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The aim of this research was to better understand the influence of adding waste rubber in cement bound aggregate (CBA) by testing both the unconfined and triaxial stress state. CBA with waste rubber was tested in this manner aiming to analyse influence of the confining pressure on the material behaviour. The results indicate that adding 20% rubber to a high cement content mix can assimilate the high stiffness caused by the high cement paste content, resulting in a mixture with increased cement paste content to facilitate in situ compaction. Additionally, a low confining pressure of 40 kPa has the most impact on the elastic properties/stiffness and it would be more appropriate to measure the CBA elasticity modulus with moderate lateral (confining) pressure. Finally, the practical implication of this research is that, in pavement mechanistic-empirical design, a correction of the measured uniaxial static modulus of elasticity by 10–15% should be adopted. [ABSTRACT FROM AUTHOR]

Herein, it is aimed to investigate the effect of zeolite catalyst on the co‐pyrolysis process of waste tyre and poplar wood. A laboratory‐sized reactor is used to pyrolyze 15 g of sample at 500 °C under atmospheric pressure. In the results, it is indicated that co‐pyrolysis affects the properties of the products. Comparing to single feedstock, the co‐pyrolysis enhances the yields of bio‐oil, while reducing the formation of char. The pyrolysis of poplar wood produces 23.3 wt% of bio‐oil, while the pyrolysis of tyre yields 25 wt% of bio‐oil. However, it is 31.29 wt% for the co‐pyrolysis process. Higher content of valuable compounds are formed in the bio‐oil, which improve the fuel properties of the bio‐oil. The zeolite catalyst alters the characteristics of the products obtained from the co‐pyrolysis process. The gaseous products show a decrease in the concentrations of carbon monoxide and carbon dioxide when the catalyst is present. The liquid product analysis reveals the presence of light aromatics such as ethyl benzene and light linear compounds such as alkanes including octane, hexane, etc. The analysis of the catalysts suggests that a very small amount of coke deposits on the catalyst due to the slight increase in carbon content. [ABSTRACT FROM AUTHOR]

Recently, recycling of waste vehicle tyres which pose a significant risk to environmental health has become an important research issue due to environmental concerns worldwide. To handle the waste tyre pollution problem, recycling waste into new products and using waste to improve other materials’ properties can be considered. Waste vehicle tyres can be used in the production of energy and various materials, providing economic and environmental advantages. In this study, experimental studies were carried out on the use of waste tyre steel fiber (WS) obtained from the recycling of heavy vehicle tyres in concrete, including the goal of recycling and reducing the need for raw materials. In one experimental group, waste tyre steel was added to concrete at 0.4% by volume instead of fine aggregate, while in the other experimental group it was added at 0.8% by volume. In the study, in addition to mechanical analyses, many microanalysis experiments were carried out to understand whether there was a strong relationship between the results. The study was conducted at target temperatures of 400, 600 and 800 °C depending on the fire scenario for building and construction materials according to ISO 834 and ASTM E119 standards. Compressive strength losses and characterization changes in 15 cm cube plain concrete and composite concrete specimens exposed to targeted high temperatures for 60 minutes were compared in terms of strength. Ultrasonic pulse velocity (UPV), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis was also performed, as it was understood that there was not enough data in the literature regarding waste tyre steel fiber reinforced concrete. General results showed that fiber-added concrete made significant contributions to concrete performance at high temperatures.

• Infrared heating and TG-FTIR help study cross-interaction of co-pyrolysis volatiles. • Infrared heating reduced CO 2 emission, oxygenated compounds, improved tar quality. • Rising temperature and infrared heating aid in aromatizing D-limonene intermediates. Using fast infrared heating technology to minimize the pyrolysis temperature differential and optimizing secondary reactions is advantageous for studying co-pyrolysis behaviors. In this study, the co-pyrolysis behaviors of waste tyres (WT) and corn stover (CS), including product distribution, pyrolysis kinetics, and thermodynamics, were studied using TGA-FTIR analysis and fast infrared heating reactor. The DTG curves for the co-pyrolysis of WT and CS significantly differed from the calculated values, implying that the pyrolysis intermediates produced by CS during the pyrolysis process may have synergetic effects with the pyrolysis of WT. The apparent activation energies using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were similar, 244.88 kJ/mol and 245.93 kJ/mol, respectively. The experiment results suggest that the bio-oil yield increased first and then decreased with a further temperature increase. The yield of bio-oil gradually increased from 35.36% to 46.06% as temperature rose from 500 °C to 700 °C; but the further increasing to 800 °C decreased the bio-oil yield to 40.72%. The aromatic compounds in tar gradually increased with increasing the temperature, while the aliphatic compounds increased initially and then reduced. Meanwhile, the oxygenated compounds first decreased and then increased with increasing the pyrolysis temperature. The yield of light oil components (C＜10) increased from 5.11% at 400 °C to 7.71% at 700 °C. A further increase in the pyrolysis temperature to 800 °C reduced the light oil content to 4.93%. [ABSTRACT FROM AUTHOR]

Syntactic foams, containing up to 23 wt% of untreated waste tyre-derived rubber particles mixed with hollow glass microspheres (HGMs) and epoxy, were produced via compressed air-assisted injection moulding. This study investigated the effect of rubber particles on the through-the-thickness compression properties and the vibration-damping response of the ternary syntactic foams. The interaction between foam constituents was investigated using SEM, with the objective to establish a microstructure-compression property relationship for rubber-incorporated foam. The effect of rubber particles on the energy absorbed by the foam under compression deformation was also studied. The substitution of epoxy for rubber particles did not alter the compression properties (crush behaviour) of the foam. A laser Doppler vibrometer was used to measure the vibration-damping response and natural resonance frequency. The vibration-damping ratio of the rubber-incorporated foam increased by up to 75% upon the addition of 23 vol % rubber particles.

