoring of the E blocks through cocrystallization with the PE homopolymer. Significantly, EXE can be inexpensively produced using currently practiced industrial scale polymerization methods, offering a practical approach to recycling the world's top two plastics.

Characterisation of alkali-activated stainless steel slag and blast-furnace slag cements

Rapid global industrial growth is causing an increase in the generation of large-scale by-products and waste materials, which can be recycled in the construction industry to decrease both the environmental impact of the sector and the impact of these waste materials, to ultimately contribute to the circular economy. In the current study, electric arc furnace stainless steel slag (EAFSS) as a potential precursor in the production of alkali activated materials (AAMs) is investigated, along and alternatively to the use of ground granulated blast-furnace slag (GGBFS). Five blended mixtures with different levels (0, 25, 50, 75 and 100 wt %) of EAFSS to replace GGBFS are activated with an alkaline silicate solution. Partially replacing GGBFS with EAFSS prolongs the dormant period in reaction and reduces the overall heat release of the paste mixtures. This results in a positive effect on fresh-state properties, increasing and prolonging workability and mixture setting times. A general decrease in strength is seen with EAFSS inclusion, although satisfactory compressive and flexural strength values of more than 85 and 9 MPa, respectively, were obtained at 28 days with up to 50% replacement of GGBFS by EAFSS. Most of the crystalline phases present within EAFSS do not participate notably in alkali-activation, other than merwinite which slowly dissolves and reacts to form a weak binder phase. The chromium present in the EAFSS is contained in a stable spinel phase; this element does not appear to be mobile in leaching tests.

Rate-based modeling and energy optimization of acid gas removal from natural gas stream using various amine solutions

Reduction in energy consumption of industrial plants is always an essential need due to high cost, CO2 emissions and global warming caused by energy supply from fossil fuels for boilers and electricity consumers. Iran has been struggling to compensate the lack of gas supply for domestic and industrial demands in winter within the past decade despite of having large natural gas resources. One of the most economical methods to decrease energy requirements in hydrocarbon plants is process improvement and revamping by changing existing solvents. There are already 44 identical acid gas removal units under operation in the South Pars Gas Complex (located in Iran) with the same feed composition. The gas-sweetening unit in the Phase 12, operating with the solution of 45.5 wt% methyldiethanolamine (MDEA), was modeled by Aspen Plus for acid gas removal (CO2 and H2S) as a rate-based model with the application of electrolyte non–random two–liquid (E-NRTL) activity model and Peng–Robinson equation of state in addition to the actual characteristics of the absorber and regenerator, and the operational conditions of the gas and liquid streams. After validation of the model by the real data from the plant, the incumbent amine solution was replaced with five proposed amine solutions – one single and four blended amine mixtures – in the same mass concentration to select the most efficient alternative from the aspects of outlet acid gas concentration, H2S content in the treated flash gas, required total power, reboiler power supply, and regeneration heat duty. The simulation results revealed that H2S was sharply absorbed on the top of the column, while CO2 was smoothly removed from the gas phase to the MDEA and blended solutions along the absorber and it occurred at the bottom of the column for the DEA solution. The blended amine solution of 1.5 wt% sulfolane + 44 wt% MDEA (Sulfinol-M) has shown to be the most appropriate option instead of the solution of MDEA compared to other suggested absorbents, with several advantages such as higher selectivity of H2S over CO2, low temperature bulge, highest H2S loading, and outlet sweet gas flow rate while required total power, reboiler power supply, and regeneration heat duty were reduced by 21.19%, 21.26%, and 23.54% respectively. The operational conditions of the unit with the application of the Sulfinol-M solution were optimized to achieve three specifications (constraints) and the minimum required total power (objective function) through a sensitivity analysis and optimization using a genetic algorithm to assure the reliability of values for three independent parameters, namely, amine solution temperature, amine solution flow rate, and gas temperature. The optimum limits and values of these parameters were 47–50 °C, 220 – 240 ton/h, and 34 °C respectively.

