2020-08-09
Nunes, Vanja Fontenele, Andrade, Carla Freitas de, Freire, Francisco Nivaldo Aguiar, Sombra, Antonio Sérgio Bezerra
Nunes, Vanja Fontenele ; Andrade, Carla Freitas De ; Freire, Francisco Nivaldo Aguiar ; Sombra, Antonio Sérgio Bezerra ; ABSTRACT Dye sensitized solar cells (DSSC) are a third-generation solar cell, composed of dye, photoanode, a counter electrode and a redox electrolyte. The sensitized dye affects the overall efficiency of the cell by the amount of excited dye inside the cell. This work investigated the effect that different time’s absorption of N719 dye causes on a TiO2/ZnO based DSSC. The longer dye sensitized time helped to increase the short-circuit current density and the efficiency of the cell, with optimum time of six hours, for current and four hours for efficiency.
2020-08-09
Li, Xiaohui, Pan, Yi, Guo, Mingzhe
Li, Xiaohui ; Pan, Yi ; Guo, Mingzhe ; ABSTRACT Conventional calcium bentonite suffers from poor rheological properties and poor static stability.To address these challenges, this study developed a novel sodium-activated bentonite composite modified with natural citrus pectin (CP) through chemical intercalation, termed Na-BT-CP. Under optimized conditions (0.8 wt% CP), the composite demonstrated a synergistic enhancement in rheological properties at 80°C, with a 44% increase in apparent viscosity and a remarkable 175% surge in the yield point-to-plastic viscosity ratio (YP/PV). The material exhibited exceptional thermal stability, maintaining viscosity fluctuations below 1.3% within the 25–100°C range, and outstanding static stability with less than 2.6% performance attenuation after 24 hours. XRD and FT-IR analyses confirmed the successful intercalation of CP into the bentonite interlayers, forming a synergistic bonding network via Na+ bridging and hydrogen bonding. This work provides a new pathway for developing high-performance, environmentally friendly drilling fluid materials using renewable resources.
2020-08-09
Alagarsamy, Ramya, Ganesan, Lavanya
Alagarsamy, Ramya ; Ganesan, Lavanya ; ABSTRACT This research aims to explore the mechanical and durability properties of geopolymer concrete (GPC) with varying content of fly ash, Ground Granulated Blast Furnace Slag (GGBS), biochar, and nano-cellulose fibres under different curing conditions. GPC, compared to traditional concrete, showed superior strength properties, particularly in mixture containing optimized GGBS and biochar. The maximum 28 day compressive strength of 61.12 MPa was recorded in the mixture containing 22% fly ash, 72% GGBS, 6% biochar, and 0.6% nano-cellulose fibres. The mixture also exhibited good workability and enhanced tensile and flexural strengths. Tests of durability such as Rapid Chloride Permeability Test (RCPT), acid and sulphate resistance, and carbonation depth indicated that additions of biochar and nano-fibres greatly alleviated permeability and strength loss. Nano-cellulose fibres have also improved matrix compaction, minimizing carbonation depth and enhancing durability in aggressive exposures. ANOVA has ensured that there were significant workability and compressive strength differences, whereas RCPT differences were statistically insignificant, indicating time-dependent variability in chloride resistance. In general, the incorporation of biochar and nano-cellulose fibres into GGBS rich GPC enhances mechanical strength and durability, justifying its viability as a green replacement for ordinary Portland cement (OPC) for long-term infrastructure construction under extreme environmental conditions.