Abstract Environmental contamination of rubber from waste tyres poses a risk to the environment. Rubber particles from tyres enter the environment due to the abrasiveness of the road surface. The aim of the scientific work was to observe the biological degradability of waste tyres in aquatic environment and its ecotoxicity. Biodegradability was observed under aerobic and anaerobic conditions that simulate both aerobic and anaerobic conditions in the aquatic natural environment. Aerobic conditions in the aquatic environment take place in flowing fresh water, sea water, lakes. Leachate was prepared to simulate the behaviour of tyres in an aqueous environment. Aerobic degradability was evaluated through complete biodegradability using a 301 F manometric respirometry test. Anaerobic biodegradability was evaluated by measuring biogas production using OECD 311 Anaerobic Biodegradability of Organic Compounds in Digested Sludge. For a better simulation of the natural environment, the pH of the leachates from the tyres was adjusted to a neutral range. It should be noted that standard degradability tests were extended by 7 days due to low biodegradability. Adjusting the pH during the biodegradability test is also a modification of the original test. This modification was used to better simulate biodegradability when the pH of tyres in the natural environment is reduced by acid rain. An essential part of monitoring the behaviour of waste tyres was the assessment of ecotoxicity using standard tests. The contribution of the scientific article lies in the evaluation of the course of decomposition in aerobic and anaerobic conditions with and without pH adjustment and in the use of modified biodegradability tests. The benefit of the scientific work is in the determination of the biodegradability of waste tyres with and without pH treatment, which simulate a comparison of the degradability of tyres in an acid rain environment. Another benefit of the scientific work is the depiction of biodegradation using 3D modelling with calculations of 100% degradability at different input concentrations of waste tyres. Modelling was used for the time for the absolute decomposition of tyres without pH adjustment (outside the acid rain environment) and with pH adjustment (in the acid rain environment). By monitoring, it is possible to determine whether acid rain as an anthropogenic activity influences the degradability of waste tyres in the natural environment. Biodegradability tests confirmed the low biological degradability of waste tyres. The highest average rate of biological degradability—15% was recorded at the input concentration of waste tyres of 350 mg/L. The aerobic degradability test confirmed the improvement of tyre decomposition when adjusting the pH to the level of 6.5–7.5. On the contrary, the anaerobic degradability test confirmed the improvement of the decomposition in the alkaline region compared to the neutral pH values of the mixture. By mathematical–statistical evaluation of aerobic decomposition with preservation of degradability trends at three input concentrations, the time of absolute decomposition of waste tyre particles at a concentration of 370 mg/L was found to be approximately 336 days. By adjusting the pH to the neutral range during aerobic decomposition, the total decomposition time was reduced to 126 days. The ecotoxicity tests performed confirmed the toxic effect of tyre leachate on selected tested organisms. In the future, the authors propose to focus on a more detailed assessment of the ecotoxicity of the waste conditions and to modify the biodegradability tests by changing the conditions (wider range of input pH value, longer biodegradability time, temperature) for a better simulation of different types of environments. Adjusting the pH to a neutral environment increased aerobic degradability but had no significant effect on anaerobic degradability. Therefore, it is important to focus future research on the adjustment of various conditions to support the degradability of tyres, of which pH has clearly been confirmed as an important factor.

The present research investigates the mechanical and physical properties of recycled aggregate concrete (RAC) modified with micro-silica (MS) and recycled tire steel fiber (RTSF). Natural coarse aggregates (NCA) were completely replaced by recycled coarse aggregates (RCA) to prepare RAC. High-strength RAC mixes were prepared by replacing 5% and 10% of Portland cement with MS. With each level of MS, RTSF was incorporated as 0%, 0.5%, 1 and 2% by volume fraction. In addition to mechanical properties, ultrasonic pulse velocity (UPV), electrical resistivity (ER), and water absorption (WA) of the mixes were also evaluated. The performance of modified RAC mixtures was also compared with plain natural aggregate concrete (PNAC). The experimental investigation revealed that RTSF substantially increased the tensile strength of RAC, whereas MS improved the durability of RTSF-reinforced RAC. RAC made with 1% RTSF and 10% MS showed 54% more splitting-tensile strength compared to the PNAC. The WA capacity of RAC incorporating 10% MS was 15–22% lower than that of the PNAC. [ABSTRACT FROM AUTHOR]

Environmental contamination of rubber from waste tyres poses a risk to the environment. Rubber particles from tyres enter the environment due to the abrasiveness of the road surface. The aim of the scientific work was to observe the biological degradability of waste tyres in aquatic environment and its ecotoxicity. Biodegradability was observed under aerobic and anaerobic conditions that simulate both aerobic and anaerobic conditions in the aquatic natural environment. Aerobic conditions in the aquatic environment take place in flowing fresh water, sea water, lakes. Leachate was prepared to simulate the behaviour of tyres in an aqueous environment. Aerobic degradability was evaluated through complete biodegradability using a 301 F manometric respirometry test. Anaerobic biodegradability was evaluated by measuring biogas production using OECD 311 Anaerobic Biodegradability of Organic Compounds in Digested Sludge. For a better simulation of the natural environment, the pH of the leachates from the tyres was adjusted to a neutral range. It should be noted that standard degradability tests were extended by 7 days due to low biodegradability. Adjusting the pH during the biodegradability test is also a modification of the original test. This modification was used to better simulate biodegradability when the pH of tyres in the natural environment is reduced by acid rain. An essential part of monitoring the behaviour of waste tyres was the assessment of ecotoxicity using standard tests. The contribution of the scientific article lies in the evaluation of the course of decomposition in aerobic and anaerobic conditions with and without pH adjustment and in the use of modified biodegradability tests. The benefit of the scientific work is in the determination of the biodegradability of waste tyres with and without pH treatment, which simulate a comparison of the degradability of tyres in an acid rain environment. Another benefit of the scientific work is the depiction of biodegradation using 3D modelling with calculations of 100% degradability at different input concentrations of waste tyres. Modelling was used for the time for the absolute decomposition of tyres without pH adjustment (outside the acid rain environment) and with pH adjustment (in the acid rain environment). By monitoring, it is possible to determine whether acid rain as an anthropogenic activity influences the degradability of waste tyres in the natural environment. Biodegradability tests confirmed the low biological degradability of waste tyres. The highest average rate of biological degradability—15% was recorded at the input concentration of waste tyres of 350 mg/L. The aerobic degradability test confirmed the improvement of tyre decomposition when adjusting the pH to the level of 6.5–7.5. On the contrary, the anaerobic degradability test confirmed the improvement of the decomposition in the alkaline region compared to the neutral pH values of the mixture. By mathematical–statistical evaluation of aerobic decomposition with preservation of degradability trends at three input concentrations, the time of absolute decomposition of waste tyre particles at a concentration of 370 mg/L was found to be approximately 336 days. By adjusting the pH to the neutral range during aerobic decomposition, the total decomposition time was reduced to 126 days. The ecotoxicity tests performed confirmed the toxic effect of tyre leachate on selected tested organisms. In the future, the authors propose to focus on a more detailed assessment of the ecotoxicity of the waste conditions and to modify the biodegradability tests by changing the conditions (wider range of input pH value, longer biodegradability time, temperature) for a better simulation of different types of environments. Adjusting the pH to a neutral environment increased aerobic degradability but had no significant effect on anaerobic degradability. Therefore, it is important to focus future research on the adjustment of various conditions to support the degradability of tyres, of which pH has clearly been confirmed as an important factor. [ABSTRACT FROM AUTHOR]

