Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttps://hdl.handle.net/10321/215

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Modelling radium equivalent activity from 226Ra, 232Th, and 40K series of recycled waste materials : analytical and artificial intelligence approaches
(Springer Science and Business Media LLC, 2025-1) Oyebisi, Solomon; Shammas, Mahaad Issa; Jagadesh, P; Owamah, Hilary; Oyewola, Miracle Olanrewaju
Primordial radionuclides in the decay sequence beginning with 238U, 232Th, and 40K, as well as cosmic radiation, account for most of the natural radiation in environments and humans. Construction and building materials contain primordial radionuclides. This research predicts the radium equivalent activity (Raeq) from the 226Ra, 232Th, and 40K concentrations of recycled waste materials using the deep neural networks of artificial intelligence. The Levenberg-Marquardt backpropagation technique was used to train the network, which had a three-hidden layer structure and 5–30 neurons in each layer. Predicting the Raeq of recycled waste materials was achieved with high precision using all network architectures. The best performance metrics for training, validation, and testing were demonstrated by a 3-15-15-15-1 network architecture. Furthermore, using untrained data, a robust correlation of 0.9996 R2 was obtained from the model’s confirmation.
Analysis and measurement of Tuberculin skin test induration using deep neural network
(International Association of Online Engineering (IAOE), 2024-9-13) Akinola, Olubunmi Adewale; Orimolade, Joseph Folorunsho; Afolabi, Akindele Segun; Shopeju, Habeeb Kehinde; Adetiba, Emmanuel; Adewale, Adeyinka Ajao
The World Health Organization (WHO) posited that tuberculosis (TB) is among the world’s ten greatest causes of mortality. Early case identification and timely treatment could minimize TB morbidity and death rates. This study adopts the UNets model for automatically detecting TB in subjects by using a deep neural network to assess the size of induration after tuberculin was injected into their hands. In order to do this, two neural network models were fine-tuned utilizing pre-learned weights from the 2012 ILSVRC ImageNet. Algorithms were developed to perform semantic segmentation of induration and compare it to that of a reference object of a known dimension. This was used to classify the status of the subject as either positive or negative. A series of experiments performed demonstrated that the optimal selection of neural network hyperparameters may provide a satisfactorily high F1 score of up to 0.977.
Unraveling the root causes of low overall equipment effectiveness in the kit packing department: a Define–Measure–Analyze–Improve–Control approach
(MDPI AG) Mncwango, Bongumenzi; Mdunge, Zithobe Lisanda
Low Overall Equipment Effectiveness (OEE) remains a critical challenge in manufacturing, affecting productivity and operational efficiency. This study investigates the persistent issue of low OEE in the kit packing department of a South African Original Equipment Manufacturer, where frequent downtime (DT) has resulted in OEE that is consistently below 60%. Using the Define–Measure–Analyze–Improve–Control (DMAIC) methodology, this research identifies the root causes of inefficiencies before implementing corrective actions. Data analysis revealed that material-related issues (84%) and manpower issues (15%) were the primary contributors to downtime. These inefficiencies led to equipment underutilization and financial losses due to production delays and overproduction of unnecessary kits. This study significantly enhances manufacturing efficiency by addressing these root causes, leading to reduced downtime and optimized machine usage. The financial benefits include substantial cost savings and improved resource utilization. The methodology and findings are applicable across various industries, contributing to the broader field of industrial engineering. The research highlights how misalignment between production planning and execution exacerbates inefficiencies. While this paper presents findings from the Define, Measure, and Analyze phases, the Improve and Control phases will follow in future work. The results provide a foundation for developing targeted interventions to enhance OEE and manufacturing performance.
