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AbstractRecycled tire steel fiber reinforced geopolymer concrete provides a sustainable and circular economy-based alternative to traditional steel fiber reinforced concrete, wherein steel wires derived from recycling of end-of-life tires are used as alternative fiber reinforcement, while cement is completely replaced with industrial wastes like fly ash and slag. This study presents the current state-of-knowledge on the engineering properties of recycled steel wires reinforced geopolymers wherein mechanical properties, rheology, durability, and microstructural investigations of recycled steel wires reinforced geopolymer composites were discussed and compared with industrial steel fibers reinforced geopolymers. A life cycle assessment was also performed to compare the environmental impacts of recycled steel wires reinforced geopolymers with steel and polypropylene fiber-reinforced geopolymers. The inclusion of recycled steel wires positively impacted the mechanical properties of geopolymer concrete, whereas rheology was adversely affected. Microstructural investigations indicated a compact geopolymer with strong fiber-matrix bond resulting from the presence of residual rubber on the fiber surface. There were a lot of discrepancies and limitations pertaining to durability in the literature. Life cycle assessment indicated a 40% reduction in greenhouse gas emissions of steel fiber and polypropylene fiber reinforced geopolymer by replacing them with recycled steel wires, indicating the sustainability and circular economy potential of recycled steel wires. [ABSTRACT FROM AUTHOR]

This study investigates the production of waste tire pyrolyzed oil on a laboratory scale and its potential use as a fuel along with biogas and hydrogen in a variable-speed transportation engine. The pyrolyzed oil, obtained from waste tire pieces through a lab-scale plant, undergoes distillation and is blended with diesel fuel in a 20% ratio. This blended fuel is supplied to a multi-cylinder variable-speed transportation engine, either alongside biogas or HHO separately or both combined, at fixed flow rates with air passage through a premixing device (venturi). This study aimed to assess engine combustion characteristics such as in-cylinder pressure and heat release rate; performance parameters, including brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC), as well as emissions of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). The results indicate that using pyrolyzed oil in unmodified diesel engines reduces combustion characteristics and performancewhile increasing HC and NOx emissions and decreasing CO emissions. In addition, supplying biogas and the fuel mixture further deteriorates combustion and performance, while increases HC and CO emissions, and reduces NOx emissions. The focus of the present research is to evaluate the impact of adding green hydrogen (HHO) gas to a pyrolyzed oil fuel mixture and a biogas-led fuel mixture in a compression ignition (CI) engine. The results indicate that the addition of hydrogen enhances combustion characteristics, engine performance and reduces emissions, except for NOx. Specifically, there is an increase in cylinder peak pressure and HRR by around 6–10% range, improvement in BTE by 16–20% and BSFC by 5–7%, along with a decrease in HC and CO emissions by 13–16% and 11–13%, respectively. However, there is an increase in NOx emissions of 6–9%. In essence, the addition of green hydrogen enhances engine performance and reduces emissions in waste tire-derived pyrolyzed oil and biogas blends, indicating a viable path for sustainable transportation fuel. • Pyrolyzed tire oil blended with diesel fuel (20%) tested in variable-speed engines. • Adding biogas to the fuel blend worsens performance and increases HC and CO emissions. • Green hydrogen (HHO) improves combustion and performance in the fuel blend. • HHO addition increases cylinder peak pressure and heat release rate by 6–10%. • HHO addition enhances BTE by 16–20% and reduces HC and CO emissions by 13–16% and 11–13%, respectively. [ABSTRACT FROM AUTHOR]

In this present investigation, epoxy nanocomposites were formulated with multiwalled carbon nanotubes derived from plastic (p‐MWCNTs), carbon black from tires (t‐CB), and a combination of p‐MWCNTs and functionalized carbon black (FCB). A comparative analysis was conducted between the properties of the original composites and epoxy nanocomposites containing a mixture of carbon nanotube (CNT) and FCB. Morphology, carbon content, and oxide content of CB and FCB were assessed using field emission scanning electron microscopy (FESEM) and energy‐dispersive x‐ray spectroscopy (EDS or EDX). The dispersion of CNT and the CNT/FCB blend in water was observed using ultraviolet–visible spectroscopy (UV–VIS). Furthermore, Fourier transform infrared spectroscopy and x‐ray diffraction analyses were performed on CNT, CB, and FCB to comprehend the presence of functional groups and structural changes with chemical treatment. The nanocomposites were created by employing diglycidyl ether of bisphenol A (DGBEA) epoxy resin through a simple sonication and casting method. The tensile strength of CNT/FCB epoxy composites showed a significant increase, rising from 66.26 MPa to 158.48 MPa, marking a 139.17% improvement over pure epoxy. This improvement is likely due to the bonding interaction between the epoxy, FCB, and CNTs which resulted a uniform dispersion of fillers onto epoxy matrix. Conversely, the impact strength initially increased from 112.84 J/m (pure epoxy) to 144.05 J/m (FCB), but then decreased to 115.7 J/m for CNT/FCB composites. FCB demonstrated a 27.65% increase in impact strength compared to pure epoxy. Moreover, the thermal stability of the samples exhibited improvement from neat epoxy to CNT/FCB‐based nanocomposites. Highlights: Oxygen content of CB increased from 25.17% to 54.60%.CNT/FCB epoxy composites exhibited a 139.17% increase in tensile strength.FCB epoxy composites shows 27.65% increase in impact strength.Thermal stability of CNT/FCB composites increased by 1.89%.Crosslinking via covalent bonding occurred between FCB and epoxy. [ABSTRACT FROM AUTHOR]