2020-08-09
Krishnaswami, Nirmal Kumar, Chinnusamy, Manoj Prabhu, Annamalai, Sivakumar, Thirumoorthy, Pradeep
Krishnaswami, Nirmal Kumar ; Chinnusamy, Manoj Prabhu ; Annamalai, Sivakumar ; Thirumoorthy, Pradeep ; ABSTRACT The practice of disposing of incinerated bottom ash (IBA) in landfills impose serious risk over the environment. Perhaps, the lack of fine aggregates in the building sector emphasize the use of appropriate substitutes made from industrial wastes. The potential use of treated IBA as a fine aggregate alternative in concrete is examined in this study. By varying the IBA replacement ratios and at constant w/c ratio, the impact of IBA was examined. The concrete mixes were made at 0.45 w/c ratio, and the fine aggregate was replaced with 0% to 100% IBA at 30% intervals. The physical and chemical tests of the IBA verified the presence of heavy metals and found that the concentrations were within acceptable constraints. The workability of the concrete mixes containing IBA was assessed, and the concrete properties were measured using water absorption at 7, 28, 56, and 90 days as well as compressive, flexural, and elastic modulus strength at 7, 14, 28, and 56 days. The findings show that substitution of higher proportions of IBA have an impact on workability and show decreased strength with increased water absorption properties. On the other hand, concrete characteristics at all replacement levels tend to improve with increased curing. The TGA investigation reveals the incidence of fewer Ca(OH)2 peaks due to the incomplete dilution of cement matrix, whereas SEM microstructural studies show dense structure with fine aggregates and porous structure with IBA.
2020-08-09
Bunpheng, Wasurat, Varudharajan, Gopinath, Muthaiah, Vadivel Muthurathinam Rajavel, Dhairiyasamy, Ratchagaraja, Singh, Subhav, Chan, Choon Kit
Bunpheng, Wasurat ; Varudharajan, Gopinath ; Muthaiah, Vadivel Muthurathinam Rajavel ; Dhairiyasamy, Ratchagaraja ; Singh, Subhav ; Chan, Choon Kit ; ABSTRACT Aluminum–boron carbide (Al–B4C) composites have shown promise as lightweight, wear-resistant materials; however, weak particle–matrix bonding, melt-stage clustering, and unstable friction have limited reliability. Addressing these linked defects is essential for high-strength components. Prior work did not vary the interface design, dispersion, and solid lubrication simultaneously within a single process history, leaving the synergy untested. This study aimed to determine whether engineered interphases produced by ultrasonic dispersion and trace 2D lubricants increased the tensile strength and stabilised sliding wear. A balanced factorial crossed interphase route (electroless Ni–P, sol-gel TiO2→TiC, in situ Ti/B), ultrasonication on/off, and graphene or hBN at 0–1.0 wt. %; XRD/EDS, interphase-thickness and dispersion statistics, and quantitative masks for pull-out and tribofilms supported the analysis. Tensile and pin-on-disk tests yielded wear, friction, and UTS. Graphene-bearing hybrids with Ni–P or in-situ Ti/B maintained UTS ≥330 MPa and reduced wear to ≤0.2 mm3·m−1 with steady friction near 0.20; transfer films reached 65–80% coverage and 95–105 nm median thickness. Ultrasonics sharpened the TiC interfacial coherence and reduced particle pull-out. The results indicated that metallurgical or ceramic interphases paired with graphene produced a low-wear, high energy efficiency on the strength–wear map and surpassed states.
2020-08-09
Krishnasamy, Boopathy, Gladston, Allwyn Kingsly, Sekar, Chandragiri Baskar, Selvaraju, Mayakannan
Krishnasamy, Boopathy ; Gladston, Allwyn Kingsly ; Sekar, Chandragiri Baskar ; Selvaraju, Mayakannan ; ABSTRACT Natural fibers are gaining significant research attention due to their ecological, renewable, and environmentally friendly nature, making them attractive alternatives to synthetic reinforcements. This experimental study investigates the thermo-mechanical behavior of Peepal fiber (PF) reinforced epoxy composites modified with Ziziphus mauritiana seed powder (ZMSP). Hybrid composites were fabricated by maintaining a fixed fiber weight fraction of 40% PF, while varying the particle content at 3, 6, 9, and 12 wt%. Prior to incorporation, the particles were chemically treated with 5% NaOH and characterized using FTIR, XRD, and TGA analyses. The treatment increased crystallinity index, enhanced thermal stability, and promoted better interfacial adhesion with the matrix. Mechanical tests revealed that composites with 3 wt% filler displayed the highest impact strength, whereas 9 wt% filler exhibited optimum tensile, compressive, flexural, hardness, and fracture toughness properties. Thermogravimetric analysis confirmed enhanced thermal resistance, while water absorption and biodegradability increased with particle loading. SEM micrographs illustrated improved fiber–matrix interaction and reduced void formation at optimal filler content. The combined improvements in strength, toughness, and stability demonstrate that PF–ZMSP hybrid composites can serve as sustainable, cost-effective, and lightweight materials suitable for moderate load-bearing applications in automotive, structural, and industrial sectors.
