Recycling Waste Tire Rubber Research Articles

Characterization of wood plastic composites made with recycled waste tire rubber

Abstract Green materials are currently demanded for construction as well as other products since the 26th UN Climate Change Conference of the Parties (COP26) in 2021. Using renewable and sustainable resources to innovate new materials such as composites is encouraged. This study aimed to investigate the physical and mechanical characteristics of wood plastic composites (WPCs) when adding waste tire rubber as filler for 10% or 20% by weight. The results showed that the density of the WPC samples (50 wt% wood − 50 wt% high density polyethylene) increased with the addition of the waste tire rubber (WTR) while the dimensional stability of samples was reduced. The mechanical properties of the WPC samples were determined, including flexural strength, flexural modulus, elongation at break, tensile strength, tensile modulus, and impact strength. The WTR as filler in the WPC tended to decrease the tensile strength and flexural strength whereas it improved the impact strength of materials. The results indicated that the WTR as recycled material in WPC affected the physical and mechanical properties of the WPCs. Although the use of the WTR in the production of the WPC adversely affects the mechanical properties, the use of 10 wt% WTR was acceptable. The results of the study showed that the addition of the WTR to the WPC production process can be useful for its recycling and for reducing the cost of the WPC.

Numerical simulation of the deformation behavior of a composite foundation consisting of rubber particle loess-CFG under dynamic loading

The CFG pile technology is primarily employed for foundation reinforcement, offering cost-saving benefits and demonstrating significant reinforcement effects. Consequently, it has gained widespread utilization. However, due to its unique composition and exceptional strength characteristics, investigating the dynamic properties of rubber particle loess-CFG poses significant challenges. In this study, a numerical simulation approach is employed to investigate the dynamic characteristics of rubber particle loess-CFG and its deformation response under dynamic loading is analyzed. The results indicate that the deformation of rubber particle loess-CFG remains minimal under static loading, while it significantly increases under dynamic loading. However, the vertical and horizontal displacements at the top of the mattress layer are comparatively smaller than those observed in loess-CFG, highlighting their seismic stability. The mattress layer of the rubber particle loess-CFG undergoes vertical compression and deformation, while being horizontally squeezed towards the central region. The horizontal displacement and its variation range are significantly greater than that of the entire pile and the soil between piles. Therefore, it is crucial to analyze the material properties, thickness, and extent of the mattress layer during design in order to mitigate its influence. When subjected to dynamic loading at the base of the model, the rubber particle loess-CFG exhibits a strip distribution of vertical displacement which gradually decreases from bottom to top. Moreover, as focal depth increases, the impact of dynamic loading on foundation deformation diminishes. Consequently, rubber particle loess-CFG provides a dual functionality of enhancing foundation strength while effectively resisting dynamic deformations. These research findings provide a theoretical basis for designing reinforced foundations using rubber particle loess-CFG and offer an innovative approach for recycling waste tire rubber particles.

Sustainable 3D printing with recycled tire rubber-based filaments: an investigation of process parameters and mechanical behaviour

PurposeThis study evaluates the potential of using the material extrusion (MEX) process for recycling waste tire rubber (WTR). By investigating the process parameters, mechanical behaviour and morphological characterisation of a thermoplastic polyurethane-waste tire rubber composite filament (TPU-WTR), this study aims to establish a framework for end-of-life tire (ELT) recycling using the MEX technology.Design/methodology/approachThe research assesses the impact of various process parameters on the mechanical properties of the TPU-WTR filament. Hysteresis analysis and Poisson’s ratio estimation are conducted to investigate the material’s behaviour. In addition, the compressive performance of diverse TPU-WTR triply periodic minimal surface lattices is explored to test the filament suitability for printing intricate structures.FindingsResults demonstrate the potential of the TPU-WTR filament in developing sustainable structures. The MEX process can, therefore, contribute to the recycling of WTR. Mechanical testing has provided insights into the influence of process parameters on the material behaviour, while investigating various lattice structures has challenged the material’s capabilities in printing complex topologies.Social implicationsThis research holds significant social implications addressing the growing environmental sustainability and waste management concerns. Developing 3D-printed sustainable structures using recycled materials reduces resource consumption and promotes responsible production practices for a more environmentally conscious society.Originality/valueThis study contributes to the field by showcasing the use of MEX technology for ELT recycling, particularly focusing on the TPU-WTR filament, presenting a novel approach to sustainable consumption and production aligned with the United Nations Sustainable Development Goal 12.