Nowadays, waste is something that every country can handle in terms of disposing of it, storing it, or reusing it. However, waste is not only municipal waste but also other raw materials that wear out over time, and their primary purpose in life is over. The ideal case for such waste is its recycling and reuse in other forms. Preventing waste is the best way to recycle, but its life cycle needs to be addressed if waste is produced. The economic model of the current society is primarily linear so far. We extract natural resources and take them to the other side of the world, where products are made from them. These are distributed to other corners of the world, where consumers buy, use and throw them away. This is how waste is created and raw materials in the form of products end up in landfills, incinerators, or thrown in the wild. However, according to the institute, the circular model should, in addition to a stable economy, also ensure a healthy environment. This specific area of waste is under-discussed across society compared to plastics, where more emphasis is placed on recycling and reuse. The presented manuscript concerns the worst kind of waste, namely end-of-life tyres. Despite this, there are companies in Slovakia that are looking for innovative ways to evaluate this type of waste and are dedicated to traditional recycling methods. The number of fast-paced used tyres is increasing nowadays, which also adapts to the lifestyle of everyday life. [ABSTRACT FROM AUTHOR]

Increasing urbanization and development of automobile industry have given rise to an increase in global tyre waste generation. In Australia, it is estimated that around 450,000 tonnes of tyres reach their end-of-life annually and a large percentage of it is disposed to landfill or on-site burial or is stockpiled. This poses a significant environmental and safety risk, since such sites act as a breeding ground for pests and present a significant fire hazard. Hence it is essential to increase the recycling of this hazardous waste. This paper presents a review of the recycling of end-of-life tyres (EOLT) in Australia to produce tyre-derived products (TDPs), which traditionally has been based on mechanical recycling methods (using a series of shredders, screens, and granulators). Key TDPs from Australian tyre recovery include shredded tyres, crumb rubber and baled tyres. There is currently an emerging market in Australia for chemical recycling of tyres, which are typically based on pyrolysis and gasification processes. The produced TDPs have a variety of applications, with key most productive markets being that for crumb rubber in road sprayed seals and rubber granules in soft-fall surfaces and rubber matting in playgrounds and so on. There is a strong emerging market for rubberized concrete, which can be used as lightweight fill and as a drainage medium in landfills. New processing technologies like tyre pyrolysis to generate oil and tyre-derived fuel and also strongly emerging technologies. With a strong push for sustainable design initiatives, TDPs are also being used in permeable pavements, a water sensitive design strategy that is gaining popularity in Australia. [ABSTRACT FROM AUTHOR]

Waste tyre-derived products, including whole tyres, tyre bales, shreds, chips and crumb rubber, have been widely used in geotechnical applications. In particular, tyre bales have considerable potential for use in the construction of a lightweight embankment or road foundation over soft ground, slope stabilisation or landslide repairs and the backfilling for retaining structures. Proper design of tyre bale structures requires a reliable strength analysis to ensure an adequate factor of safety. The analysis should utilise the properties of the tyre bales and the baled structures, which must be properly determined. A laboratory test programme was developed to determine the key strength parameters of a backfill made of tyre bales supplemented with a lightweight aggregate. Full-scale direct shear tests were conducted to define the interface shear strength between the tyre bales and the filling material. Earth pressure reduction analysis based on the experimental results was performed as well to assess the effectiveness of waste tyre bales used as a backfill for rigid retaining structures.

In parallel with the increase in vehicle sales worldwide, waste tires are becoming an increasing problem. The storage and disposal of these waste tires are critical environmental problems. Re-using these wastes in different areas instead of being disposed of is vital in preventing environmental pollution and creating new low-cost products. From this motivation, this paper investigates the properties of traditional reinforced-concrete beam with recycled steel wires (RSWT) obtained from the waste tires. RSWT were added to reinforced-concrete beam between 1% and 3% by weight with an increment of 1%. In total, 9 cubes, 12 cylinders and 12 reinforced-concrete beams were cast and tested to obtain the compressive, splitting tensile and flexural strengths, respectively. RSWT added to the concrete by 1%, 2% and 3% increased the compressive strength by 17.2%, 30.8% and 46.4%, respectively, compared to the reference concrete. In split tensile strength, 14.4%, 25.1% and 36.7% increases were observed, respectively. This showed that there was an effective increase in the compressive and tensile strength of concrete with the increase of fiber content. Although the effect of fiber content in samples with high stirrup spacing (27 cm) provides significant benefit in improving the beam behavior, the effect of fibers was more limited as the stirrup spacing decreased (20 cm and 16 cm). An approximation of over 91% was obtained between the analytical calculations and the experimental results. This shows that the analytical calculations given in the standards can be used for new experimental studies. [ABSTRACT FROM AUTHOR]

