Waste Tire Research Articles

The Impact of Utilizing Waste Tire and Solid Natural Rubber as Asphalt Binder Substitutions on the Asphalt Concrete-Wearing Course Mixtures

The Impact of Utilizing Waste Tire and Solid Natural Rubber as Asphalt Binder Substitutions on the Asphalt Concrete-Wearing Course Mixtures

Highly Porous Carbon Materials Prepared Through KOH‐Assisted CO2‐Activation of Carbonized Waste Tires for Removal of Cr(VI) and Cd(II) from Water

AbstractIn this study, waste tires (WTs) were carbonized under an N2 atmosphere. Subsequently, KOH/WTs‐char with KOH‐assisted CO2 activation was used to prepare activated carbon (AC) as a highly porous carbon material for the removal of Cr(VI) and Cd(II) from water. Various techniques such as elemental analysis, Fourier‐transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption/desorption were employed to investigate the physical and chemical characteristics of the prepared carbons. The WTs‐char activated with KOH under CO2 exhibited a microstructure with a high BET surface area and pore volume of 1841 m2/g and 0.869 cm3/g, respectively, demonstrating excellent adsorbent performance. The maximum removal efficiencies of 99.91 % for Cd(II) and 99.81 % for Cr(VI) were achieved using AC2 carbon under the following conditions: pH 2 for Cr(VI) and pH 5 for Cd(II), contact time of 120 min, adsorbent dose of 0.4 g/100 mL, and temperature of 298 K. The adsorption kinetics followed the pseudo‐second‐order equation, and the equilibrium data fit well with the Redlich–Peterson isotherm equation. The positive values of ▵G indicated that the uptake process for both ions was nonspontaneous and nonfeasible over the temperature studied. Both ions showed negative values of ΔH and ΔS on carbon, suggesting exothermic adsorption and a decrease in disorder. Regeneration studies showed that NaOH was a better desorbing agent than HCl. Cr(VI) desorption resulted in over 90 % removal recovery by AC2 using 1.0 M NaOH even after the fifth cycle. However, the low activation energy indicated that the adsorption was favorable kinetically. Overall, this study demonstrated the effective preparation of highly porous carbon and its successful performance in removing Cr(VI) and Cd(II) ions.

Effect of the reclaiming degree of catalytic pre-desulfurization recycled crumb rubber on the properties of modified asphalt

The application of crumb rubber (CR) as an asphalt modifier in flexible pavements is an effective way to achieve sustainable utilisation. The performance of crumb rubber modified asphalt (CRMA) can be improved by pretreatment of CR to make it desulfurized to a certain extent. This study aims to determine the optimal regeneration degree of CR to obtain CRMA with better performance. Recycled crumb rubber (RCR) was prepared by catalytic regeneration at low temperatures and used to prepare recycled crumb rubber-modified asphalt (RCRMA). Furthermore, the characteristics of RCR with different regeneration degree and the performance of RCRMA were investigated to determine the reasonable range of regeneration degree. The results showed that solubility was a reliable indicator of the degree of regeneration of RCR and that the solubility of RCR was positively correlated with its regeneration degree. The higher the degree of RCR regeneration, the lower the molecular weight, the more uniform the distribution, and the larger the surface structure. The low-temperature performance, fatigue resistance, and construction workability of the RCRMA were better than those of the CRMA. When the solubility of RCR was greater than 30%, the compatibility and storage stability of RCRMA were significantly improved. As the solubility of RCR increases, the high-temperature performance of RCRMA decreases; however, as long as the solubility of RCR does not exceed 60%, the decrease in the high-temperature performance of RCRMA is very small. According to a comprehensive analysis, the solubility of RCR should be maintained at 30–60%.

Feasibility of utilizing recycled concrete aggregate blended with waste tire rubber and drywall waste as pavement subbase material

Feasibility of utilizing recycled concrete aggregate blended with waste tire rubber and drywall waste as pavement subbase material

Properties and stress-strain curve of rubberized concrete cast with uncoated or pre-coated rubber with cement/waste materials