Physico-Mechanical Characterization of Recycled Waste Tire Rubber and Rice Straw Reinforced Composite

Physico-Mechanical Characterization of Recycled Waste Tire Rubber and Rice Straw Reinforced Composite

Recycling waste tire rubber through an innovative water-medium ionizing radiation treatment: Enhancing compatibility and mechanical performance

In this research, we solved the compatibility problems of rubber mixtures containing waste ground tire rubber (GTR) with an innovative and environmentally friendly, water-based ionizing radiation treatment, meaning that the GTR is under water. Our hypothesis was that the strong oxidizing agents that appear during the radiolysis of water can activate the surface of the GTR, resulting in reactive functional groups containing oxygen, which can help establish a better interaction between the matrix and the GTR. We treated the GTR using different absorbed doses and examined the changes in the GTR using Soxhlet-extraction and cross-link density measurements. The surface of GTR was characterized by Fourier-transform infrared spectroscopy. Then we prepared GTR-containing natural rubber-based mixtures in an internal mixer, using two different mixing techniques. The mixtures were vulcanized in a hydraulic press, and the mechanical and morphological properties were investigated. As a result of the radiation treatment, cross-link density decreased slightly, while sol content did not change significantly. The FTIR spectra indicated that oxygen-containing groups appeared on the surface of the treated GTR. In the case of one-step vulcanizates, tensile strength increased by 11% and tear strength by 40%, while elongation at break remained high. For the two-step mixtures, tensile strength improved by 25%, tear strength by 35%, while elongation at break was over 400%. An irradiation dose of 20 kGy produced the best result, which is sustainable in mass production.

Experimental Static and Dynamic Characteristics of Recycled Waste Tire Rubber Particle-Cement-Sand Composite Soil.

To investigate the static and dynamic characteristics of rubber-sand composite soil (RS soil) reinforced with cement, a series of triaxial compression tests and resonant column tests was performed by considering the influence of rubber content (10%, 20%, 30%, 40%, and 50%), cement content (0, 1.5, 2.5, 3.5 and 4.0 g/100 mL), and effective consolidation confining pressure (50, 100, and 150 kPa). Compared with the RS soil, the addition of cement significantly improved the shear strength of a cement-rubber-sand composite soil (RCS soil), based on an undrained shear test. The increase in cement content not only makes the elastic modulus and cohesion of the RCS soil increase but also reduces the internal friction angle of the RCS soil. With the increase in rubber content, the failure of the RCS soil samples changes from strain-softening to hardening, and the prediction equation of the initial elastic modulus of the RCS soil is given herein when the recommended cement content is 3.5 g/100 mL. The effects of rubber content, cement content, and effective confining pressure on the dynamic shear modulus and damping ratio of the RCS soil were studied via the resonant column test. The test results show that the increase in rubber content slows down the modulus attenuation of the RCS soil, but increases its damping ratio. The test results also show that the increase in cement content makes the bonding force between particles greater so that the modulus attenuation of the RCS soil becomes slower and the damping ratio is reduced. At the same time, according to the change rule of the maximum dynamic shear modulus of the RCS soil with the rubber content, when the recommended cement content is 3.5 g/100 mL, an empirical formula and recommended value of the shear modulus Gmax of the RCS soil are proposed.

Atık Lastik Kauçuk Granül/Polyester Polimer Matris Kompozitinin Çekme ve Morfolojik Özellikleri

In this study, waste tire rubber granules were used as filler material for the fabrication of polymer matrix composite samples. The polyester resin which is one of the most preferred matrix materials and recycled waste tire rubber granules were combined at varying ratios with the open molding method. The samples were characterized experimentally by conducting tensile and hardness tests. The morphological properties of the specimens were examined with scanning electron microscope images. The study revealed that the addition of untreated waste tire rubber granules to polyester resin decreases the tensile and yield strength values, while it causes to increase in elongation and ductility of the material. The morphological examinations showed that waste rubber granules and polyester resin have poor interfacial adhesion and thus the waste rubber granules should be properly treated to be used as filler material. The study indicated that waste tire rubber granule/polyester composites can be used for non-structural applications with the benefits of using less fossil sourced raw materials and contributing to the decrement of environmental pollution.