The goals of this study are to assess the viability of waste tire-derived char (WTDC) as a sustainable, low-cost fine aggregate surrogate material for asphalt mixtures and to develop the statistically coupled neural network (SCNN) model for predicting volumetric and Marshall properties of asphalt mixtures modified with WTDC. The study is based on experimental data acquired from laboratory volumetric and Marshall properties testing on WTDCmodified asphalt mixtures (WTDC-MAM). The input variables comprised waste tire char content and asphalt binder content. The output variables comprised mixture unit weight, total voids, voids filled with asphalt, Marshall stability, and flow. Statistical coupled neural networks were utilized to predict the volumetric and Marshall properties of asphalt mixtures. For predictive modeling, the SCNN model is employed, incorporating a three-layer neural network and preprocessing techniques to enhance accuracy and reliability. The optimal network architecture, using the collected dataset, was a 2:6:5 structure, and the neural network was trained with 60% of the data, whereas the other 20% was used for cross-validation and testing respectively. The network employed a hyperbolic tangent (tanh) activation function and a feed-forward backpropagation. According to the results, the network model could accurately predict the volumetric and Marshall properties. The predicted accuracy of SCNN was found to be as high value >98% and low prediction errors for both volumetric and Marshall properties. This study demonstrates WTDC's potential as a low-cost, sustainable aggregate replacement. The SCNN-based predictive model proves its efficiency and versatility and promotes sustainable practices. [ABSTRACT FROM AUTHOR]

The global annual production of plastics and tires exceeds 6.5 billion tons, with only 10% being recycled, leading to significant environmental problems. Thermochemical gasification of these waste materials offers a potential avenue for producing renewable hydrogen while harnessing underutilized carbon-based waste streams. This review highlights the research on thermochemical conversion of plastics and tires, providing key inferences regarding yield optimization, technical hurdles, and techno-economic viability. It indicates that strategic catalyst design and optimized integrated system configurations can significantly improve the hydrogen yields from plastic and tire pyrolysis/gasification. The key results of this work are that catalyzed gasification reactions show the most potential for maximizing hydrogen yield from plastic and tire waste. The related studies demonstrated that catalysts like Ni, Fe and Ce-doped mixtures can significantly increase hydrogen yield from plastic waste pyrolysis and gasification by suppressing coke formation and promoting reforming/shift reactions. Optimization of temperature, steam ratio and residence time also improves yield. Feedstock synergies exhibiting multiple reaction pathways likewise maximize yield. Computational modeling plays a valuable role by providing mechanistic insights through equilibrium and kinetic simulations. Integrated gasification with carbon/methane reforming shows potential to improve efficiency and lower costs. Techno-economic analyses indicate plastic/tire gasification may achieve cost parity with steam methane reforming through optimized integrated designs incorporating heat recovery. Integrated processes combining multiple conversion steps could further boost efficiency but require additional modeling and testing. A deeper understanding of reaction mechanisms, achieved through advanced modeling approaches, coupled with comprehensive lifecycle analyses of integrated solutions, can pinpoint optimized processing conditions and system designs capable of matching or surpassing the economic and environmental performance of conventional fossil fuel-based hydrogen production. The recommendations provided aim to guide future research prioritization, facilitating the realization of the large-scale potential inherent in waste-derived renewable hydrogen pathways. [Display omitted] [ABSTRACT FROM AUTHOR]

The goals of this study are to assess the viability of waste tire-derived char (WTDC) as a sustainable, low-cost fine aggregate surrogate material for asphalt mixtures and to develop the statistically coupled neural network (SCNN) model for predicting volumetric and Marshall properties of asphalt mixtures modified with WTDC. The study is based on experimental data acquired from laboratory volumetric and Marshall properties testing on WTDC-modified asphalt mixtures (WTDC-MAM). The input variables comprised waste tire char content and asphalt binder content. The output variables comprised mixture unit weight, total voids, voids filled with asphalt, Marshall stability, and flow. Statistical coupled neural networks were utilized to predict the volumetric and Marshall properties of asphalt mixtures. For predictive modeling, the SCNN model is employed, incorporating a three-layer neural network and preprocessing techniques to enhance accuracy and reliability. The optimal network architecture, using the collected dataset, was a 2:6:5 structure, and the neural network was trained with 60% of the data, whereas the other 20% was used for cross-validation and testing respectively. The network employed a hyperbolic tangent (tanh) activation function and a feed-forward backpropagation. According to the results, the network model could accurately predict the volumetric and Marshall properties. The predicted accuracy of SCNN was found to be as high value ​>98% and low prediction errors for both volumetric and Marshall properties. This study demonstrates WTDC's potential as a low-cost, sustainable aggregate replacement. The SCNN-based predictive model proves its efficiency and versatility and promotes sustainable practices.

Abstract The addition of polymer fibers to cemented paste backfill (CPB) has shown promise in enhancing mechanical properties, although it also introduces changes in rheological characteristics. This study aimed to investigate the influence of different types of polymer fibers, namely virgin commercial polypropylene fiber (CPPF), recycled tire polymer fiber (RTPF), and recycled tire rubber fiber (RF), on the rheological properties of CPB mixtures through an experimental program, and provide design references for CPB pipeline transport. The results revealed consistent reductions in bulk density upon the incorporation of polymer fibers into CPB, alongside varying impacts on slump. Specifically, the addition of CPPF had a mild effect, while RTPF caused a continuous decrease in slump, and RF exhibited minimal influence up to a 4% concentration, with substantial effects thereafter. Moreover, the inclusion of fibers led to increases in apparent viscosity parameters, with RTPF inducing the most significant changes, followed by varying responses from CPPF and RF. When using RTPF for CPB reinforcement, emphasis should be placed on enhancing technical indicators related to viscosity such as energy consumption and pipeline wear during pipeline transport. Furthermore, adjustments were necessary to account for flow curve instability resulting from interactions between fibers and the paddle, with the data aligning well with the Bingham model. The addition of fibers, particularly CPPF and RF, primarily influenced plastic viscosity rather than yield stress, underscoring the limitations of slump tests in assessing rheology.