Replacement of fine aggregate with crumb rubber (CR) in concrete manufacturing has become necessary to reduce environmental problems resulting from the traditional disposal of waste tires and to produce environment-friendly concrete. The main problem resulting from incorporating CR into the concrete industry remains the reduction in the properties of concrete. Various methods have been employed to treat CR particles to enhance the overall performance of crumb rubber concrete (CRC). Nevertheless, most of the suggested treatment techniques exhibited little efficacy in improving the characteristics of CR particles, and certain chemical treatments pose risks and hazards to the environment. This work presents a novel method for pre-treating CR particles before their use in CRC. The methodology involves the utilization of several processing materials, including cement (C), supplemental cementitious materials (SCM) such as fly ash (FA), and waste materials such as marble powder (MP). Seventeen different mixtures in terms of rubber replacement ratios and rubber processing methods were prepared for the experiment. One mix served as the control without any addition of CR. Four mixtures were generated by substituting varying proportions (5%, 10%, 15%, and 20%) of sand with untreated CR, measured by weight. The remaining twelve mixes contain treated CR with C, FA, and MP. This study investigated the fresh and mechanical properties of CRC, as well as the overall behavior of the stress-strain curve, including yield, peak, ultimate strain, toughness, modulus of elasticity, and strain ductility. The findings indicated that pretreatment of CR with one of the proposed materials enhances the overall behavior of CRC, especially using FA, compared to untreated. The substitution of fine aggregate with 20% CR treated with FA significantly improved the overall properties of CRC. The compressive strength, splitting tensile strength, peak stress, modulus of elasticity, and toughness rose by 22%, 21.30%, 31.19%, 5.30%, and 37%, respectively, compared to using the same proportion of untreated rubber. Therefore, this type of treatment can be relied upon to improve the properties of CRC and give acceptable results.

Recycling of Industrial Waste as Soil Binding Additives-Effects on Soil Mechanical and Hydraulic Properties during Its Stabilisation before Road Construction.

To improve the in situ soil stabilization, different chemical additives are used (ion exchange compounds, additives based on H2SO4 or vinyl polymers, and organic additives using lignosulfonates). One interesting alternative is the production of additives from various waste materials. The extensive testing of waste-based blends with soil was performed; the mechanical (unconfined compressive strength (UCS)) and hydraulic (capillary rise, water absorption, and frost resistance (FR)) soil properties were measured. The optimization process led to obtaining additive compositions ensuring high strength and sealing properties: by-pass ash from the ceramics industry, waste H2SO4, pyrolytic waxes/oils from waste mixed plastics, waste tires and HDPE, and emulsion from chewing gum waste. For sandy soil, the following additives were the most promising: emulsion from pyrolytic wax (EPW) from waste PE foil (WPEF) with the addition of waste H2SO4, pyrolytic-oil emulsion from waste tires, EPW from waste mixed plastics with the addition of "by-pass" waste ash and NaOH, EPW from WPEF with the addition of NaOH, and EPW from WPEF reaching up to 93% FR, a 79.6% 7-day UCS increase, and a 27.6% of 28-day UCS increase. For clay: EPW from WPEF with the addition of NaOH, EPW from WPEF with the addition of waste H2SO4, and solely EPW from WPEF reaching up to 7.5% FR, an 80.7% 7-day UCS increase, and a 119.1% 28-day UCS increase.

Energy recovery from sewage sludge waste blends: Detailed characteristics of pyrolytic oil and gas

Using waste as an alternative energy source may partially replace fossil fuels. In this paper, energy recovery from waste blends (sewage sludge (SS), polyethylene (LDPE) and polypropylene (PP), paper rejects (PR), and waste tyres) was tested through laboratory-scale co-pyrolysis. For each co-pyrolysis test, 7 l of waste blend in different ratios were used. The results of pyrolytic oil and gas analyses show valuable compounds and chemical materials recovered. The detailed analyses show the effects of co-pyrolysis parameters, especially the ratios of waste blends with respect to the process temperature of 600°C, on the pyrolytic gas and oil. The highest volumes of gas (0.66 m3) and oil (699 ml) were obtained from sample 5_8 (PES:SS:PR). Waste blend 15_1 (LDPE:SS) had the highest gross calorific value (GCV) of 43.82 MJ/m3 in gas, and had the highest proportion of flammable components (46.31% of methane). Sample 5_8 had the highest calorific value in pyrolytic oil (45 MJ/kg) and sample 5_3 had the lowest (28.113 MJ/kg), which is comparable to coal. High-quality pyrolytic gas and oil were obtained with average GCV of 44 MJ/m3 and 40 MJ/kg respectively, where the average GCV of the most calorific fossil fuels is 43.6 MJ/kg in crude oil and 34 MJ/m3 in natural gas. We conclude that co-pyrolysis of sewage sludge and waste is a convenient and simple method of waste disposal under a synergetic effect of efficient waste management, energy production, and reduction of dependence on fossil fuels.