Generation of waste has been a significant problem in recent decades in many engineering fields. Self‐compacting rubberized concrete (SCRC) is a new type of SCC, which replaces part of natural aggregates by rubber aggregates in SCC to increase the application range of waste tyre rubber. This study investigates the effect of age and crumb rubber aggregate ratio on fresh and mechanical performance. Eight different SCRC mixtures using 2–5 mm rubber aggregates to replace 10%, 20%, 30%, and 40% natural aggregates by volume respectively, and 5–10 mm rubber aggregates to replace 10%, 20%, 30%, and 40% natural aggregates by volume respectively, are tested after 7, 28, 56, and 91 days for their mechanical properties. Results show that both the compressive and the tensile strength increase with the aging time, both of these properties drop with the amount and size of the crumb rubber content. Similar to compressive and tensile properties, flexural toughness and the modulus of rupture showed increased with the aging time. Small addition of crumb rubber has shown improvements in both rupture and fracture toughness properties, which diminishes when the crumb rubber content becomes significantly large. [ABSTRACT FROM AUTHOR]

• Bibliometric analysis of works on waste tyre gasification. • Simulation of carbon nanomaterials from this process needs investigation. • Polygeneration of products would make the process more effective. • AI applications could be considered in future works. Waste tyres are a significant environmental problem due to their large volume and the difficulty of disposing of them safely. Waste tyre gasification is one of the key thermochemical routes for converting waste tyres into valuable products such as gaseous fuels and/or solid fuels. In this review, a bibliometric analysis of all works on waste tyre gasification from its onset was investigated. We provide an overview of the current state of the art in waste tyre gasification processes, including the types of reactors, gasification modes, and gasification products. The modelling aspect of waste tyre gasification was also investigated as well as its shortcomings. We also discuss the challenges and opportunities associated with the co-production of gaseous products (syngas and hydrogen) and solid carbon products, polygeneration of multiple products, and identify areas for further research. Our review demonstrates that gasification of waste tyres is a viable option for the production of energy and valuable by-products, but more research is needed to optimize the process and improve its economic feasibility. More research is also required in modelling and optimization of other products such as carbon nanomaterials. In addition, the investigation of the life cycle assessment (LCA) of waste tyre gasification is vital as this can ease the adoption of waste tyre gasification technology in developing nations. [ABSTRACT FROM AUTHOR]

Waste Tyres (WT) are a significant fraction of industrial waste and a source of environmental hazards with limited valorisation. To reduce this problem, currently there is a growing interest in valuing the WT through pyrolysis to obtain multifunctional liquids to improve the rheological and self-healing properties of aged binders. This research provides a comprehensive study on using WT mixtures as precursors for asphalt rejuvenators by means of pyrolysis and distillation processes. To this end, WT polymeric fractions from light (WT-L) and mining trucks (WT-M) were used as feedstock and characterised for compositional and thermal properties. Additionally, micropyrolysis coupled with gas chromatography/mass spectrometry (Py-GC-MS) was used to identify the major products in pyrolysis vapours, to elucidate the reaction maps describing thermal degradation of WTs and to predict the feasible reaction conditions. The pyrolysis liquids were produced after a screening of reaction conditions and subjected to distillation, following a response surface model to produce an optimised pyro-rejuvenator. The results showed that the pyrolytic rejuvenator obtained through pyrolysis at 465 °C and distillation cutting at 160–200 °C is mainly composed of hydrocarbons and aromatic substances (95.5%), with a significant proportion of limonene (33.71%). Furthermore, the pyrolytic rejuvenator exhibited highly desirable physical properties in the context of its application and excellent oxidative stability (85.7%). Otherwise, it was determined that bitumen mixtures with 3%–6% doses of pyro-rejuvenator improved the viscosity, softening point, and penetration of aged binders, restoring their physical properties to the virgin state. In conclusion, pyro-rejuvenators can be successfully used as a promising solution to produce more durable and sustainable pavements with improved rheological and healing properties. [Display omitted] • Waste tyres rubber composition was studied through a TGA-kinetic approach. • Py-GC/MS demonstrated a synergistic effect between natural rubber and additives. • Optimal rejuvenator's composition is controlled by coupling pyrolysis with distillation. • Pyro-rejuvenator dosages of 3%–6% are optimal for healing aged asphalts. • Pyro-rejuvenator restores the aged asphalt from PAV to its virgin state. [ABSTRACT FROM AUTHOR]

Waste tyre generation in South Africa is one of the issues that have not found a sustainable solution. Approximately 1.5 billion tyres are produced annually around the world, and South Africa contributes about 11 million tyres accounting to about 177 835 tons of waste annually. Numerous technologies have been used as possible pathways to recycle waste tyres. This review analyzes the main advances in waste tyre pyrolysis and gasification technologies and lists challenges and successes. For waste tyre pyrolysis, recovering high-value products such as limonene, benzene, xylene, and activated carbon can make the process profitable. For gasification, the objective of new studies is for the producer gas to have a desirable composition for further application in the production of chemicals, heat and power and synthesis of liquid fuels. Also, more research is required to fill the gap in the optimum conditions for solar integrated pyrolysis and gasification of waste tyres. A comprehensive comparative techno-economic analysis of chemicals production from waste tyre via gasification is required to determine the most commercially viable route for tyres. [ABSTRACT FROM AUTHOR]

Singeing is a common post slaughtering process of livestock and this has been associated with the introduction of high level of Polycyclic Aromatic Hydrocarbon (PAH) in the meats. There is dearth of information on alternative singeing technology for safe meat. Therefore, this study is aimed at proffering an alternative method for singeing livestock carcass as a post-slaughtering process to reduce accumulation of PAH in meat. An experimental study, involving the use of a singeing device (singeing torch) sourced locally was conducted. Singeing was carried out on a sacrificed goat using conventional methods and the Singeing Torch (ST). Five grams of meat samples singed with kerosene, tyres and the ST were collected from two abattoirs and observed for physical qualities. The physicochemical properties such as pH and PAH were determined using standard procedures. Results were compared with International Agency for Research in Cancer guidelines. Data were analyzed using descriptive statistics and ANOVA at 5% level of significance. Bright appearances with red coloration for ST singed meat while black patches and dull appearances were observed on meat singed with kerosene and tyres respectively. ST singed meat showed a better olfactory quality, a more neutral PH value and PAH of 7.3 and 3.30 (n/ng), while kerosene and tyre singed meat showed 6.8 pH value, 4.20 (n/ng) and 6.61 (n/ng) respectively with mean of 0.194±0.56, 0.248±0.94 and 0.389±1.21 respectively. The principal PAH compounds in ST meat identified were 1-Methylnaphthalene, 2-Methylnaphthalene, Acenaphthene, Pyrene and Benz(a)anthracene. This study indicates that meat singed with ST had lower PAH contents and better physical quality. The use of device and method that generates no chemical contaminants such as the ST should be encouraged for the singeing process of livestock carcasses as a strategy for the control of chemical contaminants of meat. [ABSTRACT FROM AUTHOR]