Sustainable Asphalt Rejuvenation by Using Waste Tire Rubber Mixed with Waste Oils

Waste materials such as waste tire rubber (WTR), waste cooking oil (WCO), bio-oils, waste engine oil (WEO), and other waste oils have been the subject of various scientific studies in the sustainable and waste research field. The current environmental concerns have been identified to protect natural resources and reuse waste materials. Accordingly, this work reviews the use of recycled waste tire rubber mixed with waste oils (waste cooking oil, waste engine oil) and bio-oils that can be extracted from waste oils to rejuvenate asphalt in reclaimed pavements. This new solution may reduce the massive amounts of WTR and waste oils and produce a more environmentally sustainable material. Reclaimed, aged asphalt has been rejuvenated to achieve various penetration capabilities and properties by blending asphalt with one or more waste materials to evaluate the binder using standard tests. Many solutions with promising results in improving the properties of asphalt mixtures have been selected for further characterization. This review highlights that the addition of WTR and waste materials to rejuvenated asphalt binders improves stability, enhances the viscoelastic properties, provides better fatigue and crack resistance performance, and enhances the compatibility of the rejuvenated rubber oil asphalt. Moreover, the flashing point, softening point, ductility, and penetration of aged asphalt and Poly(styrene-butadiene-styrene)-rubber-rejuvenated and waste-rubber-oil-rejuvenated asphalt were enhanced after applying the rejuvenator compound. On the other hand, adding waste oil to WTR and asphalt reduces the viscosity and enhances the storage stability compared to the asphalt rubber binder.

Subject Review: A Comparison of Using Recycled Rubber as Aggregate in Concrete

Due to the growth of the population, waste tires have a significant effect on the environmental issue. Every year, the decomposition of waste tire rubber is rapidly rising. Also, recycle rubber scraps into concrete production the main issue could be decreased. Recycle rubber scraps could be combined in concrete by substituting with fine and/or coarse aggregate. Decreasing the fine and coarse aggregate and preserving these natural materials. Furthermore, recycling the rubber scraps avoids the need for tire landfilling, as one of the main environmental problems of the future. A lot of investigation has suggested the use of alternative materials in concrete production, one such material that has gained a lot of attention is the recycled waste tire rubber. This study investigates of existing efforts of the literature studying recycled rubber scraps used as sand and gravel substituting in concrete production and its effect on numerous concrete characteristics.

Decision support for selecting optimal method of recycling waste tire rubber into wax-based warm mix asphalt based on fuzzy comprehensive evaluation

Recycling crumb rubber (CR) derived from waste vehicle tire as asphalt modifier is an effective waste management approach with both engineering and environmental merits. However, the high viscous asphalt rubber (AR) brings higher energy consumption and hazardous construction emission. Wax-based warm mix asphalt (WMA) additive has proven to be able to alleviate these concerns. Application of WMA additives enriches the methods of recycling CR into asphalt. Preliminary investigations documented the effects of CR recycling methods on the service performance of warm crumb rubber modified asphalt mixture (WCRMA). Therefore, making a decision on the optimal recycling method considering the overall service performance is necessary. Nevertheless, there are limited studies focusing on the recycling method assessment and decision-making approach. To fill this gap, WCRMAs with different crumb rubber recycling methods were prepared and tested in laboratory. The effect of the recycling method on the overall service performance of WCRMAs was characterized. A fuzzy comprehensive evaluation (FCE) method was employed to quantify the performance grade of asphalt mixtures according to fuzzy logic. The weight matrix of all the service properties was developed based on the Analytic Hierarchy Process (AHP) under the considering of the circumstance of southern China. The experimental work revealed the significant influence of the recycling method on the service performance of WCRMAs. By means of the FCE method, this study suggested that for southern China with hot and humid climate, the optimal method of recycling CR into wax-based WCRMA is mixing AR and Sasobit first followed by incorporating them into aggregate. In rainy regions, asphalt mixture produced by directly mixing AR, Sasobit, and aggregate at 160 °C may perform better because it showed the best moisture damage resistance and good overall performance.