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Granulated truck waste tire was first pyrolyzed in a fixed‐bed reactor under an inert atmosphere and at certain conditions. The highest oil yield of which was 47.0 wt %, was attained at 550 and 20°C/min. The oil was separated into a fraction of 150–300°C boiling points, so‐called diesel‐like fuel (DBY), with a calcium oxide (CaO) catalyst at an optimal ratio of 2 wt %. The fraction was subjected to desulfurization, bleaching, and deodorization, respectively, at specific conditions, and this process resulted in a decrease of 75.8 wt % compared to its initial sulfur content of 5000 ppm. The upgraded diesel‐like oil (DAF) fraction contained chemical compounds with carbon numbers C6–C26. In addition, its physicochemical characteristics showed a kinematic viscosity of 3.13 cSt (40°C), a density of 832 g/L (15°C), a lower heating value of 42.32 MJ/kg, and an H/C molar ratio of 1.73. Lastly, the DAF was tested with commercial diesel fuel for its motor and emission performance via a single‐cylinder diesel engine. All in all, it can be said that the DAF may be harnessed as a substitute for diesel fuels after its further upgrading via catalytic hydrodesulfurization etc. [ABSTRACT FROM AUTHOR]

Polymer waste is currently a big and challenging issue throughout the world. Waste tires represent an important source of polymer waste. Therefore, it is highly desirable to recycle functional fillers from waste tires to develop composite materials for advanced applications. The primary theme of this review involves an overview of developing polystyrene (PS) composites using materials from recycled tires as fillers; waste tire recycling in terms of ground tire rubbers, carbon black, and textile fibers; surface treatments of the fillers to optimize various composite properties; and the mechanical, fire retarding, acoustic, and electromagnetic field (EMI) shielding performances of PS composite materials. The development of composite materials from polystyrene and recycled waste tires provides a novel avenue to achieve reductions in carbon emission goals and closed-loop plastic recycling, which is of significance in the development of circular economics and an environmentally friendly society. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The global demand for rubber is on a steady rise, which is driven by the increasing production of automobiles and the growing need for industrial, medical, and household products. This surge in demand has led to a significant increase in rubber waste, posing a major global environmental challenge. End-of-life tire (ELT) is a primary source of rubber waste, having significant environmental hazards due to its massive stockpiles. While landfilling is a low-cost and easy-to-implement solution, it is now largely prohibited due to environmental concerns. Recently, ELT rubber waste has received considerable attention for its potential applications in civil engineering and construction. These applications not only enhance sustainability but also foster a circular economy between ELT rubber waste with the civil engineering and construction sectors. This review article presents a general overview of the recent research progress and challenges in the civil engineering applications of ELT rubber waste. It also discusses commercially available recycled rubber-based construction materials, their properties, testing standards, and certification. To the best of the authors' knowledge, this is the first time such a discussion on commercial products has been presented, especially for civil engineering applications. [ABSTRACT FROM AUTHOR]

This study investigates the effects of varying temperatures on the co-pyrolysis of wood sawdust (WS) and waste tires (WT) within a stainless steel fixed-bed reactor under a nitrogen atmosphere. The experiments were conducted at three different temperatures: 400 °C, 500 °C, and 600 °C, focusing on the thermal behavior and resultant product yields. At 600 °C, WS produced the highest oil yield (63.6 wt%), suggesting a tendency to generate more aqueous and volatile components. Conversely, WT alone showed an optimal oil yield of 46.4 wt% at 500 °C, while the WS-WT blend achieved 55.6 wt%. Gas chromatography-mass spectrometry (GC-MS) analyses of the pyrolytic oils indicated that WS-heavy mixtures were rich in aliphatic compounds, whereas WT-dominant samples had increased aromatic and phenolic contents, demonstrating the potential for creating valuable chemicals from waste. Additionally, gas analysis highlighted significant variations in syngas composition, with increased methane and decreased CO2 levels at higher temperatures, emphasizing the role of the water-gas shift reaction. These findings underscore the critical importance of temperature control in optimizing the efficiency and quality of products from co-pyrolysis, presenting a viable method for enhancing the value derived from waste materials.

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The global scientific research circle and government agencies face a number of serious environmental challenges, one of which is the recycling of “End of Life Tires” (ELT). An estimation of one billion tires is expected to end their useful life annually, of which only roughly 50% are recycled at the moment, with the remainder ending up in landfills. Consequently, to solve this gap in the ELT's utilization rate, it is imperative to enhance the current application and furthermore create new applications for recycled tire materials. One of such areas that is currently being investigated is the introduction of waste tire into concrete as partial replacement of natural aggregates in concrete production. Despite its great prospects, it has drawbacks such as lack of proper bonding with the cement matrix and weak rubber intrinsic strength, which make it unsuitable for widespread usage as an aggregate. To get past this obstacle, numerous rubber treatment techniques that enhance the mechanical characteristics of rubber concrete remarkably as well as the bonding properties have been studied by researchers. The impact of rubber percentage replacement, rubber aggregate size and different treatment techniques on various mechanical characteristics of rubber concrete are examined in this review paper. But in order for the concrete industry to embrace it, the researchers need to devise a rubber treatment technique that can tackle the issues of high combustible and the harmful gases that are released from the rubber aggregates when they come in contact with fire.

A highly efficient eco-friendly nanoadsorbent i.e. γ-Fe2O3/MWCNTs/Cellulose was derived from waste tires and natural cellulose for malachite green removal from aqueous solutions through a chemical vapor deposition technique. The properties of the synthesized nanoadsorbent were identified using XRD, FESEM, EDX, TEM, EDS, DLS, FTIR, VSM, BET, XPS, and TGA. According to the results, the highest malachite green adsorption capacity was obtained by γ-Fe2O3/MWCNTs/cellulose 47.61 mg/g. In addition, the amount of dye adsorption increased with decreasing flow rate and enhancing column length from 9 to 3 mL/min and 2 to 10 min, respectively. The pseudo-second-order and the Langmuir model were the best kinetic and isothermal models to describe the malachite green adsorption process (R2 > 99%). The thermodynamic results demonstrated that the adsorption process is exothermic and spontaneous. However, after 4 consecutive adsorption/desorption cycles, the removal efficiency was 87.35%. Therefore, γ-Fe2O3/MWCNTs/Cellulose can be considered as an outstanding adsorbent for malachite green removal. [ABSTRACT FROM AUTHOR]