Influence of Slag, Silica Fume and Waste Tire Wire on High-Strength Characteristics of Geopolymer Concrete Cured Under Ambient and Oven Conditions

Influence of Slag, Silica Fume and Waste Tire Wire on High-Strength Characteristics of Geopolymer Concrete Cured Under Ambient and Oven Conditions

Enhancing the Strength and the Environmental Performance of Concrete with Pre-Treated Crumb Rubber and Micro-Silica

Dumped non-biodegradable tires present a significant environmental threat, with overflowing landfills and associated health risks highlighting the urgency of tire waste disposal. Current disposal methods, such as stacking tires in open spaces, exacerbate the problem. The large-scale recycling of tire rubber waste offers environmental benefits. This study examines the effects of pre-treatment using NaOH and micro-silica as a mineral admixture on the mechanical strength of crumb rubber concrete (CRC) with partial replacement of natural sand. Samples of M20 and M30 grade were prepared with varying levels of crumb rubber (CR) replacement and evaluated at 28 days. CRC prepared with pre-treated NaOH solution and micro-silica showed improved workability and strength compared to conventional concrete and untreated CRC, with the highest strength observed for 5% CR replacement using micro-silica. Predictive models and micro-structural analysis validated these findings. Life Cycle Assessment (LCA) using OpenLCA v2.10 software and the ecoinvent database revealed that incorporating micro-silica into CRC did not significantly increase environmental impacts, compared to conventional concrete across different mixes.

Flexural Response of Functionally Graded Rubberized Concrete Beams.

Recycling rubber and/or steel fiber components of waste tires in construction applications is a venue for maximizing the recycling rate of these items. Additionally, it supports the move towards producing sustainable construction materials and conserving natural resources. Previous research explored the viability of employing recycled waste rubber particles as an alternative for natural aggregate. Despite the adverse effect of rubber on the mechanical properties of concrete (e.g., lower compressive strength), it produces several advantages, including excellent dynamic and ductility properties, which can be utilized in structural members critical to dynamic loads, e.g., blasts, earthquakes, and impacts. In an effort to expand the adoption of waste rubber in concrete beams and to eliminate key concerns associated with the degradation of their flexural behavior, the functionally graded (FG) beams concept was utilized. The present investigation comprised the testing of five beams using a four-point bending configuration. Plain concrete, rubberized concrete (RuC), and steel-fiber reinforced rubberized concrete (SFRRuC) beams were cast along with FG beams arranged in two layers. The top layer of the FG beams comprised plain concrete, while the bottom layer consisted of RuC or SFRRuC. Experimental findings indicated that the flexural behavior of the FG beam with layers of SFRRuC and plain concrete exceeded the flexural strength, displacement ductility ratio, and toughness performances of the plain concrete beam by 9.9%, 12.9%, and 24.4%, respectively. The moment-curvature relationship was also predicted for the tested beam and showed an excellent match with the experimentally measured relationship.

In situ self-activation strategy for the synthesis of double-layered S/Cl co-doped sorbents for elemental mercury removal from oxy-fuel combustion flue gas

Mercury capture from oxy-fuel combustion flue gas remains an enormous challenge for carbon capture and storage because of the lack of cost-effective, sulfur-resistant and water-resistant sorbent. In this work, double-layered S/Cl co-doped sorbents (CDSs) were synthesized through an in situ self-activation method i.e. co-pyrolysis of waste tire and PVC plastic, which were adopted for elemental mercury (Hg0) immobilization from oxy-fuel combustion flue gas. A synergistic effect between waste tire and PVC plastic was observed during co-pyrolysis. For this reason, chlorine was successfully doped into the CDSs in the form of covalent chlorine and ionic chlorine. The CDSs showed high Hg0 removal efficiency (>80 %) over a wide temperature range (20–140 °C) and excellent sulfur and water resistance. Both the initial Hg0 adsorption rate and adsorption capacity of CDSs were far higher compared with raw tire char. The Hg0 removal mechanisms were further proposed, where Hg0 preferentially reacted with covalent chlorine instead of active sulfur species. Density functional theory calculations revealed that the Hg0 adsorption over CDSs was chemisorption with an adsorption energy of −249.85 kJ/mol. The synergistic effect between sulfur and chlorine was beneficial for the formation of HgCl2 whereas it had negligible effect on the formation of HgCl.