Recycled tires shreds based polyurethane binder: Production and characterization

End-of-life tires are known to have negative economic and environmental impacts due to their difficult disposal and recycling. Thus, the use of recycled waste tire rubber particles mixed with an elastomeric polyurethane resin dyed in the mass has emerged as a potentially sustainable solution to this environmental issue. Indeed, they can be used for the manufacture of damping tiles for playgrounds and sports fields, which limit the risks associated with falling. This is a product that interests town halls, businesses and individuals. In this study, the recycled waste tire rubber particles and their fibers byproducts are introduced into a new binder based on commercial polyurethane adhesive (Vinyprene P2006) blended with a polyisocyanate hardener to elaborate a low-cost composite. Also, halogenation is proposed as a surface modification to improve the interfacial adhesion between the binder and the particles. The samples were produced with two densities and characterized using SEM and FTIR, as well as bonding, compression, relaxation and residual deformation. The results show that the chemical treatment increased the rubber surface roughness which improved the binder ability, and on the other hand, the rubber composites exhibit higher compression properties than the rubber mixed the fiber by product composites.

Evaluation of microcracks in the interfacial transition zone of recycled rubber concrete

AbstractThis work focuses on the feasibility of recycling waste tire rubber aggregates into recycled concrete. The performance of interface transition zone (ITZ) is a key factor affecting the mechanical properties and durability of concrete. The influence of rubber particle size (5–10, 10–20, 20–50, and 50–90 mesh) and volume fraction of rubber aggregate (0, 10, and 20%) on the ITZ of common and rubber aggregate‐cement pastes was studied. Scanning electron microscopy was used to observe the microstructure of recycled rubber concrete cured at constant temperature and humidity for 28 days. Moreover, the size of microcracks in the ITZ area was evaluated. Results showed that the crack width of the ITZ between the rubber and cement paste (ITZ‐R) and between the ordinary aggregate and cement paste (ITZ‐S) showed similar variation patterns. The addition of 50–90 mesh rubber powder improved the ITZ micro‐crack structure of rubber concrete. Increasing the rubber content and particle size also increased the microcrack width of ITZ. The size of rubber aggregate was the key factor affecting the crack width in ITZ. Finally, the addition of rubber inhibited the hydration degree of cement, reduced the formation of hydration products in ITZ and substantially affected ITZ‐R.

A review on devulcanization of waste tire rubber

Rubber has become an indispensable material for the technological development of civilization, including simple balloon and complex rocket propellant. Rubber Industry worldwide is using on an average 50% of raw materials. These materials were mostly petroleum-based, except natural rubber (NR), steel cord and bead wire. Using of these petroleum-based raw materials not only depletes natural resources, but also produces more extreme environmental hazards. The waste tire rubber problem is of great magnitude and has far reaching environmental and economic implications. There are some ways for recycling of rubber, such as reclaiming technology, surface treatment, grinding and pulverization technology, devulcanization technology. Methods of devulcanizing rubber (or elastomers) have been researched almost since the time of the discovery of the rubber/sulfur vulcanization process. By devulcanization process the cross-links in the structure of rubber are broken and devulcanized rubber can be revulcanized into a raw material for rubber industry, which is a highly valued form of waste rubber. This study provides a review of the recent advances in understanding of methods of recycling rubber and claims that the capacity of thermomechanical and mechanochemical devulcanization methods of recycling waste tire rubber can be improved in future studies.

Recycled Rubber as an Aggregate Replacement in Self-Compacting Concrete-Literature Overview.