• Pyrolysis behaviors of waste tyres were studied via TG-FTIR-MS and infrared heating. • RSM was employed to optimize the pyrolysis oil yield. • The highest oil yield of 53 wt% was higher than other fixed bed reactors. • The valuable limonene has a high content of 34.03% in oil. • S combined with Zn on the char using the delocalized π electrons of aromatic rings. Developing efficient strategies to clean utilize waste tyres (WT) is essential for reducing the harm to environment. TG-FTIR-MS, infrared heating technique and response surface method (RSM) were employed to investigate the fast pyrolysis characteristics of WT in this study. Effects of temperatures and heating rates on products distribution and pyrolysis characteristics were researched in the reactor that was heated with rapid infrared heating. The TG-FTIR spectrum of volatiles indicates that there are S-O and N-H groups presented in volatiles. RSM was employed to optimize the experimental conditions to obtain a higher pyrolysis oil yield, indicating that the highest oil yield is 53 wt% at 625 °C and 25 °C/s. The pyrolysis product distribution of WT denotes that the infrared rapid heating significantly enhanced the yields of pyrolysis oil. Raising the temperature from 400 °C to 600 °C, the pyrolysis oil yield increased from 41.62 wt% to 50.66 wt%, while the temperature further rose to 700 °C, the oil yield dropped to 50.22 wt%. Meanwhile, as the heating rate elevated from 10 °C/s to 40 °C/s, the pyrolysis oil increased before decreasing and reached the maximum of 51.74 wt% at 30 °C/s. According to the GC–MS results, the primary compounds in the pyrolysis oil are aromatic and aliphatic hydrocarbons with a content of over 70 %. Moreover, N/S-containing compounds in oil retain a low yield of 6 %. The SIMDIS results prove that the light fraction of oil increased by 13.43 % and 6 % as rising pyrolysis temperature and heating rate. The results of N 2 adsorption and desorption show that the higher temperature promoted the development of the pore structure of char, while faster heating rates caused the collapse of the carbon pore structure. [ABSTRACT FROM AUTHOR]

Featured Application: This work can support the scientific community and the waste sector in the identification of the most suitable treatments for end-of-life tyres. Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Every year around 350,000 tons of end-of-life tyres (ELT) are managed in Italy, collected from cars, two-wheeled vehicles, trucks, up to large quarry vehicles and agricultural vehicles. ELTs are collected and sent for material or energy recovery, in line with the circular economy principles. This paper investigates the environmental impacts of two common scenarios of ELT treatments. Specifically, it is analysed the recycling of crumb rubber (CR, deriving from the tyre shredding) for the composition of bituminous mixtures for the wearing course of roads. This scenario is compared with the energy recovery route in a dedicated incinerator. To this aim the standardised methodology of Life Cycle Assessment (ISO 14040-44) is employed. Results shows that for most part of the impact categories analysed, the material recovery presents higher environmental benefits if compared with energy recovery. [ABSTRACT FROM AUTHOR]

The present study provides two naturally available sources for making adsorbents, waste tyres and Bauhinia purpurea leaves, for the removal of lead from effluents. Equilibrium isotherms, kinetic models and thermodynamic studies were applied to observe the suitability of these adsorbents. Response surface methodology was adopted to investigate the influence of different process variables in lead adsorption process using both the adsorbents. For all the process parameters, the square and linear model terms were having significant effect than interactive model terms of lead adsorption process for both the adsorbents. The interaction effects of the process variables of X1X2, X1X3, X2X3 and X2X4 were highly influenced by the percentage removal of lead by using activated carbons prepared from waste tyres. To study the interaction effects of the process variables of X1X2, X2X3 and X2X4 were highly influenced by the adsorption efficiency of lead by using activated carbons prepared from Bauhinia purpurea leaves. All the squared terms, X1, X2, X3 and X4 show a negative influence on the adsorption of lead on the two adsorbents. The interaction effect between process variables of X1X2 (p: 0.000, t: 9.243), X1X3 (p: 0.03, t: 2.36), X2X3 (p: 0.000, t: 4.75) and X2X4 (p: 0.02, t: 2.71), were found to be statistically significant and have positive effect on adsorption efficiency using ACWT as an adsorbent. The interaction effect between process variables of X1X2 (p: 0.000, t: 8.1049), X2X3 (t: 5.9657, p: 0.000) and X2X4 (t: 5.9657, p: 0.000) was found to be statistically significant and positive effect on adsorption efficiency of lead, whereas other interactions were insignificant and did not influence the adsorption efficiency of lead using activated carbons of Bauhinia purpurea leaves adsorbent. Based on the statistical approach, the experimental results were analysed by using ACWT and ACBPL adsorbents for the removal of lead and the optimum process conditions were as follows: pH: 4.98 and 4.77, Ci : 140.01 mg/L and 105.7 mg/L, w: 0.12 g and 0.123 g, T: 314.46 K and 305.31 K and maximum adsorption efficiency of 95.64% and 95.55%, respectively. [ABSTRACT FROM AUTHOR]