A new Fermatean fuzzy Spearman-like correlation coefficient and its application in evaluating insecurity problem via multi-criteria decision-making approach
(Elsevier BV, 2024-11) Ejegwa, Paul Augustine; Kausar, Nasreen; Aydin, Nezir; Feng, Yuming; Olanrewaju, Oludolapo Akanni
The problem of insecurity is a global crisis with adverse effects on lives and properties. Fermatean fuzzy correlation coefficient is a dependable method for handling imprecision, which is the main bottleneck of insecurity assessment. A number of Fermatean fuzzy correlation coefficient methods have been developed. Based on Spearman's correlation coefficient, an innovative Fermatean fuzzy correlation coefficient method is built to enhance trustworthy insecurity assessment. The existing Fermatean fuzzy correlation coefficient methods are evaluated, and their shortcomings are identified in order to validate the construction of a new Fermatean fuzzy correlation coefficient method. The drawbacks of the existing methods lead us into building a new Fermatean fuzzy correlation coefficient method by using the Spearman's correlation coefficient approach, which has the potential of overcoming the drawbacks of the existing Fermatean fuzzy correlation coefficient methods. In addition, some theoretical findings are provided to support the strength of the novel Fermatean fuzzy correlation coefficient method and it is shown that the new method satisfies the Fermatean fuzzy correlation coefficient requirements. Furthermore, the novel Fermatean fuzzy correlation coefficient method is applied to assess the insecurity situation in the North-Central Region of Nigeria to furnish intended tourists with relevant travel advice. To demonstrate the inherent significance of the novel Fermatean fuzzy correlation coefficient method, we compare its effectiveness to that of the extant Fermatean fuzzy correlation coefficient methods. The results of the comparison show the superiority of the novel Fermatean fuzzy correlation coefficient method over the existing ones in terms of reliability, consistency, precision and compliance with the Fermatean fuzzy correlation coefficient axioms. Ultimately, it is discovered that the new method can effectively address hesitations related to insecurity assessment.
Investigating top-down cracking of pavement in recycled waste plastic asphalt
(Materials Research Forum LLC, 2025-3-25) Abejide, Samuel; Adedeji, Jacob; Mostafa, Mohamed Mostafa Hassan
Abstract. This study investigates a new approach for the use of an alternative sustainable wearing course material on flexible pavement roads (recycled asphalt plastic pavement). Highway infrastructure plays a major key role in the domestic transportation of people, goods and services within the community and from a national perspective. Thus, highway infrastructure provides provincial and local accessibility, which promotes the growth and development of the economy. For this reason, there is a need to develop a sustainable approach to increase the efficiency of transportation infrastructure. The purpose of this study was to evaluate top-down fatigue cracking failure mode of asphaltic wearing courses for use in in pavement overlays, at high traffic intersection points and on parking sections using dual tire loads in finite element analysis. The process of developing alternative mixing materials is initiated by the need to provide a stable mixture for use on field sections different from cold mix or conventional hot mix (HMA) materials, which is subjected to stripping delamination mode with increasing moisture content. In this study, it was observed that the bonds formed between the molten plastic material has the potential to bind the bitumen and the aggregates together as a homogenous material in such a way that, when hardened at reduced temperatures, the mix is able to form a stronger bonded material that is semipervious and allows drainage of moisture or water across the surface of the asphalt plastic layer. This study adopts an alternative approach to the design of an ultrathin film asphalt concrete porous pavement layer for use in pavement surface wearing course and high-density traffic roads considering the effects of increasing temperature and moisture absorption on the asphalt plastic pavement mix.
Exploration of free and immobilized biocatalysts for the treatment of paper industry effluents
(Informa UK Limited, 2025-7-3) Tite, Toritsegbone Erik; Ngema, Peterson Thokozani; Makhathini, Thobeka Pearl
The complex mixture of pollutants found in industrial effluents creates a significant environmental challenge. Enzymatic treatment offers a promising alternative to traditional physiochemical techniques. With an emphasis on laccase enzymes, this review examines the potential of both free and immobilized biocatalysts for the treatment of industrial wastewater, especially from pulp and paper mills. Laccase has become one of the most popular options for bioremediation because of its broad substrate specificity and capacity to break down different kinds of organic pollutants. The different methods of laccase immobilization, including adsorption, encapsulation and cross-linking are examined, exploring their advantages and limitations. The benefits of immobilization for enzyme stability, reusability and operational efficiency in wastewater treatment processes are further discussed. By comparing the advantages and limitations of free and immobilized biocatalysts, this review aims to provide valuable insights for the development of efficient and sustainable enzymatic strategies for industrial wastewater treatment. Furthermore, this paper offers future possibilities for using biocatalyst in pulp and paper waste treatment.