In the past few decades, due to the exponential increase of the world’s population, the number of discarded waste tires has become a serious ecological and environmental problem. Decomposition of waste tire rubber can take longer than 50 years, and every year the number of discarded tires is rapidly growing. With the inclusion of waste tire rubber into self-compacting concrete this global problem can be reduced. Waste tire rubber can be incorporated in self-compacting concrete by partially replacing the natural fine and coarse aggregate, reducing consumption of sand and gravel and preserving these natural materials. In addition, recycling and reusing waste tire rubber avoids the need for tire landfilling, as one of the major ecological problem of the near future. Replacement of natural aggregate with waste tire rubber can have an undesirable influence on the mechanical properties of self-compacting concrete, i.e., compressive strength, flexural strength, splitting tensile strength, and modulus of elasticity, however. On the other hand, replacing natural gravel or sand with waste tire rubber can improve impact resistance, ductility, and fatigue resistance. This paper presents an overview of the literature investigating recycled waste tire rubber used as a fine and/or coarse aggregate replacement in self-compacting concrete and its influence on several essential fresh and hardened self-compacting concrete properties.

Modified Pervious Concrete Containing Recycled Asphalt Pavement and Waste Tire Rubber

Portland Cement Pervious Concrete (PCPC) can reduce the risk of flash flood by letting the storm runoff to sip through the voids available in the PCPC hence infiltrate into the soil. This unique ability of pervious concrete offers advantages to the environment, public agencies, and building owners by controlling rainwater on site and addressing storm water runoff issues. Thus, this study was conducted to substantiate the usage of inorganic, cheap and reusable material namely Recycled or reclaimed asphalt pavement (RAP) and Fine Crumb Rubber (FCR) in pervious concrete. The primary objective of this study is to compare the compressive strength, density and the surface infiltration rate of pervious concrete containing waste tire rubber with pervious concrete that is made up by using natural aggregate without any enhancement. Standard pervious concrete will consist of natural coarse aggregates and cement. In this study, RAP will be replacing the natural coarse aggregates, the same size with the previous research. The modified pervious concrete will also be mixed with a certain percentage of FCR, replacing certain percentage of the coarse aggregate. The results of this study indicate that using recycled material could achieve similar performance as using natural aggregate, hence may reduce the construction cost.

Laboratory Investigation on the Effects of Natural Fine Aggregates and Recycled Waste Tire Rubber in Pervious Concrete to Develop More Sustainable Pavement Materials

Pervious concrete pavement is a recognized sustainable solution for urban roads. To enhance mechanical properties of pervious concrete material, in order to allow wider use of this technology, a lot of studies are going on all over the world. The use of a little percentage of fine aggregates is proven to increase the material resistance without an excessive reduction of permeability. This study aimed to evaluate the effect of replacing the fine virgin aggregates with r cycled tire rubber. 14 different mixes were analysed in terms of indirect tensile strength resistance, void content and density. Two different dimensions of crumb rubber were studied, as well as two different dosages, which were applied to different no-fine control mixes. All results were compared with the same control mixes containing natural fine aggregate. The mixes had a fixed granulometric curve but varied in water/cement ratio; this in order to evaluate the effect of recycled rubber depending to w/c ratio of the mix. An image analysis was also conducted to verify the rubber distribution in the mixture and the cracking surfaces. The experimental analysis showed that a correct proportioning of fine sand significantly increased the strength of the material. Moreover, the use of recycled waste tire rubber, gave interesting improvements respect to the no-fine control mixes, even though the developed resistance was lower respect to mixes containing mineral sand. This result was expected because of the cementing property of mineral sand. Although, the important result was that it was possible to use waste tire rubber in pervious concrete, with an appropriate dosage and granular dimension, for increasing the performance of traditional mix design, in order to achieve pavement materials more and more sustainable.

Recycling waste tire rubber by water jet pulverization: powder characteristics and reinforcing performance in natural rubber composites

Abstract Pulverization is a general strategy used prior to any practical application of recycled waste tire rubber (WTR). Mechanical grinding, in use currently, is an inefficient technique due to low-quality rubber powder production and certain indispensable additional pretreatments. The aim of this study is to propose a novel pulverization technique of WTR by ultrahigh pressure water jet. Efficient pulverization of WTR was accomplished by water jet without any pretreatment. Powder characteristics, including particle size distribution (PSD), surface area, thermal behavior and chemical structure changes, were investigated. The curing, mechanical and morphological properties of natural rubber (NR) vulcanizates filled with ground tire rubber (GTR) from water jet pulverization (WJPULV) were evaluated. The results indicate that GTR granules from WJPULV possess a quite fine PSD and large surface area, show similar thermal degradation behaviors to the original WTR and have been partially devulcanized. The improvement of tensile and tear strength of the composites reveals that GTR from WJPULV can be added up to 40 phr without adverse effect. The morphological analysis corroborates the homogeneity of GTR in the NR matrix. All findings confirm that water jet can be an excellent choice for pulverization of WTR.