Technological processes play an essential task in the enterprise's production system. The behaviour and functioning of these systems cannot be predicted with certainty as they belong to a group of probable determinate structures. Generally, if we wanted to know precisely the behaviour of this condition in advance, we would have to be able to describe them mathematically or observe the action of the system on a real object. By applying discrete event simulation software, we realize the development of environmentally friendly products and using the simulation, we gain the certainty that the planned tasks can be implemented in a given time frame, while the simulation of the production process can help to clearly clarify and better understand the processes. To choose the optimal manufacturing ways of cleaning the fabrics component from waste tyres, we used the Witness discrete event simulation software to determine the usability and time occupancy of individual machines in the production of new fabric-based material. We simulated the ultrasonic method of cleaning the fabrics component from waste tyres and the subsequent creation of the test specimen. After the simulation, the obtained data can be used by a selection of type and number of machines and auxiliary equipment, by numbers of tools and fixtures, and by numbers of transport equipment. Obtained results bring the best layout of the workplace, the optimal dose of input materials and resources used in production. We have identified bottlenecks in the machines with long waiting times. The research priority was to reduce bottlenecks and increase the effectiveness of the entire of production line. [ABSTRACT FROM AUTHOR]

Biofuels are one of the short-term alternatives for reducing the well-to-wheel greenhouse gas footprint of transport. In the framework of compression-ignition engine fuels. This study investigates the feasibility of using cold-pressed rapeseed oil as a biocomponent, admixed with distilled tyre pyrolytic oil, as an energy-efficient alternative to commonly considered methyl ester-based mixtures in diesel fuel. Selected ternary and binary fuel blends are subjected to engine tests. Their scope covers 80% of the engine map and aims at identifying tradeoffs between fuel composition, engine performance and emissions. The results show that fuel mixtures containing a large fraction of rapeseed oil (up to 55% by volume) can be effectively combusted when pyrolytic oil distillate is introduced as the additive. The deterioration in brake efficiency for such fuel does not exceed 1.2% with respect to diesel baseline. At the same time, the results are superior in terms of both efficiency and emissions when compared to FAME-based biodiesel. Finally, with indicated efficiencies on a similar level as the diesel baseline, suggesting improved burning rate with pyrolytic oil addition, the study identifies parasitic losses in fuel injection equipment as a significant contributor to the overall efficiency penalty for the examined ternary mixtures. • Tire pyrolytic oil and its tailor-made blends with diesel and rapeseed oil examined. • Best ternary fuel samples subjected to test-bench runs on a modern CRDI engine. • Efficiency end emission factors determined and assessed w.r.t. measurement accuracy. • Slight deterioration of efficiency and emission w.r.t. diesel baseline. • Superior performance w.r.t. RME-based biofuels. [ABSTRACT FROM AUTHOR]

An innovative beam concept made from hollow FRP tube with external flanges and filled with crumbed rubber concrete was investigated with respect to bending and shear. The performance of the rubberised-concrete-filled specimens was then compared with hollow and normal-concrete-filled tubes. A comparison between flanged and non-flanged hollow and concrete-filled tubes was also implemented. Moreover, finite element simulation was conducted to predict the fundamental behaviour of the beams. The results showed that concrete filling slightly improves bending performance but significantly enhances the shear properties of the beam. Adding 25% of crumb rubber in concrete marginally affects the bending and shear performance of the beam when compared with normal-concrete-filled tubes. Moreover, the stiffness-to-FRP weight ratio of a hollow externally flanged round tube is equivalent to that of a concrete-filled non-flanged round tube. The consideration of the pair-based contact surface between an FRP tube and infill concrete in linear finite element modelling predicted the failure loads within a 15% margin of difference.

Waste tyre-derived products (TDP) are used in some engineering applications and thereby reduce the potential impact on the environment, for example, as lightweight materials in geotechnical engineering projects. One of TDPs is the baling of whole waste tyres to produce rectilinear, lightweight, permeable bales of high bale-to-bale or bale-to-soil friction. The use of lightweight tyre bales in road construction has the potential to satisfy the demand for low-cost materials exhibiting such a beneficial property. This paper presents a laboratory study on the mechanical properties of tyre bales. The laboratory tests included measurement and evaluation of full-scale tyre bales to determine basic values for the geometry and unit weight, compressibility characteristics of tyre bales, including Young’s modulus and Poisson ratio, shear strength along the tyre–tyre and tyre–soil surfaces, creep and stiffness degradation under cyclic load. The respective test procedures and results of these tests are presented in the paper. The paper provides the mechanical properties of tyre bales required for geotechnical projects, as follows: the unit weight—0.515 Mg/m3, the Young’s modulus—826 kPa, the Poison’s ratio—0.11, the dry tyre–tyre interface: cohesion of 0.03 kPa and friction angle of 46.0°, the wet tyre–soil interface: cohesion 0.77 kPa and a friction angle of 29.6°, creep deformation of 6.1% of the average height of the bale, and no stiffness degradation of tyre bales under cyclic load. These results could be directly applied for the designing and construction of the tyre-baled structures.

Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Every year around 350,000 tons of end-of-life tyres (ELT) are managed in Italy, collected from cars, two-wheeled vehicles, trucks, up to large quarry vehicles and agricultural vehicles. ELTs are collected and sent for material or energy recovery, in line with the circular economy principles. This paper investigates the environmental impacts of two common scenarios of ELT treatments. Specifically, it is analysed the recycling of crumb rubber (CR, deriving from the tyre shredding) for the composition of bituminous mixtures for the wearing course of roads. This scenario is compared with the energy recovery route in a dedicated incinerator. To this aim the standardised methodology of Life Cycle Assessment (ISO 14040-44) is employed. Results shows that for most part of the impact categories analysed, the material recovery presents higher environmental benefits if compared with energy recovery.