2020-08-09
Tejaswini, Nandipati, Sreenivasulu, Anduri, Rao, Boddepalli Krishna
Tejaswini, Nandipati ; Sreenivasulu, Anduri ; Rao, Boddepalli Krishna ; ABSTRACT This research investigates the influence of quartz sand and alccofine on the mechanical and durability performance of concrete. Quartz sand was used to replace natural fine aggregate in various percentages (0%, 25%, 50%, 75%, and 100%), while alccofine was added as a replacement to cement by 10%. The experimental plan consisted of testing for compressive, split tensile, and flexural strength and durability tests under hydrochloric acid and sulfuric acid exposure. The test results indicated that mix AQ25, consisting of 25% quartz sand and 10% alccofine, was the best performing mix, with a 28-day compressive strength of 61.27 MPa, which is an increase of 38% over conventional concrete. Mix AQ25 also resulted in higher values of split tensile (3.52 MPa) and flexural strength (6.3 MPa), reflecting improved characteristics of ITZ. Tests for acid resistance also demonstrated a higher residual strength and less deterioration for quartz sand-based mixes, with AQ25 maintaining strengths of 59.55 MPa after 1% HCl and 53.25 MPa after 1% H2SO4 attack. SEM observations also showed improved microstructural density, superior formation of C-S-H gel, and reduced porosity for optimized mixes. In general, the blending of alccofine with 25% quartz sand increases the strength and durability of concrete considerably.
2020-08-09
Vedanayagam, Murugesh, Ramharrack, Varsha, Veettil, Leena Aroli, Abraham, Susan, Dhamodharan, Maruthachalam, Palanisamy, Sasikumar
Vedanayagam, Murugesh ; Ramharrack, Varsha ; Veettil, Leena Aroli ; Abraham, Susan ; Dhamodharan, Maruthachalam ; Palanisamy, Sasikumar ; ABSTRACT Artificial Neural Networks (ANNs) offer a compelling alternative, yet they rely significantly on varied and high-quality datasets. The scarcity of experimental data, particularly for fibre-reinforced High-Strength Concrete (HSC), limits the generalization and dependability of models. Therefore, the key challenge lies in creating resilient ANN architectures capable of accurately predicting various mechanical properties of HSC. This study develops an ANN model in MATLAB to predict the mechanical properties of HSC using input parameters such as cement, aggregates, mineral admixtures, chemical admixtures, steel fibres, glass fibres, and water. Seventy-two experimental results were employed for training and testing, and the model’s predictions were validated against experimental data. The ANN demonstrated high accuracy in estimating compressive strength, split tensile strength, and flexural strength of HSC with varying fibre contents and water–cement ratios. Strong agreement was observed between predicted and experimental values, with coefficients of determination (R2) of 0.98 for compressive strength, 0.93 for split tensile strength, and 0.93 for flexural strength. These findings highlight the potential of ANN-based approaches as reliable tools for modelling and predicting the mechanical performance of high-strength concrete.