Ethanol gasification of waste tires was investigated against pyrolysis in the presence of H-β zeolite and γ-Al2O3 catalysts. Non-catalytic gasification gave a much higher gas yield of 45.2% in comparison to a pyrolysis gas yield of 29% and increased the hydrogen content of the gas. Using a catalyst increased the gas yield during both pyrolysis and gasification from 29% to 34–35% and 50–52%, respectively. γ-Al2O3 was found to be more effective at catalyzing secondary pyrolysis reactions such as cracking, dehydrogenation, aromatization, and cyclization, especially when coupled with the excessive free radicals produced during ethanol gasification, resulting in a gas with 35 mol% hydrogen. H-β was found to enhance the formation of light alkenes such as propylene and ethylene during pyrolysis and gasification, respectively. The resultant syngas is suitable for use either as an energy alternative, or as feedstock for Fischer-Tropsch synthesis for the production of higher hydrocarbons. • Catalytic gasification of scrap tires with ethanol increases gas yield to 50–52%. • Gasification with γ-Al 2 O 3 catalyst enhances production of hydrogen. • Gasification with H-β zeolite enhances production of ethylene. • Thermal gasification produces gas with H 2 /CO ratio suitable for Fischer-Tropsch and methanol synthesis. [ABSTRACT FROM AUTHOR]

This research aims to assess the rheological and mechanical characteristics of Self-compacting concrete (SCC) incorporating waste tire rubber aggregates (WRTA) as an interim substitute for coarse aggregates. However, the standard experimental modeling approach has significant obstacles when it comes to overcoming the nonlinearity and environmental susceptibility of concrete parts. Therefore, linear regression (LR) and extreme gradient boosting (XGBoost) were used as two standard single machine learning (ML) models to predict the aforementioned rubberized SCC features. In this study, conventional coarse aggregates were supplanted with WRTA at 0%, 5%, 10%, and 20% to uncover the optimal proportion of coarse aggregates substituting rubber. To find the optimum amount of WRTA to use as a substitute, the study follows the impacts of rubber on the self-compacting rubberized concrete's (SCRC) rheological and mechanical characteristics. The consequences on fresh properties were investigated by the slump flow, J-ring, and V-funnel tests, while compressive and splitting tensile strengths tests were conducted to assess mechanical properties. Increasing WRTA test outputs indicated a deterioration in workability and hardened qualities. While a 10% swapping ratio is deemed feasible for producing SCRC, optimal results were achieved by reducing environmental impacts and efficiently managing a significant volume of rubber tire waste with a 5% substitution of rubber within the coarse aggregates. The research findings indicated a noticeable decrease in fresh properties as the WRTA content increased. Notably, after 28 days, a 10% WRTA substitution led to a 34% reduction in compressive strength and a 28% decrease in splitting tensile strength, satisfying ACI standards. Furthermore, XGBoost demonstrated superior predictive performance with the highest R2 values, outperforming the LR model and affirming its efficacy in delivering more accurate predictions.

Polymer waste is currently a big and challenging issue throughout the world. Waste tires represent an important source of polymer waste. Therefore, it is highly desirable to recycle functional fillers from waste tires to develop composite materials for advanced applications. The primary theme of this review involves an overview of developing polystyrene (PS) composites using materials from recycled tires as fillers; waste tire recycling in terms of ground tire rubbers, carbon black, and textile fibers; surface treatments of the fillers to optimize various composite properties; and the mechanical, fire retarding, acoustic, and electromagnetic field (EMI) shielding performances of PS composite materials. The development of composite materials from polystyrene and recycled waste tires provides a novel avenue to achieve reductions in carbon emission goals and closed-loop plastic recycling, which is of significance in the development of circular economics and an environmentally friendly society.

Artificial stones are building materials developed with stony waste aggregates and a polymeric resin as an agglomerate. Its mechanical properties, in general, overcome natural stone's properties, since the use of resin makes it possible to manufacture a less porous, that is, a denser material, more impermeable, and with greater mechanical resistance. However, its development is costly because it requires the use of high-quality aggregates. Waste can replace these aggregates, developing an economically and environmentally advantageous novel, sustainable artificial stone. This work's main goal is to develop a flexible sustainable artificial stone based on waste glass and waste tire agglomerated with a biopolymeric resin, polyurethane from castor oil, and evaluate its properties. Plates were manufactured with 22% of polyurethane resin and 78% of different proportions of the two wastes (glass and tire) mixed up. The molding was carried out under a 600 mmHg vacuum, a 6Hz vibration, and an 80° hot pressing for 20 min. The stones developed, named AS50GT and AS66GT, were lighter than other developed artificial stones, but less resistant to bending efforts since rubber tire is a polymeric material. However, they displayed a high Izod impact strength, evidencing that the development of artificial stones with glass and tire wastes and biopolymeric polyurethane resin is viable, not only from an economic and environmental point of view but also technically viable once both developed stones can be marked in the building construction industry.

A planetary ball mill was used to treat the pyrolytic carbon black (CBp) of waste tire by dry modification with 3 types of modified resins, PA, PF-203 and Polstal-PC as the modifiers, the changes of physico-chemical properties and structure of CBp before and after modification were explored, and the effects of modified CBp on curing characteristics, cross-linking density, mechanical properties and dynamic mechanical properties of natural rubber were investigated. The results showed that the particle size of CBp decreased with the extension of milling time. The mo-dified resin Polstal-PC had the most obvious grinding effect, and compared with unmodified CBp, the total specific surface area of CBp modified by Polstal-PC increased from 65.1 m2/g to 97.4 m2/g and the specific surface area of the outer surface increased from 63.0 m2/g to 71.6 m2/g. All of the 3 type of modifiers contributed to vulcanization of natural rubber, and CBp modified by Polstal-PC could significantly improve tensile strength, modulus at 300% and cross-linking density of natural rubber vulcanizate, and the addition of CBp modified by tackifying resin PA could cause the decrease of modulus and cross-linking density. CBp modified by Polstal-PC had the best enhancement effect on natural rubber, and natural rubber vulcanizate showed the best comprehensive performance when the addition amount of CBp modified by Polstal-PC was 2 phr (mass, similarly hereinafter), and as far as CBp modified by Polstal-PC was concerned, the improvement of rolling resistance of natural rubber vulcanizate was better than the loss of wet skid resistance. However, storage modulus of natural rubber vulcanizate increased significantly when the addition amount of CBp modified by Polstal-PC was more than 3 phr.