Foam concrete or light concrete has become increasingly recognizable in commercial and construction field. Foam concrete is not just light in its weight but also light in cost, as there is no coarse aggregate needed in its production. Application of foam concrete is limited due to the fact that it is not as strong as conventional concrete in terms of strength and rigidness. Therefore, this study is to investigate the potential of foam concrete incorporating with rubber powder of waste tire and admixture as an additive material to improve its strength and workability. Thus, the use of rubber powder in this study could enhance the strength by filling the voids in foam concrete. The amount of rubber powder added as additive in foam concrete is 0%, 5%, 10%, 15% and 20% respectively. The amount of plasticizers used is limited to less than 0.4% to the weight of cement. The mix design was set to achieve density of 1800kg/m3. The workability of foam concrete is decreasing as the percentage of rubber power was increasing. The foam concrete containing 5%of rubber powder has highest compressive strength with value of 20.6 MPa for 7 days water curing and 22.3 MPa for 28 days water curing. Significantly showing an increase of 1.7 MPa. The highest value of tensile strength for both air curing 7 and 28 days are 1.86 MPa and 1.97 MPa also held by 3% of rubber powder mix. As a conclusion the optimum rubber powder content to be used in foam concrete is 5% that gives the highest results in terms of workability and strength. [ABSTRACT FROM AUTHOR]

Highlights • The CSBR is a suitable co-pyrolysis technology as high oil yields are obtained. • Interactions among reactions lead to the formation of a stable single-phase oil. • Oil possesses improved properties, with higher carbon and lower oxygen contents. • Biomass and tires co-pyrolysis facilitates bio-oil integration in oil refineries. Abstract Pinewood sawdust and the waste rubber from truck tyres have been co-pyrolysed in order to improve the properties of bio-oil for its integration in oil refineries. In addition, an analysis has been conducted of the effect the interactions between these two materials' pyrolysis reactions have on product yields and properties. Biomass/tyre mixing ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 by weight percentage have been pyrolysed in continuous mode at 500 °C in a conical spouted bed reactor, obtaining oil yields in the 55.2–71.6 wt% range. Gaseous, oil and solid fractions have been characterised for the 50/50 biomass/tyre mixture, paying special attention to the oil fraction by determining its detailed composition, elemental analysis and calorific value. Co-processing enables the stabilization of the liquid, as the co-pyrolysis oil has a stable single phase, being composed mainly of water, aromatic hydrocarbons and phenols in concentrations of 14.5, 11.1 and 9.7 wt%, respectively. Adding tyre rubber to the biomass in the pyrolysis feed improves the oil's properties, as a liquid with higher carbon content and lower oxygen and water is obtained, even if sulphur content is also increased. [ABSTRACT FROM AUTHOR]

This review deals with the technologies of limonene production from waste tyre pyrolysis. Thermal decomposition is attractive for tackling the waste tyre disposal problem, as it enables both: energy to be recovered and limonene to be obtained. This material management recycling of tyres is environmentally more beneficial than the burning of all valuable products, including limonene. Given this recoverability of materials from waste tyres, a comprehensive evaluation was carried out to show the main effect of process conditions (heating rate, temperature, pressure, carrier gas flow rate, and type of volatile residence and process times) for different pyrolytic methods and types of apparatus on the yield of limonene. All the results cited are given in the context of the pyrolysis method and the type of reactor, as well as the experimental conditions in order to avoid contradictions between different researchers. It is shown that secondary and side reactions are very sensitive to interaction with the above-mentioned variables. The yields of all pyrolytic products are also given, as background for limonene, the main product reported in this study.

The focus on seeking alternative fuels for combustion engines has been on the environmental and political scene for many years. Simultaneously there is a more and more serious problem of non-degradable waste utilization. In the present work an attempt has been made to asses both of those aspects by proposing a tailor-made, 3-component mixture consisting of mineral diesel, crude rapeseed oil and waste tyre pyrolytic oil. It was proven that the addition of pyrolytic oil can improve some basic drawbacks of rapeseed oil / diesel mixtures like high density and viscosity or low cold filter plugging point. On the basis of maximum bio-component share and optimum physicochemical properties a best fuel sample (40% mineral diesel oil, 55% rapeseed oil and 5% pyrolytic oil fraction) had been selected for engine tests, performed on a light-duty multi-cylinder Compression Ignition (CI) engine with electronic, Common Rail (CR) injection system. The steady state tests were performed for two rotational speeds and two injection strategies (single and sequential fuel injection), for each of which a full load sweep was performed. The engine research included in-cylinder pressure analysis along with efficiency estimation and exhaust gas emission measurements. The research confirmed the assumption that the selected fuel mixture is suitable for modern CI engines. The specific fuel consumption was similar or lower for the tested fuel compared to standard diesel, except the cases were sequential injection was incorporated. Emissions remained on similar levels as for both fuels except Total HydroCarbons (THC) at sequential injection operation points, which correlated with lower fuel conversion efficiency.

In this study, two waste materials namely; coal fly ash (CFA) and waste tyres pyrolysis oil, were successfuly utilized in the synthesis of carbon nanofibers/tubes (CNF/Ts). In addition, Fe-rich CFA magnetic fraction (Mag-CFA) and ethylene gas were also used for comparison purposes. The carbons obtained from CFA were found to be anchored on the surface of the cenosphere and consisted of both CNTs and CNFs, whereas those obtained from Mag-CFA consisted of only multi-walled carbon nanotubes (MWCNTs). The study further showed that the type of carbon precursor and support material played an important role in determining the nanocarbon growth mechanism. The findings from this research have demonstrated that it is possible to utilize waste tyres pyrolysis oil vapor as a substitute for some expensive commercial carbonaceous gases. [ABSTRACT FROM AUTHOR]

In this study, we investigated the potential for use of waste tyre pyrolysis oil vapour as a carbon precursor in the synthesis of zeolite templated carbons (ZTC). With Zeolite 13X as the template, the ZTCs were synthesised using two methods namely: 1-step process which involved the carbonization of gaseous carbon precursor in the zeolite template (in this case, ethylene and pyrolysis oil vapour) and the 2-step synthesis method involved the impregnation of zeolite pores with furfural alcohol prior to carbonization of the gaseous carbon precursor. The replication of the zeolite 13X structural ordering was successful using both methods. The 2-step synthesized ZTCs were found to possess the highest specific surface area (3341 m2 g−1) and also had the highest H2 storage capacity (2.5 wt.%). The study therefore confirmed an additional novel strategy for value-addition of waste tyre pyrolysis by-products. [ABSTRACT FROM AUTHOR]