Sustainable solutions for railway using recycled rubber

This paper introduces four innovative applications of waste rubber from scrapped tyres or conveyor belts in railway tracks. They include (a) a synthetic energy-absorbing layer of coalwash, steel furnace slag and rubber crumbs (SFS + CW + RC) for railway subballast, (b) a rubber inter-mixed ballast system (RIBS), (c) energy-absorbing rubber geogrids, and (d) a hybrid track incorporating tyre cells and elements of off-the-road truck tyres. Comprehensive laboratory and field tests have been conducted to investigate the geotechnical properties of these applications. Specifically, an empirical model was developed to predict the permanent deformation response of SFS + CW + RC mixtures that incorporate the effect of granular rubber and axial loads based on cyclic triaxial tests. Large-scale triaxial tests and field trials proved that RIBS exhibited improved energy-absorbing properties, sufficient shear strength and the promising ability to mitigate ballast breakage and stress distribution. A rubber geogrid with an optimal rib thickness of 10.6 mm was selected based on drop-hammer impact tests. The performance of the hybrid track was investigated using the National Testing Facility for High-speed Rail (NTFHR), from which it was found that the reinforced track had significantly less settlement, lateral deformation and ballast breakage than the traditional track.

A comparative study of aromatic content in pyrolysis oils from waste plastics and tires: Assessing common refinery methods

The conversion of waste plastics and tires via pyrolysis to pyrolysis oil represents one of the most promising ways of chemical recycling. Determining aromatics in pyrolysis oils from these feedstocks is crucial for their utilization as both petrochemicals and fuels. In this study, we compared three standard methods commonly available in refinery laboratories (ASTM D1319 − FIA, EN12916 − HPLC-RI, ASTM D8396 − GC × GC-FID) for analyzing aromatic content across a wide range of waste plastic pyrolysis oils, their middle distillate fractions, and hydrotreated products. Using model compounds, we explained most of the observed differences in aromatic content determined by these methods. HPLC-RI and FIA resulted in significant errors. For instance, the FIA reports some dienes and heterocompounds as aromatics. The results from HPLC-RI showed that monoaromatics are overestimated, while polyaromatics are underestimated. Among the tested methods, GC × GC-FID provided the most reliable results.

THE EFFECT OF ADDING WASTE TIRE RUBBER POWDER ON PAVING BLOCK WEAR

Pavement using paving blocks is the right choice because of its easy installation and maintenance. One form is a quadrilateral type that is widely used for environmental and pedestrian roads. With good road access being one of the improvements in vehicles so that waste tires also increase, solutions are needed to reduce the impact on the environment but are also expected to provide benefits for paving block roads, especially increasing adhesion between paving block constituent materials. Based on this background, it was a research idea with the aim of determining the effect of adding waste tire rubber powder on the wear resistance of paving blocks. Research method with strength testing on paving block samples with a size of 5 cm x 5 cm x 2 cm a total of 18 samples. The results showed the average strength value of paving blocks with a mixture of waste tire rubber of 1%, 2%, 3%, 4%, 5% of 0.134, 0.223.0235, 0.246 and 0.247 mm / minute, so that the addition of waste tire rubber powder showed a decrease in the wear rate of paving blocks.

Experimental Study on the Cyclic Performance of Novel Seismic Base Isolators Made by Scrap Tire Rubber Pads

Experimental Study on the Cyclic Performance of Novel Seismic Base Isolators Made by Scrap Tire Rubber Pads

Utilization of waste rubber tyre in soil stabilization

This paper explores the feasibility and benefits of utilizing waste rubber tyre for soil stabilization purpose.With the growing environmental concern surrounding waste tyre disposal, repurposing them for soil stabilization presents a sustainable solution. Added amount of rubber tyre had been varied in proportions of 10%, 15%, 20% and 25%.Waste rubber tyre helps in improving the desired properties of soil and minimizes the amount of waste to be deposited in environment causing environmental pollution. Rubber tyres are cost effective and is quite easily available, due to day by day increase in cost of stabilizers like cement, lime and other admixtures;use of shredded rubber tyre can result in project completion optimally. The soil sample used is clay, thus being highly plastic it is required to be strengthened by using varying proportion of shredded rubber tyre. The effect of shredded rubber tyre on soil is analysed by conducting various tests that governs the basic properties of soil and the obtained result shows that increasing the percentage of shredded rubber tyre results in enhancement in desired soil properties.Increase specific gravity, increase liquid limit, and decrease plastic limit are achieved through the incorporation of appropriate additives in soil stabilization processes. Key Word: Waste rubber tyre, Soil stabilization, Tyre recycling, shredded rubber tyre, Engineering properties, clay soil.