End-of-life tires are a common and hazardous type of waste. According to estimates, over 2 billion tires are produced each year, and all of these tires will eventually be discarded as waste. Landfilling waste tires is strictly prohibited by the regulations of the European Union and the Environmental Protection Agency; they should be retreated and reused in an alternative scenario. As a waste-to-energy technology, pyrolysis can emerge as a useful technique to thermally degrade waste tires and produce useful byproducts in the form of liquid, gas, and char. The derived products can be filtered and used in further industries as biofuel substances. Pyrolytic oil has a high calorific value of 35–45 MJ/kg and can be used as an alternative to diesel to fuel specific vehicles. However, the environmental footprint of the technology has been widely neglected when using waste tires as feedstock. Made from synthetic and natural rubbers, tires contain a high amount of sulfur and styrene, which can cause toxic emissions and negatively affect the environmental sustainability of pyrolysis. This concept paper aims to elaborate the parameters of an operating rotary kiln reactor by reviewing previous life cycle assessment studies and applying the methodology to an industrial-scale pyrolysis plant in Northern Cyprus. Results found a maximum production yield of 45.6% oil at an optimal temperature of 500 °C. Influential parameters such as temperature, residence time, and heating rate are reviewed based on their overall contribution to the production yield and the environment. The outcome of this paper emphasizes the need in the literature to apply environmental analyses to industrial and commercial-scale reactors to test the sustainability of using pyrolysis as a tire waste management strategy. In addition, complex engineering concepts and tasks in waste recycling will be discussed in a broad and accessible manner, with the implications and future work discussed. [ABSTRACT FROM AUTHOR]

The influences and disciplines of pyrolytic condition for recycle BTX products from Passenger-Car-Waste-Tire. [Display omitted] • Prediction models for yields of oil and BTX from PCWT cracking are established. • Optimum pyrolytic parameters for BTX formation are investigated. • Influencing mechanisms of pyrolytic conditions on BTX formation are elucidated. Pyrolysis is an effective method for waste tire disposal. However, it has rarely been used to recycle specific highly valuable components (such as benzene, toluene, and xylene (BTX)) from tire rubbers, owing to complicated pyrolytic reactions. This study investigated the pyrolysis process of passenger-car-waste-tires (PCWT) with the help of TG–DTG and Py–GC/MS. Based on response surface methodology (RSM), the effect of pyrolytic parameters on the yields of pyrolytic oil and BTX is evaluated. Furthermore, the BTX generation mechanisms are discussed from the perspective of aliphatic and aromatic hydrocarbon transformations. Additionally, pyrolytic conditions including temperature, rubber particle size, pressure, and gas flow rate were systemically investigated and the optimum pyrolytic condition for yield of BTX (26.5 g per 100 g tire rubber) was obtained [765 K, 0.7 mm, 0.52 MPa and 2.5 mL (g min)−1]. Therein, yield of benzene, toluene and xylene were 1.07, 5.03 and 20.40 g per 100 g tire rubber, respectively. During PCWT pyrolysis, BTX is primarily obtained via the Diels–Alder reactions of small-chain alkenes and transformations of limonene and aromatics. This study elucidates the BTX generation mechanisms during PCWT pyrolysis and clarifies the effects of varying pyrolytic conditions on BTX generation. [ABSTRACT FROM AUTHOR]

The influences of acidic (HZSM-5) and basic oxide (CaO/MgO) catalysts and their combinations on yield and quality of pyrolytic oil, derived from co-pyrolysis of rice straw (RS) and waste tire (WT), were investigated. The pyrolytic oil from non-catalytic co-pyrolysis of RS/WT was found to have 31, 27, and 36 peak area% of monocyclic aromatic hydrocarbons (MAHs), aliphatic hydrocarbons, and oxygenates, respectively. The yield of MAHs was increased by 43.63% for RS/WT/HZSM-5 while that of oxygenates was decreased by 55.56%. Superior surface area, abundant acidic sites, and selectivity of HZSM-5 towards aromatics render it more efficient than either of metal oxides catalyst (CaO/MgO) alone. Dual-catalyst bed of HZSM-5/CaO at mass ratio of 1:1 was superior to all other combinations with MAH yield of 59 peak area% while the selectivity of benzene, toluene, and xylenes (BTX) at the same ratio was 18.79%, 33.81%, and 41.85%, respectively. Similarly, the optimum combination of HZSM-5/MgO was also 1:1 which was as equally efficient in deoxygenation as HZSM-5 alone. Moreover, all combinations of HZSM-5/CaO were superior in the terms of HC production and deoxygenation compared to their respective mass ratios of HZSM-5/MgO. Additionally, the application of a dual catalytic bed significantly upgraded the calorific value (HHV) and other physico-chemical characteristics of pyrolytic oil. [ABSTRACT FROM AUTHOR]

Hardpan is one of the major problems found in many parts of Thailand where monocropping and repeated plowing at the same depth are conducted. This work aimed to study the feasibility of using crumb rubber produced from waste tires to alleviate the soil compaction problem. Effects of particle size and loading of crumb rubber on the degree of soil compaction were investigated. The quality of water extracted from crumb rubber was also analyzed to determine the severity of environmental contamination. The scope of work was further extended into field tests. The results reveal that the addition of crumb rubber into sandy loam subsoil significantly reduced the bulk density of the compacted soil and permitted greater water permeation through the compacted soil layer. The effects were more pronounced with either increasing crumb rubber loading or reducing crumb rubber particle size. For the field test, the addition of small crumb rubber (S-crumb) at 30%wt. resulted in a significant reduction in penetration force in conjunction with a considerable increase in water permeability. The results clearly confirm the reduction in soil compaction by the addition of crumb rubber. From a quality analysis of the extracted water, most poisonous heavy metals were below the detection limits of the test equipment, except zinc. [ABSTRACT FROM AUTHOR]