2020-08-09
Shanmugam, Bharani, Anwar, Gulshantaj Mohammed Nabi, Ramu, Muthuminal
Shanmugam, Bharani ; Anwar, Gulshantaj Mohammed Nabi ; Ramu, Muthuminal ; VISUAL ABSTRACT
2020-08-09
Li, Haijia, Chen, Ye, Yang, Xiang, Wang, Jiangqing, Zhang, Qinglian
Li, Haijia ; Chen, Ye ; Yang, Xiang ; Wang, Jiangqing ; Zhang, Qinglian ; ABSTRACT This study explores the use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the direct quantification of cadmium in human hair, addressing the demand for rapid, spatially resolved, and minimally destructive biomonitoring methods. Cadmium, a toxic heavy metal associated with renal and metabolic disorders, is typically measured using techniques that require extensive sample preparation, potentially compromising temporal and spatial exposure data. This work fills the gap in validated LA-ICP-MS hair analysis protocols by implementing matrix-matched calibration and validating the method against solution nebulization ICP-MS. The aim was to develop a robust, high-resolution technique capable of accurately quantifying cadmium across a broad concentration range. Calibration curves were prepared using certified reference materials, and method performance was evaluated through precision, accuracy, reproducibility, and depth-profile analysis. The method showed excellent linearity (R2 > 0.999), with cadmium levels in environmentally exposed individuals exceeding EPA thresholds by up to 1100%, indicating elevated renal toxicity risk. Spatial mapping revealed distinct cadmium peaks linked to occupational and environmental exposure events, while zinc and sulfur served as stable internal standards, enhancing reliability. These results position LA-ICP-MS as a powerful alternative to conventional methods, with future work focusing on population studies, and isotopic tracing for source attribution.
2020-08-09
Battina, Swathi, Darapaneni, Chandra Mouli, Tanimki, Chandra Sekhar Rao
Battina, Swathi ; Darapaneni, Chandra Mouli ; Tanimki, Chandra Sekhar Rao ; ABSTRACT In this paper, a study has been made to understand the strength and behavior of fabricated Ferro cement elements under four-point bending. The size of the element adopted in this study is 800 mm × 150 mm × 50 mm. A mortar mix 1:1.1 by weight with w/c ratio 0.36 was adopted. Variables of the study include the number of layers of wire mesh. The number of mesh layers varied is 0, 3, 4, 5 and 6. From the test results it was observed that both first crack and ultimate moments were increased with the increase in volume fraction of reinforcement. It was also observed that the crack width is efficiently controlled by the higher volume fraction of mesh reinforcement. The ultimate moment capacity of the Ferro cement elements are calculated by two methods. The first method is based on the concept of conventional reinforced concrete theory and second method is based on the concept of plastic analysis. A comparison of the ultimate moments predicted from elastic and plastic analysis theories with experimental data shows good agreement.
2020-08-09
Arumugam, Sujitha, Ravichandran, Panruti Thangaraj, Ramachandran, Ramasubramani
Arumugam, Sujitha ; Ravichandran, Panruti Thangaraj ; Ramachandran, Ramasubramani ; ABSTRACT This study investigates the use of Recycled Coarse Aggregates (RCA) as a partial or full replacement for Natural Aggregates (NA) in structural concrete, addressing the rising Construction and Demolition (C&D) waste in India. Although environmentally beneficial, RCA use in structural applications is limited due to concerns over strength and durability. To assess its feasibility, bond strength between RCA concrete and steel reinforcement was tested using the RILEM pull-out method and simulated in ANSYS Workbench. Non-Destructive Testing (NDT), particularly Ultrasonic Pulse Velocity (UPV), was used to evaluate compressive strength, dynamic elastic modulus, and durability indicators. Results showed that M30 concrete with 25% RCA outperformed conventional concrete in strength. A 2.3% reduction in bond strength was observed with 16 mm bars, while 100% RCA with 20 mm bars showed a 1.25% improvement. In M50 concrete, up to 50% RCA retained adequate strength, with bond performance influenced by bar diameter. The dynamic elastic modulus was 48% higher than the static value. Acid exposure caused visible surface deterioration, indicating possible durability concerns. Overall, RCA can be effectively used in structural concrete with proper design and quality control. The study also emphasizes the relevance of NDT methods in assessing the performance of RCA concrete.