Speech to speech translation with translatotron : a state of the art review
(2025-2-9) Kala, Jules R.; Adetiba, Emmanuel; Abayom, Abdultaofeek; Dare, Oluwatobi E.; Ifijeh, Ayodele H.
A cascade-based speech-to-speech translation has been considered a benchmark for a very long time, but it is plagued by many issues, like the time taken to translate a speech from one language to another and compound errors. These issues are because a cascade-based method uses a combination of methods such as speech recognition, speech-to-text translation, and finally, text-to-speech trans lation. Translatotron, a sequence-to-sequence direct speech-to-speech translation model was designed by Google to address the issues of compound errors associated with cascade model. Today there are 3 versions of the Translatotron model: Trans latotron 1, Translatotron 2, and Translatotron3. The first version was designed as a proof of concept to show that a direct speech-to-speech translation was possible, it was found to be less effective than the cascade model but was producing promising results. Translatotron2 was an improved version of Translatotron 1 with results sim ilar to the cascade model. Translatotron 3 the latest version of the model is better than the cascade model at some points. In this paper, a complete review of speech to-speech translation will be presented, with a particular focus on all the versions of Translatotron models. We will also show that Translatotron is the best model to bridge the language gap between African Languages and other well-formalized languages.
Sound absorption capacity of hot and warm asphaltic mixes modified with waste plastic bottles
(IOP Publishing, 2025-4-1) Akinleye, Monsuru; Oyebisi, Solomon; Reuben, Sani
Vehicular traffic is one of the noise-producing factors contributing to environmental problems. Utilizing special asphaltic mixes can help reduce noise generation. Thus, this research evaluated the sound absorption capacity (SAC) of hot mixed asphalt (HMA) and warm mixed asphalt (WMA) modified with pyrolyzed polyethylene terephthalate (PET) bottles varying at 1-17 wt. %. PET bottles were pyrolyzed at 450 °C for a 2 h retention period, obtaining pyrolyzed PET bottle (PTB). HMA and WMA were prepared with 0-17 wt. % PTB and the SAC values were tested. The results were compared to a control mix, a standard HMA or WMA without any PTB modification, to provide a baseline for the evaluation. The effects of volumetric and Marshall properties of HMA and WMA on SAC were correlated. The results revealed decreased sound levels with increasing PTB dosage in the HMA. However, WMA generated increased sound levels as PTB content increased from 1-9 wt. % but decreased after 9 wt. % of PTB substitution. HMA and WMA performed best at 11 and 7 wt. % PTB with corresponding SAC values of 78.23 and 80.53 dB compared to the control mix with 79.33 dB.