Waste tires are also known as "black pollution", and pose significant risks to human health and ecosystems. The pyrolysis process can recover valuable products such as natural gas, oil, and pyrolysis carbon black (CBp), with CBp being the most important one. However, CBp from waste tires has a high degree of particle aggregation and low oil absorption value, making it difficult to further utilize. In this work, we propose a novel method to activate CBp by simulated fuel gas, which fully utilizes exhaust gas resources and enables the reuse of resources. The simulated fuel gas, composed of a mixture of N2 and CO2, was used to investigate the effects of activation temperature (700–1000 °C), activation time (2–5 h), flow rates (30–50 mL·min−1), and the content of CO2 in the simulated fuel gas (10%-90% (volume)) on increasing the specific surface area. The samples were analyzed using XRD, SEM, N2 adsorption/desorption, and Raman shift. The results indicate that the hybrid atoms and carbon atoms in CBp can absorb enough energy to open the closed pores, allowing the activator to fully react with CBp. This work demonstrates a feasible approach to improve the high value-added utilization of cracked carbon black. [ABSTRACT FROM AUTHOR]

The main aim of this research is to investigate and mathematically express the relationship between the mixture proportions of rubberized concrete and its thermal conductivity performance. For that purpose, a dataset with a wide range of experimental variables was compiled from the studies available in the literature and one of the most important and widely used machine learning methods, called Artificial Neural Networks, was chosen to establish this mathematical expression strongly and consistently. Two important criteria were taken into consideration when compiling the dataset: firstly, the aggregate had to be of natural normal weight and secondly, the rubber aggregate had to be derived from waste tire and not treated. A reliable, functional, and robust empirical model to estimate the thermal conductivity coefficient of the rubberized concrete was generated in the scope of this study based on the input parameters like cement content (c), water-to-cement ratio (w/c), natural aggregate-to-cement ratio (na/c), rubber aggregate-to-cement ratio (ra/c), and rubber type (rt). The estimation capability of the model was validated using a dataset that the model never faced and was evaluated based on some statistical metrics like R2, MAPE, MSE, etc. The R2, MAPE, and MSE values of the trained model were about 0.984, 4.62%, and 0.002, respectively. Both validation and statistical evaluation results revealed that the model can accurately and reliably estimate the thermal conductivity coefficient of the rubberized concrete. Besides, the statistical metrics of the developed model were in the acceptable range for such models. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of oil shale pyrolysis and the utilization value of semi-coke, this paper co-pyrolyzed Huadian oil shale and waste tire.The weight loss behavior, product yield and composition properties of co-pyrolysis were investigated by thermogravimetric analyzer and aluminum retort reactor.The synergistic effect was analyzed based on the difference between experimental and calculated values.The results show that co-pyrolysis can promote the release of volatile matter, the actual weight loss is higher than the calculated value at 500 ℃, and reaches the maximum value of 2.86 % when the proportion of waste tire is 80 %.The mixed pyrolysis of oil shale and waste tire has the effect of "increasing oil and reducing water".When the waste tire accounts for 50 %, the actual oil yield is 32.91 %, which is 1.5 % higher than the calculated value, and the actual water yield is 1.20 % to 1.77 % lower than the calculated value.Meanwhile, the content of heavy components with boiling point higher than 350 ℃ in the pyrolysis oil increases.There is higher yield of C1~C4 hydrocarbons from waste tire pyrolysis, and the calorific value of semi-coke is up to 30.43 MJ/kg.Co-pyrolysis can also improve the calorific value of pyrolysis gas and semi-coke.

Recycling end-of-life tires is a global problem that requires an urgent solution. Storing and preserving these tires is a challenge that delays facing potential problems instead of solving the problem. In this context, recycling waste tires without harming the environment and at low costs has been the focus of many researchers. For a few decades, the possibility of these tires to be granulated to the size of aggregate for concrete and then be replaced with natural aggregate has been a subject of research by scientists studying in this field. In this regard, this study aims to experimentally investigate the influence of waste rubber aggregate on some engineering properties of concrete, such as, ultrasonic pulse velocity-based quality assessment, abrasion resistance, and thermal conductivity characteristics as well as the mechanical performance, namely, compressive strength. Another significant side of the study was to establish a statistical relationship and correlation between the w/c ratio and substitution level of waste rubber aggregate and the experimental outputs. The experimental study indicated that the waste rubber aggregate decreased the compressive strength of the concretes whereas it improved the thermal conductivity characteristics and abrasion resistance of the concretes manufactured in this study. On the other hand, the statistical analysis revealed that the input parameters have meaningful effects on the engineering properties of the concretes, and there is a strong correlation between these properties.

This paper presents the effects of waste tires, water content, and relative density on the soil dominant frequency based on experiment. Cylindrical molds with a diameter of 30 cm and height of 50 cm are prepared to understand the effects of these materials. The molds are filled with sand at different relative densities (60% and 80%). In addition, samples are prepared by adding waste tire particles at different rates (0%, 0.5%, 1%, and 2%) to the sand to achieve different relative densities and water contents (0%, 5%, 10%, and 15%). The soil dominant frequency and horizontal/vertical (H/V) amplitude are determined using the microtremor technique by measuring each cylinder for 60 min using a broadband seismometer. Microtremor data are analyzed using the H/V spectral ratio (Nakamura) method. The experimental result shows that the waste tire particles added to the sand decrease the H/V amplitude. The most suitable environment features a relative density of 60%, which is achieved using 1% waste tires and 0% water content. Meanwhile, the most suitable environment has been achieved using 0% water content and 0.5% waste tire ratio for 80% relative density. Using the prepared composite material with waste tires as an additive on the soil may reduce the destructive effects of earthquakes. [ABSTRACT FROM AUTHOR]