2020-08-09
Sankarasabapathi, Sankarapandian, Velmurugan, Santhosh, Devaraj, Jebakani, Karpagavinayagam, Essakiappan Karthik
Sankarasabapathi, Sankarapandian ; Velmurugan, Santhosh ; Devaraj, Jebakani ; Karpagavinayagam, Essakiappan Karthik ; ABSTRACT Biodegradable polymers reinforced with natural fillers are increasingly explored as sustainable alternatives to petroleum-based plastics for packaging applications. In this study, banana leaf powder (BLP), an abundant agricultural waste, was used as a reinforcement for polylactic acid (PLA) to fabricate biocomposite films via a solvent casting technique. BLP was incorporated at 0, 5, 10, 15, and 20 wt.%, and the resulting films were characterized for their mechanical, thermal, morphological, and water absorption properties. Fourier transform infrared spectroscopy (FTIR) revealed enhanced hydrogen bonding between the hydroxyl groups of BLP and the ester groups of PLA. Tensile testing (n = 5) showed that the 15 wt.% BLP/PLA composite achieved the highest tensile strength (71.5 ± 1.8 MPa) and elongation at break (8.1 ± 0.4%), representing an improvement of approximately 22% and 224%, respectively, compared to neat PLA. Thermogravimetric analysis indicated improved thermal stability, with the onset degradation temperature increasing from 290 °C for neat PLA to 325 °C for the 15 wt.% BLP composite. SEM analysis confirmed uniform filler dispersion at moderate BLP loadings, while higher contents led to particle agglomeration. Water absorption increased with BLP content due to the hydrophilic nature of the filler. Overall, the results demonstrate that BLP is an effective, low-cost, and sustainable reinforcement for PLA, with 15 wt.% BLP providing an optimal balance between mechanical performance and thermal stability for sustainable packaging applications.
2020-08-09
Subramani, Jeevitha, Venkataraman, Gayathri
Subramani, Jeevitha ; Venkataraman, Gayathri ; ABSTRACT With the increasing demand for sustainable building materials, researchers have developed geopolymer-based tiles using bauxite residue (BR) and other industrial by-products. This approach supports the zero-waste concept by converting waste from alumina refineries, steel plants, and coal-fired power stations into value-added products. The primary constituents include BR, ground granulated blast furnace slag (GGBS), and fly ash (FA), while manufactured sand (MS) and quarry chips (QC) were used as fillers. A small I-Crete (IC) dosage was incorporated as an admixture to improve overall performance. BR exhibits moderate reactivity compared to conventional binders, and its influence was studied at different replacement levels. The optimum mix was 30% BR, 20% GGBS, and 50% FA, with a filler-to-binder ratio of 1:1.5 and 2% I-Crete (R30G20F50I02). Sodium silicate and sodium hydroxide with 4M concentration were alkaline activators. After 28 days of curing, the developed tiles showed excellent flatness (0.6 mm), perpendicularity (<1%), straightness (<0.8%), wet transverse strength of 6.285 N/mm2, wear resistance of 3.26 mm, and water absorption of 5.59%. All properties satisfied IS 13801-2013 standards, making the tiles suitable for outdoor flooring such as walkways, patios, warehouses, and factory surfaces.
