Advanced Materials Research Vol. 1168

Abstract: The loess produced in South Korea is an eco-friendly material with high gas adsorption performance. Korean loess, however, cannot be used as a structural material because it has a very low compressive strength compared to cement. However, even if it is recommended as an interior material, its large drying shrinkage during drying disturbs wet construction. Therefore, this study aimed to develop a method to reduce the amount of water added while maintaining the consistency required for the plastering work of Korean loess. The experimental results showed that the dispersion of clay particles was improved when Na+ and K+, which are monovalent cations, were added to the loess colloid; the reverse occurred, i.e., aggregation of clay particles, when Ca2+ and Mg2+, which are divalent cations, were added. In addition, the dispersion and aggregation of clay particles affect the consistency of loess. The dispersion allows the loess paste to obtain the required consistency using less water, but the aggregation may exhibit the opposite effect. Accordingly, based on the same consistency, the specimens with less water exhibited less drying shrinkage. The drying shrinkage decreased by 9.23% for the specimen fabricated with the 0.01 M Na2SiO3 aqueous solution.

Abstract: Concrete is very strong in compression but weak in tension. It is therefore reinforced with steel reinforcement to carry the tensile stresses. The use of steel reinforcement in concrete is expensive, and calls for investigation on other materials that are cheap in order to reduce the cost. Due to these reasons, a study has been made with the objective of determining the suitability of areca palm fibers in reinforcing concrete for improving its properties at fresh and hardened states. The sampled areca palm fibers were treated by using 5% by weight of NaOH solution. Experiments were conducted on concrete grade C25 with addition of fibers in five mix proportions of 0.1%, 0.3%, 0.5%, 0.7% and 0.9% by weight of cement. The results showed that the workability of concrete with fibers is lesser than that of conventional concrete. Also, the modulus of elasticity and compressive strength increased to an optimum weight fraction of 0.7% beyond which they started to decrease. The ability to resist cracking and spalling were also enhanced. The study found that the optimum fibers content was 0.7% by the weight of the cement and that areca palm fibers can be used to improve the engineering properties of concrete. Keywords: Areca fibers, concrete, workability, compressive strength, tensile strength, modulus of elasticity

Abstract: The aim of this work is a development and characterization of a sustainable product from solid waste from civil construction. Morphology of collected waste has been analyzed by SEM/EDS. Residues have been macerated, mixed in different proportions with cement and water, and made into rectangular boxes. Mechanical test has been carried out by flexing three points on specimens, absorbing water and analyzing fracture by SEM. Morphology of samples have shown a heterogeneous and porous mass, with particles of different sizes, few agglomerates, and presence of organic material. Resistance to average rupture of samples has been obtained in MPa, characteristic of concrete for structural application. For CDR to be used in sustainable ceramics, it is recommended to improve a process of comminution and homogenization to guarantee reproducibility of lots and technological product properties. This being so, a mockup has been developed proposing a hollow element type product, Cobogó style, indicating potential of using civil construction waste as a sustainable product.

Abstract: The development of platinum-free counter electrodes (CEs) is significant in the development of cost-effective dye-sensitized solar cells (DSSCs). In this study, Pt-free, low-cost carbon black-titanium nitrate (CB-TiN) nanocomposite counter electrodes CEs were prepared via simple heating and cooling process for application in DSSCs. Different weight concentrations of CB-TiN (15-200 mg) were uniformly blended with PEDOT:PSS at 350 rpm and 150°C for 10 mins. Thereafter, the solution mixtures were immediately cooled at 4°C overnight to produce PEDOT:PSS/CB-TiN CEs. Further, to investigate the effects of iso-octyphenoxy-polyethoxyethanol (TX100) on the performance of the PEDOT:PSS/CB-TIN CE, various concentrations of TX100 (1-10%) were blended with PEDOT:PSS/15mgCB-TiN CE mixture at room temperature to produce PEDOT:PSS/15mgCB-TiN/TX100 CEs. The results indicated a gradual increase in electrocatalytic activity coupled with a reduction in internal resistance in the DSSCs as the weight of CB-TiN nanoparticles was enhanced. Similar results were obtained when the concentration of TX100 was increased. The DSSCs with the PEDOT:PSS/200mgCB-TiN and PEDOT:PSS/15mgCB-TiN/10%TX100 CEs exhibited optimum performances of 4.42% and 4.32%, respectively. Their performance closely matches that of the Pt CE (4.43%).

Abstract: The effect of fiber cross-section on effective elastic and piezoelectric coefficients of piezoelectric fiber reinforced composites (PFRC) is investigated through two micromechanical analyzes viz. modified strength of materials (MSM) approach and energy approach. Results are verified with that of strength of materials (SM) approach available in the literature. A constant electric field is considered in the direction transverse to the fiber direction and is assumed to be same both in the fiber and matrix phases. It is observed that MSM and strength of materials (SM) approach predictions for the effective piezoelectric coefficient of the PFRC assessing the actuating capability in the fiber direction are in excellent agreement and also when the fiber volume fraction exceeds a critical value, this effective piezoelectric coefficient becomes significantly larger than the corresponding coefficient of the piezoelectric material of the fiber as investigated by both SM and MSM approaches. However, results of energy approach differ from both MSM and SM results and effective piezoelectric constant never exceeds to that of fiber as obtained by energy approach. It has been found for the piezoelectric fibers, cross-section of fiber has insignificant effect on the effective properties as predicted by MSM and energy approaches. Nomenclature

Abstract: This paper proposes a deep learning model for predicting the durability benchmark on concrete specimens. The durability benchmark on concrete samples is commonly estimated throughout the Ultrasonic Pulse Velocity measurements. This test establishes a relationship with concrete durability taken into consideration the material's homogeneity. The model proposed in this paper is feed by standard laboratory tests as input parameters, making the model a practical and efficient alternative to predict durability concrete benchmark, saving time, short-cut laboratory work, and avoiding sophisticated instrumentation use. Furthermore, it is an attractive alternative to the need for sophisticated instrumentation for estimating the Ultrasonic Pulse Velocity. The outcomes depict a high predictive accuracy about of 96% in the validation stage. In addition, the model was tested by a new dataset with different properties to demonstrate robustness and certainty in the model. Finally, the model achieves an impressive accuracy of 95.89% in the new validation dataset.