CO2 methanation: a bibliometric analysis and review of activated carbon-based materials (2014–24)
(Oxford University Press (OUP), 2024-12-1) Akpasi, Stephen Okiemute; Isa, Yusuf Makarfi; Monama, Thembisile Patience; Kiambi, Sammy Lewis; Ngema, Peterson Thokozani
This study highlights the significant potential of activated carbon (AC)-based materials in environmental remediation and energy production, particularly in converting carbon dioxide (CO2) and hydrogen (H2) into methane (CH4) and water (H2O) using transition metal-based catalysts. It emphasizes the role of porous AC in waste reduction and resource utilization, examining various applications of CO2 and evaluating environmental impacts. The research explores commercialization opportunities and specifically investigates CO2 methanation using AC-based materials. Using bibliometric analyses of 4196 articles from the Web of Science database, the study identifies a growing research interest in porous AC-related CO2 methanation from 2014 to 2024. The top three journals in this field are Environment Development and Sustainability, Biomass Conversion and Biorefinery, and Journal of Environment Science and Pollution. However, there is limited inter-institutional collaboration in this field, suggesting room for development towards commercializing sustainable CH4 production pathways. CH4 is highlighted as a crucial intermediate in industrial processes, and research directions are identified through co-occurring author keywords analysis. The study suggests the need for a comprehensive approach integrating AC materials into carbon-neutral energy processes while addressing the potential adverse effects of AC nanoparticles on biological and environmental factors. Ultimately, it clarifies the potential uses and commercialization prospects for porous AC materials, especially in conjunction with carbon capture and utilization technologies, promoting sustainable practices in energy production and environmental management.
Anticorrosion behaviour of Rhizophora mangle L. Bark-extract on concrete steel-rebar in saline/marine simulating-environment
(Hindawi Limited, 2019-1) Okeniyi, Joshua Olusegun; Ikotun, Jacob Olumuyiwa; Akinlabi, Esther Titilayo; Okeniyi, Elizabeth Toyin
This paper investigates anticorrosion behaviour of the bark-extract from Rhizophora mangle L on steel-rebar in concrete slabs in 3.5% NaCl medium of immersion (for simulating saline/marine environment). Corrosion-rate, corrosion-current, and corrosion-potential were measured from the NaCl-immersed steel-reinforced concrete cast with admixture of different plant-extract concentrations and from positive control concrete immersed in distilled water. Analyses indicate excellent mathematical-correlation between the corrosion-rate, concentration of the bark-extract admixture, and electrochemical noise-resistance (ratio of the corrosion-potential standard deviation to that of corrosion-current). The 0.4667% Rhizophora mangle L. bark-extract admixture exhibited optimal corrosion-inhibition performance, η = 99.08±0.11% (experimental) or η = 97.89±0.24% (correlation), which outperformed the positive control specimens, experimentally. Both experimental and correlated results followed Langmuir adsorption isotherm which suggests prevalent physisorption mechanism by the plant-extract on the reinforcing-steel corrosion-protection. These findings support Rhizophora mangle L. bark-extract suitability for corrosion-protection of steel-rebar in concrete structure designed for immersion in the saline/marine environmental medium.
Design and construction of a smart meter with embedded web portal
(Science Publications, 2024-8-1) Mike-Ewewie, David; Ifijeh, Ayodele; Oguntosin, Victoria; Adetiba, Emmanuel
The absence of the necessary infrastructure to make an accurate and precise collection of data when compared to the firstworld countries in the power industry is great. Due to that, the need for the deployment of smart meters has increased in order to offer consumers and customers awareness of their electricity usage, helping them lower their total energy footprint. In this study, realtime low-cost energy management is designed and developed with an embedded web server integration. Using both real and reactive power data obtained from the smart energy system, the power quality can be made better for people taking their power straight from the grid. The work drives building a smart metering solution that helps in the process of monitoring. This smart metering solution involves connecting a load displacement sensor, which is an example of a smart sensor, to a web server, which tracks power consumption. It is mainly utilized for managing the overall power plant and measuring the major power system quantities. Data compression is employed for measurements of power quality and for speeding up the process of data loss prevention. When excess electricity usage occurs, the electrical energy is disconnected from the grid. Future residences will be designed to provide a high degree of interconnectivity and scalability. We demonstrate that by utilizing the foundational ideas of modern Web architecture, we can quickly and simply construct reliable, versatile smart Meter applications with few drawbacks.