Chloride binding and diffusion of slag blended concrete mixtures

Ground granulated blast furnace slags (GGBFS/slag) can have a range of chemical compositions, especially in alumina content that could potentially affect several concrete properties including chloride binding capacity and chloride penetration. Chloride binding capacity and diffusivity of several cement-slag combinations were assessed using two slags of 8% and 17% alumina contents and four cements, ASTM C150 Type I, ASTM C150 Type I (high alkali), ASTM C150 Type II(MH) and ASTM C595 Type IL(14) at a cement replacement level of 60%. The findings indicate slag addition improved chloride binding and lowered chloride diffusivity. Between the two slags, chloride binding capacity was higher in high alumina slag. Type I cement mixtures had the highest binding capacity while it was the lowest in Type IL cement mixtures due to lower C3A, C3S and clinker factor. Chloride diffusivity experiments showed that plain Type IL mixture had the highest chloride ion penetration while it was the lowest when blended with high alumina slag due to carboaluminate formation. Therefore, chemical, mineralogical, and physical characteristics of cement-slag combination should be considered in service life analysis of slag blended concrete mixtures.

Combining the Classification and Pharmacophore Approaches to Understand Homogeneous Olfactory Perceptions at Peripheral Level: Focus on Two Aroma Mixtures.

The mechanisms involved in the homogeneous perception of odorant mixtures remain largely unknown. With the aim of enhancing knowledge about blending and masking mixture perceptions, we focused on structure-odor relationships by combining the classification and pharmacophore approaches. We built a dataset of about 5000 molecules and their related odors and reduced the multidimensional space defined by 1014 fingerprints representing the structures to a tridimensional 3D space using uniform manifold approximation and projection (UMAP). The self-organizing map (SOM) classification was then performed using the 3D coordinates in the UMAP space that defined specific clusters. We explored the allocating in these clusters of the components of two aroma mixtures: a blended mixture (red cordial (RC) mixture, 6 molecules) and a masking binary mixture (isoamyl acetate/whiskey-lactone [IA/WL]). Focusing on clusters containing the components of the mixtures, we looked at the odor notes carried by the molecules belonging to these clusters and also at their structural features by pharmacophore modeling (PHASE). The obtained pharmacophore models suggest that WL and IA could have a common binding site(s) at the peripheral level, but that would be excluded for the components of RC. In vitro experiments will soon be carried out to assess these hypotheses.

Monomer blended electrochemical polymerization in chiral liquid crystals to produce electro-optically active copolymer

Electro-optically active low-bandgap conjugated copolymers were obtained by electrochemical polymerization (EP) in cholesteric liquid crystal (CLC). We prepared CLC electrolyte mixture blends of monomers, and electrochemically polymerized for obtaining conjugated copolymer with optical activity, in which the structure of the CLC is transferred, from achiral monomers on a CLC template. In addition, this copolymer showed a narrow bandgap and a significant red shift of the absorption band compared to the homopolymer. The optical rotatory dispersion (ORD) indicates that the polymer is chiroptically active and that the optical rotation can be tuned via redox. The guest monomers used for the EP in liquid crystal (LC) require solubility in the host LC and a rod-like structure, limiting their structural design. This technique has the advantage that complex synthesis of monomers is no required, and simple composition of monomers can be used to prepare copolymer films in a convenient manner by blending various monomers. This method expands the design range of optically active electrochromic devices based on conjugated polymers with pleochroic properties.

Utilising Pareto efficiency and RSM to adjust binder content in clay stabilisation for Yttre Ringvägen, Malmö

In this paper, we present a new framework for improving soil strength using an advanced method of engineering statistics. The materials included clay till collected in Yttre Ringvägen, southern Sweden. Binders included quicklime, slag and ordinary Portland cement used as pure binders and blended mixtures. We first applied the Response Surface Methodology techniques aimed at binder blend optimisation: 1) Central Composite Design; 2) Box-Behnken Design; 3) Simplex Lattice Design. The Pareto charts were presented for modelling responses from tests with different binders and estimating their effects on soil strength. Finally, to examine the variables important for soil stabilisation, we also evaluated the effect of the amount of binder and the interaction between cement/lime/slag in different ratios: 30-50-20 %; 50-50-0 %; 100-0-0 % The paper highlights the major opportunities and challenges of engineering statistics as a cross-cutting research direction for the issues of civil engineering.