2020-08-09
Chileno, Nahúm Gamalier Cayo, Alviano, Daniela Sales, Rocha, Joaquin Humberto Aquino, Rosas, Marialaura Herrera, Gomes, Otavio da Fonseca Martins, Rezende, Fernando Henrique Guimarães, Mesquita Júnior, Laércio, Silva, Gabrielle Avelar, Ferreira, Maria Alves, Ferreira, Saulo Rocha, Toledo Filho, Romildo Dias
Chileno, Nahúm Gamalier Cayo ; Alviano, Daniela Sales ; Rocha, Joaquin Humberto Aquino ; Rosas, marialaura Herrera ; Gomes, Otavio Da Fonseca Martins ; Rezende, Fernando Henrique Guimarães ; Mesquita Júnior, Laércio ; Silva, Gabrielle Avelar ; Ferreira, Maria Alves ; Ferreira, Saulo Rocha ; Toledo Filho, Romildo Dias ; ABSTRACT This study investigates the limitations of biomineralization for the surface treatment of cracks in cement pastes. The proposed strategy involves the application of Pythium aphanidermatum spores on pre-carbonated cement matrices with induced cracks. The pastes were reinforced with polypropylene fibers, cracked via diametral compression, and subsequently subjected to a controlled carbonation process. Three treatment conditions were evaluated: water (Ref) and two biological solutions (T1 and T2) containing calcium acetate, Potato Dextrose Broth (PDB), and Pythium spores; T2 also included urea as an additional nutrient source. Treatment performance was assessed through load recovery and crack width closure. Additionally, SEM analysis was performed to detect microbial colonization along crack surfaces. The results showed limited mechanical improvement, with slightly better performance in T1 and T2. However, no measurable crack width healing (CWH ≈ 0%) was detected, and no microbial growth was observed, likely due to high alkalinity, low surface porosity, and poor nutrient retention in the treated zone. Despite the modest outcomes, the study introduces an innovative approach that combines accelerated carbonation and surface biomineralization using a non-bacterial microorganism. For future studies, it is recommended to investigate multiple treatment applications, encapsulation systems for spore delivery, surface modification to enhance microbial adhesion, and local pH monitoring to ensure optimal conditions for microbial growth and activity.
2020-08-09
Baskaran, Sneha, Devarasan, Ezhilmaran
Baskaran, Sneha ; Devarasan, Ezhilmaran ; ABSTRACT Recycling solid waste is crucial for achieving sustainable development, as it enhances economic efficiency while preserving environmental stability. However, many solid waste image modalities are susceptible to noise and uncertainty, which can compromise the performance of automated waste classification systems. Neutrosophic sets (NS) provide a robust framework for managing such uncertainty by decomposing images into three components: truth (T), indeterminacy (I), and falsity (F). Unlike traditional representations, the NS framework explicitly models ambiguity and vagueness inherent in visual waste data. This study investigates the effectiveness of deep learning (DL) models integrated with the NS framework for solid waste classification using the TrashNet dataset. The original images are transformed into the neutrosophic domain, enabling their representation through these three distinct components. Four DL architectures—DenseNet121, DenseNet169, InceptionV3, and MobileNetV2 are trained on images processed within the neutrosophic environment. The performance of these models is evaluated and compared across both the NS and fuzzy set (FS) domains using key metrics such as accuracy, precision, recall, and F1-score. The experimental outcomes demonstrate that the NS framework outperforms the FS approach, with the neutrosophic falsity component achieving a maximum accuracy of 97.64% using InceptionV3, highlighting its potential for more reliable waste classification in real-world applications. Overall, the proposed neutrosophic–deep learning framework offers a robust and scalable solution for intelligent solid waste management, supporting sustainable smart-city initiatives.
2020-08-09
Silva, Fernanda Monique da, Paula, Edgley Alves de Oliveira, Rusch, Fernando, Pimenta, Alexandre Santos, Melo, Rafael Rodolfo de
Silva, Fernanda Monique Da ; Paula, Edgley Alves De Oliveira ; Rusch, Fernando ; Pimenta, Alexandre Santos ; Melo, Rafael Rodolfo De ; ABSTRACT The search for sustainability has led to the increased use of natural fibers, such as sisal. This study aimed to analyze the physical, mechanical, and thermal properties of sisal fibers from Brazil’s semi-arid region, enhancing their use as reinforcement in biocomposites. Tests were performed on density, diameter, moisture content, water absorption, tensile strength, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The fibers had an average density of 1.15 g/cm3, a maximum tensile strength of 242 MPa, a modulus of elasticity of 5,399 MPa, and a maximum deformation of 0.08 mm/mm. Thermogravimetric analysis (TGA/DTG) indicated good thermal stability of the fibers up to approximately 230ºC. The high-water absorption of the fibers highlighted the need for surface treatments to optimize fiber-matrix adhesion. The findings were essential for understanding the properties of sisal grown in northeastern Brazil, highlighting its potential as a reinforcement in biocomposites for developing new biodegradable, environmentally friendly, and high-performance products.