Bioremediation: Data on biologically-mediated remediation of crude oil (Escravos Light) polluted soil using Aspergillus niger
(Elsevier BV, 2018-8) Ojewumi, Modupe Elizabeth; Okeniyi, Joshua Olusegun; Okeniyi, Elizabeth Toyin; Ikotun, Jacob Olumuyiwa; Ejemen, Valentina Anenih; Akinlabi, Esther Titilayo
This article presents data on Aspergillus niger effects on the biologically-mediated remediation of soil polluted by raw and treated crude oil (Escravos Light blend). Absorbance of different concentrations of polluted soil samples (5% and 8% w/w) and types (raw and treated), for simulating different onshore crude oil spill, were obtained from the A. niger inoculated samples using ultra violet–visible (UV–Vis) spectrophotometry. This measurement was carried out for each sample at selected intervals for the 30-day measurements. The bioremediation data, presented in the article, were subjected to descriptive/analytical statistics of probability density functions and goodness-of-fit test-statistics for datasetdetailing and dataset-comparisons. Information details from these data of biologicallymediated remediation of crude oil polluted soil are useful for furthering research on bioremediation kinetics such as hydrocarbon content analyses, crude oil pollutant removal performance, biodegradation rate parameter and biostimulant efficiencies by the A. niger effects on the different concentrations of polluted soil.
Quantum PSO-based power demand and supply management algorithm for Micogrids
(Collegium Basilea, 2024-11-22) Mgobhozi, Bhekinkosi; Nleya, Bakhe
In this paper, we formulate a day-ahead dispatch problem of microgrids with distributed generation (DG) subject to the non-convex cost function. An operational frame- work is proposed to address the DGs 'valve-point' loading effect and optimize its performance. The valve-point effect induces a ripple in a 'fuel-cost' curve. The impact of demand side management (DSM) on convex and non-convex energy management system (EMS) problems with different load participation levels is investigated. Further, the DA scheduling horizon of a fifteen-minute resolution time is considered to examine the effect of load dynamics in the MG. The new optimization algorithm, Quantum Particle Swarm Optimization (QPSO), is employed to solve the non-convex DGs cost optimization problem. It is demonstrated that the algorithm efficiently solves the EMS problem. Simulation results point to a 5% reduction in OPEX costs with a minimal penalty on customer satisfaction or Utility.
3D mmWave MIMO channel modeling and reconstruction for street canyon and highrise scenarios
(IEEE, 2024-4-2) Idowu-Bismark, Olabode; Oshin, Oluwadamilola; Adetiba, Emmanuel; Idowu-Bismark, Oluwatobiloba
The use of millimeter-wave (mmWave) and full-dimensional multiple-input multiple-output (FD-MIMO) antenna systems for 3D wireless communication is being exploited for enhanced network capacity improvement in the ongoing fifth-generation (5G) deployment. For adequate assessment of competing air interface, random access channelization, and beam alignment procedures in mmWave systems, channel models for different use scenarios are necessary. A ray-tracing study was conducted with the use of a Wireless Insite ray tracing algorithm to characterize the mmWave channel in urban areas, using Lagos Island, Nigeria databases to predict measured statistics. These statistics include path loss, rms delay spread, angular spread of arrival, and departure in the azimuth and elevation domain. A 3GPP-style 3D mmWave channel is modeled and reconstructed, emphasizing the use of a ray tracer to determine elevation model parameters. Line of sight (LOS) and non-line of sight (NLOS) 3D models were developed for street canyon and high-rise scenarios
Revolutionizing eco-friendly concrete : unleashing pulverized oyster shell and corncob ash as cement alternatives for sustainable building
(Elsevier BV, 2025-7) Oyebisi, Solomon; Alomayri, Thamer
The utilization of Portland cement (PC) as a conventional binder in concrete production is not completely eco friendly, spurring research into finding a more ecologically friendly way to produce concrete. This study recycles waste materials such as corncob ash (CCA) and pulverized oyster shell (POS) as alternative binders at 5–15 wt% of PC for ternary blended concrete (TBC) production and tested for mechanical properties after 3–120 curing ages and durability performance after 120 days of immersion in 5 % of acidic and sulfate solutions. The embodied energy (EE) and global warming potential (GWP) of TBC compositions were analyzed within cradle-to-gate constraints, and the sustainability and economic indexes were evaluated. Microstructural characterization was performed on concrete samples after 28 curing ages. The results indicated that CCA and POS incorporation reduced TBC’s slump and early age strengths. However, the later age strengths were superior at 10 wt% CCA and POS replacement level with 1–8 %, 1–7 %, and 1–9 % increases in compressive, flexural, and split tensile strengths after 28–120 curing ages compared to the control samples. Adding 10 wt% CCA and POS contents to TBC enhances its resistance to chemical attacks, reduces its EE and GWP by 19–25 % and 19–20 %, and increases its sustainability score and eco-strength efficiency by 25 and 17 % compared to the control concrete. Incorpo rating CCA and POS into the TBC mix contributes C-A-S-H for strength development. Ultimately, this study offers ecofriendly and durable concrete at 10 wt% CCA and POS substitution for sustainable building.