Effect of synthesized lemongrass biodiesel on the performance and emission characteristics of a CI engine

Present work covers the preparation of biodiesel (BD) from lemongrass oil through transesterification process followed by their characterization, performance, and emission study in term of blending mixture (BM) with fossil diesel (FD). Analytical study FTIR, H NMR and GC–MS confirms prepared BD properties is similar to FD. Seven BM composed of BD and FD named as, BM5, BM10, BM15, BM20, BM25, BM30 & BM40 contains 5, 10, 15, 20, 25, 30 & 40 % (vol.) of BD respectively. Prepared BM has been tested in gas analyzer integrated 4-Stroke, single cylinder vertical cooled self- governed diesel engine and compared their result based on FD performance. Performance results indicates BSFC & EGT for BM20 increases by 48% & 4.08% and BTE decreases by 14.75 % in comparison with FD. Emission study reflects decrement in HC by 49.99 %, decrement in CO by 46.80 %, increment in CO2 by 3.23 % and increment in O2 by 28.57 % in exhaust gas for BM20. Overall emission results indicate their best result for BM containing 20 % BD and its addition in FD can play an important role as an alternative of fossil fuel.

Density and Strength Performance of Cellular Concrete Blended with Bentonite Clay and Polypropylene Fiber

Cellular concrete (known as foamed concrete) is a lightweight building material with low densities ranging from 900 kg/m3 to 1900 kg/m3, which can have potential applications in civil engineering practices. However, it is very weak in withstanding tensile loads which leads to cracks during shrinkage in the drying stage. Therefore, six different groups of cellular concrete are prepared for a possible application in grouting underneath the foundations to achieve a minimum compressive strength of 2000 psi (13.79 MPa) as per ASTM C476, and for soil nail grout with a minimum compressive strength of 3000 psi (20.86 MPa) as per ASTM C109 at 28 days. Furthermore, these mixtures are undergoing laboratory testing for pushout (using steel cylinders with varied diamters and thickneses) and pullout tests as the subsequent part of this project. All groups contain 0.34 water-to-cement ratio, same size and amounts of sands and superplasticizer (SP). The first group included four control mixes without bentonite and polypropylene fiber (PPF) additives with varied foam content (C1-F1,F2,F3,F4). The remaining groups consist of 17 different mixes blended with either one or both additives. The content effect of foam agent, bentonite clay, and PPF as additives on the density and compressive and flexural strengths of cellular concrete are investigated in this study. The results revealed that the introduction of bentonite and/or PPF in cellular concrete mixtures increased the density and strength. The results revealed that low dry densities (less than 1900 kg/m3) of blended cellular concrete mixtures can reach high compressive strength of 24.37 MPa with 4.74 MPa flexural strength that make them feasible for geotechnical and structural engineering applications.

Fabrication and characterization of ZrO2 reinforced Fe-20Cr alloy composites

The reinforcement effects of the ZrO2 and the wear and mechanical behaviour of (Fe,Cr)-based alloy composites were investigated. The (100−x) (Fe80Cr20) -(x) ZrO2 composites were fabricated via powder metallurgy. The iron-chromium and ZrO2 powders were efficiently milled and mixed in ball mill. In the Fe80Cr20 alloy, the effect was investigated by changing the ZrO2 composition by 5%, 10%, and 15%. The blended powder mixture was cold compacted and sintered at 1030 °C. Scanning electron microscopy (SEM), elemental mapping, and x-ray diffraction techniques were utilized to assess the microstructural properties of the sintered composites. In addition, the mechanical properties such as hardness, flexural strength, and porosity were examined with variations in ZrO2 composites. The dry sliding wear tests with various normal loads and a constant sliding distance were used to find the composite’s wear behaviour. The composite containing 10% ZrO2 has shown the maximum flexural strength with 1470 MPa, and hardness 359.8 HV10 respectively, compared to 5% ZrO2 and 15% ZrO2. With a concentration of 10 wt.% ZrO2, the wear resistance is found to be significantly enhanced, while after 10 wt.% ZrO2, its properties deteriorate. In addition to having improved interfacial bonding, lower porosity, and microstructure uniformity, Fe80Cr20 (Fe-20 Cr) −10 wt% ZrO2 composites exhibit superior mechanical properties compared to other materials.