Waste incineration is a widely used treatment method, and sustainable approaches are required to properly recycle large volumes of incineration ash to reduce environmental impacts and landfill space consumption. Studies have focused on the potential of recycling incineration ash as a replacement for natural aggregates in civil engineering applications, such as road construction. However, industrial waste incineration ash, such as waste tire incineration ash, contains hazardous heavy metals, such as lead and zinc that pose potential environmental threats. Moreover, few studies have investigated the leachability of these hazardous metals after long-term natural aging. This study investigates the long-term evolution of leachate chemistry, mineralogical transformation, and heavy metal fixation performance of a recycled roadbed material using ash from industrial waste incineration of waste tires and biomass (SFA). Additionally, field samples from a five-year pilot test site utilizing SFA were also examined. Regulatory leaching tests showed that the concentrations of Cd, Pb, As, T-Cr, and Ni were all below permissible limits even after five years of utilization. Long-term column leaching experiment results indicated that, compared to the total content of the SFA material, the leaching ratios of Pb, T-Cr, Cu, and Zn were 27%, 12%, 5%, and 0.1%, respectively. The SFA pH-stat leaching test results demonstrated that the mass release of the total content of heavy metals was relatively minimal, even under acidic pH conditions (pH < 4). Finally, profiles of pH and major ions in leachate from the column leaching experiment were simulated using HYDRUS HP1, implementing a dual-porosity modeling approach. In conclusion, despite containing hazardous heavy metals, SFA exhibits significantly low leaching rates over a long-term period. [ABSTRACT FROM AUTHOR]

One of the most severe environmental problems in the world is how to dispose of waste tires properly. Many tires are dumped or thrown away worldwide every year, severely threatening the environment. Most waste tires are used as fuel by some industries, but as we know, this type of waste use has a dangerous effect. The use of synthetic fibers, especially industrial steel fibers, which is very common today and requires high raw materials and energy, negatively impacts the environment by emitting CO2 during manufacturing. Therefore, finding fibers that perform similarly to industrial steel fibers is essential. This article presents a comprehensive overview of the methods of recycling steel fibers from waste tires, the characteristics of recycled fibers, and their application in producing different cement-based composites. The effect of these recycled fibers on fresh concrete properties, including workability and porosity, has been investigated. The effect of these fibers on the concrete's mechanical characteristics, including compressive strength, splitting tensile strength, flexural strength, impact resistance, and durability, is also discussed. According to recent research, using recycled steel fibers to strengthen concrete can be a suitable alternative to industrial steel fibers, which have fewer adverse effects on the environment and reduced recycling costs. [ABSTRACT FROM AUTHOR]

Waste tire disposal is a growing challenge among major cities worldwide because each year, a huge number of end-of-life tires is generated. The current study aimed to evaluate the potential of ground rubber tire (GRT) and waste rubberwood sawdust (RWS) as materials for developing wood-polymer composites (WPCs). The effects of the compositions' contents and rubber types on the mechanical and physical properties, as well as the morphology of the thermoplastic elastomer (TPE)/RWS composites were investigated. The results revealed that the addition of about 30–60 wt% of RWS improved the modulus of elasticity, compressive modulus, and hardness of the TPE composites based on both the GRT and natural rubber (NR). With the same RWS content and rubber type, the TPE/RWS composites with rubber/plastic blends of a 30/70 ratio clearly yielded better mechanical and physical properties than those blends with a 40/60 ratio. The addition of about 2–4 wt% of maleic anhydride-grafted polypropylene (MAPP) improved all the properties of the TPE/RWS composites. Overall, the composites based on the GRT gave superior strength, rigidity, and dimensional stability than that based on NR. It is therefore suggested that the eco-friendly TPE composites made from GRT and waste rubberwood could be a suitable replacement for the inorganic filler-natural rubber composites for saving costs and the environment. [ABSTRACT FROM AUTHOR]

In this study, both mechanical and thermal properties of epoxy@carbon black nanocomposite (EP@CB-NC) produced by adding 0.3, 0.6, and 1% by weight carbon black nanoparticle obtained from waste automobile tires to epoxy were investigated. The chemical and structural composition of EP@CB-NC was characterized by Fourier transform infrared spectroscopy (FTIR) in scanning electron microscopy (SEM). In addition, simultaneous thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) experiments, and thermal conductivity measurements were performed to determine the thermal stability of the prepared EP@CB-NC. Increasing the strength of modified epoxy composites by means of nanoparticles obtained with waste may pave the way for obtaining new materials with clean environment and superior properties. The mechanical and thermal properties were improved by adding carbon black to the bare samples.

A comprehensive study investigating all co-pyrolysis products (bio-oil, char, and gas) utilizing bench-scale reactor is essential for potential use in upscaling and techno-economic analysis for commercialization and integration of pyrolysis with conventional systems. This study explores the co-pyrolysis of rice straw (RS) and waste tire (WT) to assess the impact on products under a broad range of feedstock ratio (20, 40, 60, and 80 wt% of WT into RS) in fixed bed reactor at 550 °C. Results revealed that feedstock mass ratio played a crucial role to transform the oxygenates into hydrocarbons (HCs). Liquid yield, organic phase, pH, aromatics, and olefins increased with increase of WT proportion in blend. Bio-oil yield, aromatics and olefins reached to 45 wt%, 42%, and 30% at WT/RS (80:20) compared to 36 wt%, 2%, and 4% in the case of RS alone, respectively. Likewise, at the same blend ratio, 85% reduction in oxygenates was observed while higher heating value (HHV) of bio-oil (41.40 MJ/kg) was comparable to that of WT (41.50 MJ/kg). Significant positive synergy was achieved for non-condensable gas after incorporation of WT into RS. Hydrogen (H2) and methane (CH4) along with higher HCs were increased while oxides of carbon reduced with the addition of WT compared to RS alone. Char characteristics also improved with addition of WT into RS in terms of increased carbon content, HHV, and reduced ash content. [ABSTRACT FROM AUTHOR]