Abstract: An eco-friendly and low cost modified mixture of both Wild Carob and Cupressus sempervirens with H₃PO₄ (Cupcar-H₃PO₄) was prepared to extract a cationic dye (Crystal Violet) from an aqueous solution in a batch reactor at the laboratory of chemical engineering, Department of Process Engineering, Faculty of Technology, Farhat Abbas Setif University-1. The pH effect, contact time, initial concentration of dye, ionic strength and temperature were investigated in this study. The Maximum adsorption capacity was found to be 117.26 mg/g at 25°C for a natural pH (ph =6.22). The active functional groups of Cupcar-H₃PO₄. These peak shifts indicated that especially the bonded –OH groups, C–O stretching of ether groups, and C=C group played a major role in CV adsorption onto Cupcar-H₃PO₄. The new bands of low intensity which appeared at 890 cm⁻¹ and 813 cm^-1 after CV adsorption and which could be attributed to a υ (CV-biosorbent) constituted the most striking result. Kinetics of biosorption of crystal violet (CV) was analyzed and the results showed that both pseudo order (PSO) and the pseud nth-order model (PNO) models gave most accurate fit than the pseudo-first-order model (PFO). Isotherm data were analyzed by four classical models, Langmuir and Freundlich with two parameters, Sips and Redlich-Peterson with three parameters. And for more information on the mechanism of CV uptake on the Cupcar-H₃PO₄ material, three advanced models are applied to isothermal data, Monolayer with one energy (M1), Monolayer with two energies (M2), and Double layer with one energy (M3). For the classical models and in the case of the two parameters models the Langmuir one gives a better fit for the data isotherm according to the R². In the case of three parameters models, both Sips and Redlich-Peterson accurately described experimental data. Monolayer with two energy sites model (M2) was shown to be the most appropriate advanced statistical physics model for fitting CV biosorption onto the Cupcar-H₃PO₄ biosorbent, this model suggested that the CV pollutant was adsorbed at two different Cupcar-H₃PO₄ biosorbent sites, and that a variable number of CV molecules could be adsorbed at each site; from this, the CV dye was adsorbed with 2 different adsorption energies. The changes in the enthalpy, the standard free energy and the entropy were also evaluated and the reaction was found to be spontaneous, endothermic and physical in nature.

Abstract: As a non-destructive evaluation method for friction stir welded joints, this research aims to develop and corroborate a method for material flow analysis and defect detection based on X-ray computed tomography (X-ray CT). Using a cylindrical FSW tool with a broad shoulder, joints of dissimilar materials AA6061-T6/AZ31b are friction welded employing tool rotary speed ranging from 1000 to 1500 RPM and tool feed from 125 to 400 mm/min. The welded joints are scanned via X-Ray CT with an image bit depth of 16-bit then segmented based on the Hounsfield Units scale (HU) and the global Otsu thresholding method. This segmentation divides the DICOM images into masks for each different material, from which 3D renderings are generated to record volumetric data. For analyzing elemental mixing, measurements of material penetration and transfer are carried out. Corroborating these results was accomplished using destructive cross-sectioning and Energy Dispersive X-ray Spectroscopy (EDX). The results show that this method can detect internal defects and characterize the material mixing with results comparable to that of destructive EDX analysis. The effect of improving scan resolution on reconstructed images was shown to slightly improve the accuracy of the thresholding method while reducing the standard deviation of segmented material ranges.

Abstract: In stilling basins there is a change in flow regime from supercritical to subcritical flow; this transition is called a hydraulic jump. To control and stabilize the position of the jump, it is necessary to place a sill across the flow. A bibliographical analysis showed that when the controlled hydraulic jump is entirely formed upstream of the stilling basin, the sill has no effect on the configuration of the jump. However, when the jump length stretches beyond the sill position, this results in jump compactness and leads to several configurations of the latter, until it completely disappears. The main objective of this study is to determine the effect of the hydraulic jump compactness on the main jump features in a trapezoidal horizontal channel. Dimensionless empirical relationships depending on the jump compactness are obtained. Through this study, we aim to show the advantages of the jump compactness on the channel dimension. Indeed, the hydraulic jump is led to its most reduced form, before disappearing, in terms of tail water depth and jump length. Thus, the obtained results are useful for dimensioning the stilling basin.

Abstract: During a world-wide pandemic solutions for the production of anti-viral products is an at all-time high, motivating research into a wide array of potential solutions, with special interest to those capable of being deployed with as close to zero alterations to the production methods. The present work investigates the potential of using two additives, a commercially available masterbatch and a copper oxide powder, compounded using LDPE as a matrix, to be incorporated in a standard industrial setting. The final products were conventional polyester-based TNTs with 5 g m^-2 coatings obtained from the micronized LDPE compounds. Antimicrobial and antiviral properties were evaluated for the two TNT products, revealing both solutions as technical equivalents and capable solutions for the production of PPEs.