Risk exposure in recycled agro-industrial waste : radioactive sources and potential effects
(Springer Science and Business Media LLC, 2025-4-1) Oyebisi, Solomon
Surveyed agricultural byproducts pose no radioactive risk. Most industrial byproducts studied pose radioactive risks. Agricultural and industrial byproducts are significantly influenced by 40K and 232Th.
Exploring the suitability of Bambusa Vulgaris Leaf Ash as a biomass filler in asphalt mixtures
(Springer Science and Business Media LLC, 2025-1-1) Akinleye, Monsuru; Oyebisi, Solomon; Sathvik, S.; Salami, Lukman; Joseph, Oluwatoyin; Alomaja, Jonathan
Utilizing waste as alternative materials in asphalt production preserves natural resources and reduces environmental impacts. This study investigates the potential of Bambusa Vulgaris Leaf Ash (BVLA) as a potential biomass filler in place of conventional mineral filler, Powdered Quarry Dust (PQD), in producing asphalt mixtures. Dried Bambusa Vulgaris leaves were obtained locally and calcined at 600 °C for 2 h, generating BVLA. PQD was replaced with BVLA at 0–100 wt. %. The effects of BVLA filler on the mechanical properties of asphalt mixtures were evaluated using Marshall Quotient (MQ) and indirect tensile strengths. Similarly, the durability of asphalt mixtures was assessed through moisture susceptibility (tensile strength ratio). The environmental impacts (embodied energy and global warming potential), sustainability score, and eco-strength efficiency of incorporating BVLA as a PQD alternative were evaluated using the cradle-to-gate boundary. The results revealed improved mechanical and durability properties with increased BVLA dosage in the asphalt mixtures. However, the optimum replacement level was found at 30 wt. % BVLA, resulting in 37.43, 22.22 and 22.39, and 4% higher MQ, wet and dry indirect tensile strengths, and tensile strength ratio compared to the control mixture (PQD-based asphalt mixture). With a 30 wt. % optimum BLVA dosage in the asphalt mixtures, the embodied energy and global warming potential decreased by 5 and 50%, while the sustainability score and eco-strength efficiency increased by 50 and 34%. These findings underscore the potential of BVLA to enhance pavement construction properties and promote sustainability.