This study characterizes the leaching behavior of fuel raw boiler fly ash (BFA) and cement-solidified/stabilized raw boiler fly ash (SBFA). X-ray diffraction analysis shows that the mineral composition of BFA is made up of anhydrite, calcite, and calcium silicate, whereas the composition of SBFA consists of quartz, calcium aluminum silicate, gypsum, and calcite. To verify the environmental impact of utilizing the SBFA material as a road base aggregate, standardized regulatory batch leaching tests are conducted on the SBFA sample, and the results indicate that the concentrations of Cd, Pb, As, Cr, and Ni are below the limits of determination, respectively. The column leaching tests results suggest that mineral solubility is the main factor affecting the release of major elements. Results of pH-stat tests show a decrease in the released-heavy-metal concentration even in extreme acid conditions (pH < 4) for the SBFA sample. Geochemical speciation modelling is performed on the leachate analysis results of the column experiment with PHREEQC. The results indicate that the main mineral composition of the SBFA material under the experimental conditions might consist of calcium compounds such as ettringite, portlandite, gypsum, and anhydrite. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) is an oxidized form of graphene, laced with oxygen‐containing groups. In recent years, the cost‐effective and efficient synthesis of GO remains a significant issue. Hummer's method has become popular due to its simple top‐down synthesis, however, there is an issue due to the release of nitrate gaseous which is harmful to the environment. This research is carried out using regenerated carbon from waste tire as a source of synthesize process through the Hummers Method (HM) and Improved Hummers Method (IHM). The Raman peaks of IHM GO show that the D band and G band are at 1369.12 and 1583 cm−1, respectively and the intensity ratio of the D band relative to the G band (ID/IG) is 0.84. The morphology and structure of graphene oxide show that a nanosize particle stalked together on the surface of the sample structure, bumping pieces, and a coarse surface. The elemental composition of carbon (C) is higher than the oxygen (O) element which showed a good composition of graphene oxide. The XRD spectroscopy indicates the crystal structure of the material and the interlayer spacing between the material and atoms. In this study, the improved method is used by replacing sodium nitrate (NaNO3) with phosphoric acid (H3PO4) during the synthesis process to help increase interlayer distance and helps oxidation on the basal planes. This result confirms that the graphene oxide can be synthesized from regenerated carbon from waste tire using an improved Hummer's method. [ABSTRACT FROM AUTHOR]

Link for citation: Larionov K.B., Gubin V.E., Gorshkov A.S. Waste tire steam pyrolysis kinetic. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 6, рр.204-212. In Rus. The relevance of the study is determined by the long-term and consistently high level of tire waste formation. In addition, the amount of recycled tires in Russia is currently smaller compared to countries with high environmental culture. There are statute recommendations on the involvement of secondary raw materials in the manufacturing sector. A possible method for recycling waste tires by steam pyrolysis is proposed, which provides obtaining valuable products in the form of oil and carbon residue. The paper presents a comparison of the processes of steam and oxygen-free (argon) pyrolysis in terms of the values of formal kinetics, which can be used in the development or modernization of industrial equipment. The aim of the research is to determine the activation energy of waste tire decomposition in inert argon medium and in superheated steam medium. Objects: waste tire granulate from extra-large. Methods: thermogravimetric analysis, proximate analysis, in-line gas analysis, Ozawa–Flynn–Wall method, Friedman method, Kissinger–Akahira–Sunosse method. Results. According to the data of thermogravimetric analysis, the values of the parameters of thermal decomposition were determined. With an increase in the heating rate, regardless of the type of medium, the following was observed: clear increase in the maximum mass loss rate, larger mass of the pyrolysis residue, and a shift of the process to a high-temperature region. The use of steam as an inert agent provides a more intense and uniform process at a typical temperatures lower by 75–90 °C. Using isoconversional calculation methods (Friedman, OFW, KAS), the values of the activation energy for the decomposition of a used tire sample in argon and steam mediums were determined. The average activation energies in argon and steam were 98,9 and 268,4 kJ/mol, respectively.

The recycling of some of the waste is an important issue and very necessary to protect the environment and provide new sources of supply of raw materials. In this experimental research, a solution is suggested to recover the bulky waste, like the waste tire, in the form of aggregates used in the concrete industry. The work performed consists in incorporating used tires as aggregates by partial replacement of the sand in the preparation of sample mortars using different percentages of substitutions in volume varying from 0% to 50%. Physico-mechanical tests were carried out on the mortar mixes. The results obtained show that the use of waste tires as aggregates in the production of mortars can solve several problems related to their disposal and save natural resources related to the extraction of aggregates. Also, the results found show that the waste tires can be used to produce mortars employed for structural and non-structural applications. [ABSTRACT FROM AUTHOR]

Getting rid of plastic and rubber waste is one of the goals of achieving a sustainable lifestyle. Out-of-service tires and fuel and water tanks manufactured from polyvinyl chloride (PVC) are the most common waste that cities suffer from. This paper aims to investigate the effect of reinforced waste polymer particles on the polyester resin matrix when producing polymer matrix composite materials from waste tires and damaged plastic water tanks with different polymeric percentages. The polymer matrix composite could be used later in different applications, such as insulators and vibration dampers. The composite materials were evaluated by measuring the Shore D hardness, tensile strength, modulus of elasticity, and coefficient of thermal conductivity. The overall results showed hopeful behavior. Mixing a specific mixture of waste PVC and tires with polyester and hardener gives a higher tensile strength, modulus of elasticity, and Shore D hardness compared to each material when used separately. The thermal conductivity values increase with the mixing conditions between the materials. The thermal conductivity values can be reduced by using higher percentages of a mixture of waste tires and polyester or PVC and polyester. A 4.5% PVC, 4.5% tire and 91% (polyester and hardener) mixture can be recommended to improve tensile strength performance. A mix of 8.3% PVC, 8.3% tire, and 83.4% (polyester and hardener) can be recommended for high hardness. [ABSTRACT FROM AUTHOR]

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