2020-08-09
Astudillo, Miriam Rocío Neyra, Spinosa, Cristina, Pumarega, Maria Isabel López, Gómez, Martín Pedro
Astudillo, Miriam Rocío Neyra ; Spinosa, Cristina ; Pumarega, Maria Isabel López ; Gómez, Martín Pedro ; ABSTRACT Austenite reversion, α'-martensite → γR-austenite reverted phase transformation, in AISI 304 steel was investigated. All the specimens had been subjected to a one-hour austenitizing heat treatment at 1050 °C in vacuum and with air cooling. Then, they were laminated at –70 °C, with a resulting total reduction of 63%. Finally, the samples thus generated were individually subjected to thermal annealing treatments for 1 hour, with increasing temperatures between 300 °C and 950 °C. In addition to microstructural changes and Vickers microhardness, the reversal process was studied through magnetic measurements: magnetic saturation and magnetic Barkhausen Noise (MBN). These measurements were carried out at room temperature. A temporal analysis of the MBN signals was done and their RMS (Root Mean Square) values were calculated. A similar trend was observed for the RMS of the MBN and the α' martensite contents, beyond the intrinsic differences in the techniques used to perform the measurements. Both techniques allow observing the evolution of the content of α' martensite or ferromagnetic phase as the temperature of the thermal reversion treatment increases.
2020-08-09
Dyson, Charles, Arputharaj, Anitha
Dyson, Charles ; Arputharaj, Anitha ; ABSTRACT This study explores the impact of elevated temperatures on the strengths of concrete samples, including standard mixes and various fiber-wrapped configurations (basalt, aramid, and combinations). Ambient temperature compressive strengths ranged from 21.01 MPa to 21.97 MPa, with minimal differences between standard and fiber-wrapped samples. Exposure to 250°C and 500°C caused significant reductions in compressive strength, with values dropping notably after 3 hours at 500°C. Split tensile strength at ambient temperature varied between 2.77 MPa and 4.04 MPa. Exposure to elevated temperatures resulted in substantial decreases, especially at 500°C after 3 hours, where strengths fell to 0.57–1.6 MPa. Tensile strength of prisms at ambient temperature ranged from 4.55 MPa to 5.37 MPa, decreasing notably after exposure to 500°C, with values dropping to 1.45–2.67 MPa after 3 hours. Fiber wrapping in cubes, cylinders, and prisms particularly with a combination of basalt and aramid strips helped in maintaining relatively higher tensile strengths, although strength reductions were still observed. The adopted mechanical properties were selected as governing parameters for evaluating the integrity of reinforced concrete members under thermal loading. The scope of this study is therefore to establish the potential of a hybrid basalt–aramid FRP wraps as a strengthening strategy for fire-prone concrete structures, providing a pathway towards field-scale applications and code-oriented design guidelines.