Assessment of mechanical behavior of sprayed concrete reinforced with waste tire textile fibers

The primary objective of this research is to assess the mechanical properties of shotcrete or sprayed concrete reinforced with waste tire textile fibers (WTTFs). Shotcrete is extensively employed in civil and mining engineering projects for support systems. This study examines the physical and mechanical characteristics of shotcrete samples, both without fibers and reinforced with WTTFs, including density, water absorption, volume of permeable voids, ultrasonic pulse velocity, uniaxial compressive strength, and splitting tensile strength. The reinforced samples consist of WTTF fibers at 0.5%, 1%, and 1.5% concentrations. Test results demonstrate that the inclusion of waste tire textile fibers enhances the mechanical properties of shotcrete, particularly its deformability and energy absorption capacity. Based on the test outcomes, a 1% fiber concentration is recommended as the most suitable ratio for utilizing waste tire textile fibers in shotcrete. Furthermore, these flexible fibers do not impede shotcrete pumping or spraying capabilities.

Co-pyrolysis of waste tire with agricultural and forestry residues: Pyrolysis behavior, products distribution and synergistic effects

Co-utilization of waste tires (WT) and agricultural and forestry residues (AFR) provides an effective means to produce energy while simultaneously providing solution for waste treatment and environment protection. In this paper, co-pyrolysis of WT and AFR (cotton stalk, CS, peanut shell, PS, and poplar branch, PB) was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectrometer (FTIR), and pyrolyzer coupled with gas chromatograph/mass spectrometer (Py-GC/MS). The synergistic effects of mass loss rate and hydrocarbon content were quantified from the results of co-pyrolysis of WT with CS, PS, or PB with the weighted average of individual pyrolysis of the feedstocks. The results showed that the mass loss rate of WT with CS, PS, or PB in co-pyrolysis increased by 3.06 %, 3.84 %, and 0.61 %, respectively, compared to the weighted average of individual pyrolysis, while the hydrocarbon content increased by 19.20 %, 18.26 % and 2.97 %, respectively. The addition of AFR to WT made the pyrolysis easier. In co-pyrolysis, the amount of O-compounds decreased while that of hydrocarbons (aromatic hydrocarbons and aliphatic hydrocarbons) increased. Co-pyrolysis of AFR and WT had an effect on reducing aromatic and nitrogen content. These results provide insights into the synergistic effects, from the products distribution and offer potential waste treatment method for these wastes via thermochemical conversion.

Electrochemical performance of chemically treated pyrolytic carbon black from waste car tyres

Pyrolytic carbon black (CBp) is a solid by-product of tyre pyrolysis that contains various contaminants from the tyre additives. These contaminants limit the use of CBp as a carbon source for energy storage applications such as supercapacitors. This study aims to improve the physicochemical, morphological, and electrochemical properties of CBp by applying different chemical treatments and activation methods. The chemical treatments include acid (HCl), base (NaOH), acid-base (HCl/NaOH), and desulphurization (NaOH in xylene) processes to remove impurities such as sulphur, zinc, and silicon. The treated CBp samples are then activated by KOH impregnation technique to increase the surface area and porosity. The characterizations of the treated CBp samples are performed using Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), and Brunner Emmett Teller (BET). The electrochemical performance of the treated CBp samples are evaluated using galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that the chemical treatments significantly reduce the impurity levels and enhance the electrochemical performance of CBp. The desulphurized CBp sample exhibits the highest specific capacitance of 218 F/g among the treated CBp samples. The findings of this study suggest that CBp can be effectively utilized as a potential carbon source for supercapacitor electrodes by applying suitable chemical treatments and activation methods. This will create a circular economy to valorize CBp.

Physical and Chemical Methods to Assess Performance of TPO-Modified Asphalt Binder

The demand for effective asphalt additives is growing as road infrastructure ages and more sustainable pavement solutions are needed. Tire pyrolysis oil (TPO) is an example material that has been gaining attention as a potential asphalt additive. While physical performance grade (PG) temperatures are the predominant performance requirements for asphalt binders, chemical properties are also significant in the evaluation of asphalt performance. There is a need to chemically characterize the aging of asphalt binders modified with TPO and link chemical changes in binder components to binder performance. This study compares 2%, 4%, and 8% TPO and asphalt binder blends via dynamic shear rheometry (DSR), Fourier-transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) relaxometry. The variability in the modified blends was seen by both physical and chemical testing during four different blending times (1, 60, 120, and 240 min). After blending, high and intermediate PGs were determined by physical testing. The 8% TPO blend reduced the high PG of the binder from 64 °C to 58 °C. This effect was confirmed by chemical testing through changes in carbonyl indices and NMR relaxation times. With more oil present in the binder matrix, the binder’s resistance to rutting was reduced. While the high PG was hindered, the intermediate PG remained unchanged for all TPO blends. This physical similarity was mirrored in chemical testing. The chemical and physical variability along with the hindrance of the high PG temperature indicate that more treatment may be needed before TPO can be effectively applied to asphalt binders. This study suggests a correlation between physical performance and key chemical indicators.