Highlights • Demineralisation in combination with pyrolysis to valorise biomass and tyre waste. • Biomass to be demineralised before pyrolysis to improve the target products. • Tyre char to be demineralised after pyrolysis to improve char value. • Water is the best solvent for weakly bonded metals: cheapest and easiest disposal. • Strong acid (or base) to remove strongly attached minerals can affect the structure. Abstract Pyrolysis is an attractive technology to convert low-cost carbonaceous waste materials into fuels, energy and other value added products goods. During pyrolysis, the inorganic minerals present in the feedstock can cause problems to the equipment and give side reactions. Besides, the minerals present in the chars can hinder their possible applications. Therefore, it seems necessary to eliminate said contaminants in order to valorise the aforementioned goods. Demineralisation is a process widely used for purifying materials that are contaminated with inorganic matter. Although this technique is commonly used with waste materials that will undergo pyrolysis, or the products obtained from it, the studies analysing this practise are rather scattered. The aim of this paper was to compile and review the current literature concerning the demineralisation of carbonaceous waste (tyres and lignocellulosic biomass) materials. The chemistry involved, feedstock type and the effect of performing the purifying step before or after pyrolysis were addressed in this work. The review revealed that biomass samples should be demineralised before pyrolysis in order to affect not only the char but also the bio-oil quality. Depending on the form in which the minerals are linked to the structure, the solvent chosen will vary (from water to strong acids). However, water is the most popular option due to its price and easy disposal. In tyres, demineralisation should be performed after pyrolysis using strong acid and subsequently base. Due to the crosslinked chemical structure, rubber is highly resistant to chemicals thus the pre-treatment has to be avoided. [ABSTRACT FROM AUTHOR]

Catalytic co-pyrolysis of grape seeds and waste tyres was performed in a fixed-bed reactor using calcined calcite as a catalyst. The organic phase obtained was analysed for its further application as a potential and stable drop-in fuel. Remarkable positive effects were achieved after the joint incorporation of both waste tyres and calcined calcite to grape seeds in the process. More specifically, the addition of considerable amounts of waste tyres (between 20 and 40 wt%) with a constant ratio of feedstock to calcined calcite of 1 were considered the optimal experimental conditions to promote positive synergistic effects on bio-oil yields and its characteristics as a fuel. Thus, when the proportion of waste tyres in the feed reached 40 wt%, the organic phase yield was considerable improved, reaching up values higher than 73 wt%, significantly greater than those obtained from conventional pyrolysis (61 wt%). Moreover, oxygen content was reduced to 4.2 wt%, minimizing any problems related to corrosivity and instability. HHV was enlarged from 15.3 up to 27.3 MJ/kg, significantly increasing the value of the resulting bio-oil. pH values and specially total acid number were also improved reaching values down to 1 mg KOH/g bio-oil in all cases. Additionally, a more valuable chemical composition was achieved since the production of aromatic and cyclic hydrocarbons was maximized, while a significant reduction in phenolic compounds was achieved. Moreover, bio-oil sulphur content was drastically reduced in comparison with the pyrolysis of waste tyres by itself from 0.6 down to 0.2 wt%. The role of calcined calcite was directly related to the promotion of dehydration reactions of acids and phenols in order to generate hydrocarbons. On the other hand, radical interactions between the biomass and waste tyres pyrolysis products played a fundamental role in the production of more valuable compounds. Finally, the CO 2 capture effect produced a more environmentally friendly gas while maintaining its calorific value. [ABSTRACT FROM AUTHOR]

Revalorisation of waste tyres to sustainable value added carbons was studied as a possible means of addressing the challenges with rising demand for energy across the globe. Crumble tyres were used for the production of activated carbon (AC) in the presence of potassium carbonate (K 2 CO 3 ) salt as the activating agent. The activated carbon (AC) materials exhibited predominantly mesoporous framework with specific surface area between 147 and 385 m 2  g −1 . Fabricated electrodes from these AC materials displayed a discharge capacity of 50 mAh g −1 at 0.25 A g −1 in a redox-mediated electrolyte of 1 M K 3 Fe(CN) 6 -1 M HNO 3 corresponding to a specific capacitance of 140 F g −1 at the same specific current, with an energy efficiency of 70% after 1000 cycles. The enhanced electrochemical performance of the electrode is due to a coupling electrolyte additive, which offers an alternative approach for the design of an efficient electrochemical energy storage device. [ABSTRACT FROM AUTHOR]

The sustainability of construction materials is a mandatory issue that started to be strongly felt in view of a global perspective of environmental protection. Wasted materials often may find a new lifecycle if well re-engineered, even in structural applications. In this field short steel fibers obtained from used tyres at the end of their life may find promising applications within a concrete matrix. In the present research the mechanical properties of recycled steel fiber-reinforced concrete in terms of workability, compressive and tensile strength, toughness and shear behaviour are analysed and compared with those of industrial steel fiber-reinforced concrete and ordinary Portland concrete. An experimental campaign is illustrated, and an extensive comparison in terms of shear strength has been studied considering different experimental works available in scientific literature. Moreover, a theoretical analysis aimed at evaluating and comparing the shear modulus of the analysed concrete type was carried out. The results obtained through this study show a satisfactory behaviour of the concrete reinforced with recycled steel fibers compared with industrial new steel fibers reinforced concrete, both in terms of toughness and shear behaviour. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC) is a highly flowable form of concrete which can be applied in complex formworks consisting of congested reinforcement without the use of any or little mechanical vibration. Over the past decades, the excessive accumulation of waste rubber tyres in Australia has led to significant research in the development of waste rubber materials to be incorporated in the concrete industry. The replacement of natural aggregates in SCC with those of rubber aggregates from waste tyre develops into what is referred to as self-compacting rubberised concrete (SCRC). This form of concrete provides a sustainable alternative which assists in minimising the environmental damages associated with the disposal of waste tyres. This project aims to develop information about the fresh and hardened properties of SCRC at incremental aggregate replacements using three different rubber aggregate sizes. The fresh properties were investigated in accordance with the guidelines provided by the European Federation National Representing of Concrete using the slump flow, T 500 , and J-ring tests. Hardened properties include 7 and 28 day compressive and tensile strengths, hardened density testing, and compressive stress-strain behaviour at 28 days. In this study optimum crumb rubber aggregates replacement percentage in SCC and optimum crumb rubber aggregates size in SCC have been presented and also optimal mix design of SCRC will be assessed to optimise fresh and hardened properties. [ABSTRACT FROM AUTHOR]