A review on barrier properties of cellulose/clay nanocomposite polymers for packaging applications
(MDPI AG, 2023-12) Jali, Sandile; Mohan, Turup Pandurangan; Mwangi, Festus Maina; Kanny, Krishnan
Packaging materials are used to protect consumer goods, such as food, drinks, cosmetics, healthcare items, and more, from harmful gases and physical and chemical damage during storage, distribution, and handling. Synthetic plastics are commonly used because they exhibit sufficient characteristics for packaging requirements, but their end lives result in environmental pollution, the depletion of landfill space, rising sea pollution, and more. These exist because of their poor biodegradability, limited recyclability, etc. There has been an increasing demand for replacing these polymers with bio-based biodegradable materials for a sustainable environment. Cellulosic nanomaterials have been proposed as a potential substitute in the preparation of packaging films. Nevertheless, their application is limited due to their poor properties, such as their barrier, thermal, and mechanical properties, to name a few. The barrier properties of materials play a pivotal role in extending and determining the shelf lives of packaged foods. Nanofillers have been used to enhance the barrier properties. This article reviews the literature on the barrier properties of cellulose/clay nanocomposite polymers. Cellulose extraction stages such as pretreatment, bleaching, and nanoparticle isolation are outlined, followed by cellulose modification methods. Finally, a brief discussion on nanofillers is provided, followed by an extensive literature review on the barrier properties of cellulose/clay nanocomposite polymers. Although similar reviews have been presented, the use of modification processes applied to cellulose, clay, and final nanocomposites to enhance the barrier properties has not been reviewed. Therefore, this article focuses on this scope.
Analysis of particle variation effect on flexural properties of hollow glass microsphere filled epoxy matrix syntactic foam composites
(MDPI AG, 2022-11) Afolabi, Olusegun Adigun; Kanny, Krishnan; Mohan, Turup Pandurangan
Syntactic foam made from hollow glass microspheres (HGM) in an epoxy matrix has proven to be a good material with a strong structural strength. Understanding filler particle size variation is important in composite material formation, especially in syntactic foam, because of its numerous applications such as aerospace, marine, and structural purposes. In this present work, the effects of particle variation in different sizes (20-24 µm, 25-44 µm, 45-49 µm, and 50-60 µm) on the mechanical properties of the syntactic foam composites with a focus on flexural strength, modulus, and fracture surfaces are investigated. The particle sizes are varied into five volume fractions (5, 10, 15, 20, and 25 vol%). The results show that the highest flexural strength is 89 MPa at a 5 vol% fraction of 50-60 µm particle size variation with a 69% increase over the neat epoxy. This implies that the incorporation of HGM filler volume fraction and size variation has a strong effect on the flexural strength and bending modulus of syntactic foam. The highest particle size distribution is 31.02 at 25-44 µm. The storage modulus E' increased at 30 °C, 50 °C, and 60 °C by 3.2%, 47%, and 96%, respectively. The effects of wall thickness and aspect ratio on the size of the microstructure, the fracture surfaces, and the viscoelastic properties are determined and reported accordingly.
Processing of low-density HGM-filled epoxy-syntactic foam composites with high specific properties for marine applications
(MDPI AG, 2023-2) Afolabi, Olusegun Adigun; Mohan, Turup Pandurangan; Kanny, Krishnan
A solution casting approach is used to create hollow glass microsphere (HGM)-filled epoxy-syntactic foam composites (e-SFCs) by varying the concentrations of HGM in epoxy according to different particle sizes. Density analysis is used to investigate the impact of concentration and particle size regularity on the microstructure of e-SFCs. It was observed that e-SFCs filled with an HGM of uniform particle sizes exhibit a reduction in density with increasing HGM concentration, whereas e-SFCs filled with heterogeneous sizes of HGM exhibit closeness in density values regardless of HGM concentration. The variation in e-SFC density can be related to HGM packing efficiency within e-SFCs in terms of concentration and particle size regularity. The particle size with lowest true density of 0.5529 g/cm3, experimental density of 0.949 g/cm3 and tensile strength of 55.74 MPa resulted in e-SFCs with highest specific properties of 100.81 (MPa·g/cm3), with a 35.1% increase from the lowest value of 74.64 (MPa·g/cm3) at a true density of 0.7286 g/cm3, experimental density of 0.928 g/cm3 and tensile strength of 54.38 MPa. The e-SFCs' theoretical density values were obtained. The variance in theoretical and experimental density values provides a thorough grasp of packing efficiency and inter-particle features.

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