2020-08-09
Subramanian, Ramalingam
Subramanian, Ramalingam ; ABSTRACT Cerium oxide nanoparticles (CeNPs) are one of the most promising metal oxide nanoparticles, with a wide range of applications in the fields of environment, energy, industry, agriculture and biomedical sciences. Cerium oxide nanoparticles (CeNPs) also called as nanoceria was synthesized by precipitation method using two different precursors and characterized by X-ray diffraction (XRD) analysis, FTIR, SEM/EDX and DRS-UV-Visible spectroscopy for the structural, compositional, surface morphological and optical property studies. X-ray diffraction studies revealed that the crystallite structure of the ceria nanoparticles was cubic fluorite like with the crystallite size calculated (using the Debye-sherrer formula) was 5.1 nm for pure ceria nanoparticles and 2.8 nm for surfactant CTAB (cetyltrimethylammonium bromide) assisted CeNPs. As per the results of the EDX compositional analysis, the weight percent content of Ce and O in the formed cerium oxide nanoparticles was 78.7% and 21.3% (pure CeO2) and 79.3% and 20.7% (surfactant CTAB assisted nanoCeO2), respectively. SEM analysis confirmed the uniform distribution of CeNPs and the nanocube-like shape of CeNPs formed by the precipitation method. DRS-UV-Visible spectral studies shows that, pure ceria and surfactant assisted ceria exhibit UV-Visible absorption in the range of 320 nm to 346 nm and band gap energy values ranging from 2.4 to 2.6 eV. Surfactant assisted nanoceria shows absorption shifts to the visible region, and the band gap energy values decrease when compared to bulk ceria (Eg = 3.19 eV). The effect of surfactant CTAB on crystallite size and agglomeration, as well as increasing CeO2 product formation, has been observed.
2020-08-09
Li, Bo, Zhu, Zhaoyue, Kang, Aihong, Song, Guanchun, Kou, Changjiang, Wu, Xing
Li, Bo ; Zhu, Zhaoyue ; Kang, Aihong ; Song, Guanchun ; Kou, Changjiang ; Wu, Xing ; ABSTRACT Ecological river slope protection techniques have received considerable attention for sustainable development. This study focuses on a newly developed material called cast-in-situ vegetation concrete (CVC), which incorporates vegetation and punched holes. A series of anti-scouring tests were conducted to optimize its construction parameters. Wave scouring tests on bare slopes and rainfall scouring tests on vegetated slopes were carried out to evaluate the effects of flow velocity, rainfall intensity, slope gradient, punched hole parameters, and construction thickness on underlying soil erosion. Additionally, high-flow scouring tests were conducted to examine the overall survival status of vegetation after scouring under different construction thicknesses and perforation parameters. The results indicate that flow velocity, rainfall intensity, and slope gradient are positively correlated with soil erosion. Among these, Perforation Group A (4.5 cm in depth, 2.5 cm in diameter, 2.8 cm in spacing) demonstrated superior performance to Perforation Group B (4.0 cm in depth, 1.0 cm in diameter, 3.5 cm in spacing), exhibiting lower erosion volume and better vegetation-reinforced slope protection effects. In terms of promoting stable vegetation survival, construction thicknesses of 6 cm or 10 cm were found to be preferable to 15 cm. Therefore, the parameters of Perforation Group A with a thickness of 6 cm or 10 cm are recommended. These findings offer practical guidance for the application of Cast-in-place Vegetation Concrete (CVC) technology in ecological slope protection.
2020-08-09
Palanisamy, Vivekanandan, Ramanathan, Thirumalai, Chinnasamy, Natarajan, Andavar, Arun Thirumalaisamy
Palanisamy, Vivekanandan ; Ramanathan, Thirumalai ; Chinnasamy, Natarajan ; Andavar, Arun Thirumalaisamy ; ABSTRACT The cutting force, surface roughness, tool life, materials removal rate are generally evaluated by the efficiency of the cutting methods used in the industry. The machining process selected to machine a workpiece providing minimum surface roughness, maximum material removal rate, minimum cutting force, are considered to be highly efficient. However, in an industry, in specific the machining condition, the objective function gives contradictory requirements. In these cases, Multi Criteria Decision Making process is adopted to ensure equal importance for all the objective functions. In this paper, multi-criteria decision making study is presented for machining of steel using milling machine. The weights of the criteria are determined by four different methods, namely; equal weight, Rank Order Centroid (ROC) method, Rank Sum (RS) weighing method and Entropy weight. The Measurement Alternative and Ranking according to COmpromise Solution (MARCOS) method is applied for multi-criteria decision making. The best alternative is evaluated and the effects of ordering the criteria on decision making have been discovered.