Recycling of waste tire rubber: Microwave devulcanization and incorporation in a thermoset resin

This study focused on the possibility of recycling Waste Tire Rubber (WTR) to be used as polymer modifier. Thus, WTR was grinded into powder, at ambient temperature, with a disc mill PQ500 and microwave electromagnetic energy was used to devulcanize this powder with the final aim of producing a new composite by its incorporation in a thermoset resin. The influence of the treatment microwave energy on the devulcanization ratio was investigated. FTIR analysis revealed that rupture of Sulfur-Sulfur (SS) and Carbon-Sulfur (CS) bonds have occurred during the treatment. Swelling analysis showed that the microwave treatment can lead to a very significant degree of devulcanization. The Ground Tire Rubber (GTR) and the Devulcanized Ground Tire Rubber (DGTR) were then separately used to prepare epoxy based composites. It appeared that epoxy composites filled with DGTR have better mechanical properties than those filled with untreated GTR. This result agrees with scanning electron microscopy observations which highlighted a better interface coherence between DGTR and epoxy. A complementary analysis pointed out a linear relationship between the rubber modulus and the number of crosslink per chain.

Sustainable approach for recycling waste tire rubber and polyethylene terephthalate (PET) to produce green concrete with resistance against sulfuric acid attack

This work presents a study on the potential use of waste crumb tire rubber and polyethylene terephthalate (PET) particles to produce sustainable concrete. In order to find out the feasibility of such concrete in acidic environment, broad laboratory investigations in terms of crushing load, mass, and ultrasonic wave velocity of tire rubberized concrete (TRC) and tire rubberized PET concrete (TRPC) were conducted and assessed by Taguchi method. Afterwards, the results were compared with normal concrete (NC) and normal PET concrete (NPC). 5, 10, and 15 percent of PET particles along with 15 percent of crumb tire rubber substituted for fine natural aggregate with the aim of reducing the consumption of virgin natural resources and disposing of wastes in a safe, effective, and environmentally friendly approach. The significance levels of the experimental parameters, which indicate how the factors affect the crushing load, mass, and ultrasonic wave velocity, were determined by using Analysis of variance (ANOVA) method. The statistical and analytical results showed that using PET in both NPC and TRPC caused the resistance against sulfuric acid to increase after a 60-day sulfuric acid exposure. Although TRC in comparison to NC had a lower resistance against sulfuric acid, substituting 15 percent of PET particles caused the resistance of TRPC against sulfuric acid to increase significantly and reached that of NPC containing 10 percent of PET. The conclusion is that the waste crumb tire rubber can be employed in concrete in case of using PET particles to compensate for the downside of TRC in acidic environments and, in so doing, a large amount of waste material can be disposed of in a sustainable way.

Experimental Investigation of the Mechanical and Durability Properties of Crumb Rubber Concrete.

Recycling waste tire rubber by incorporating it into concrete has become the preferred solution to dispose of waste tires. In this study, the effect of the volume content of crumb rubber and pretreatment methods on the performances of concrete was evaluated. Firstly, the fine aggregate and mixture were partly replaced by crumb rubber to produce crumb rubber concrete. Secondly, the mechanical and durability properties of crumb rubber concrete with different replacement forms and volume contents had been investigated. Finally, the crumb rubber after pretreatment by six modifiers was introduced into the concrete mixture. Corresponding tests were conducted to verify the effectiveness of pretreatment methods as compared to the concrete containing untreated crumb rubber. It was observed that the mechanical strength of crumb rubber concrete was reduced, while durability was improved with the increasing of crumb rubber content. 20% replacement of fine aggregate and 5% replacement of the total mixture exhibited acceptable properties for practical applications. In addition, the results indicated that the modifiers had a positive impact on the mechanical and durability properties of crumb rubber concrete. It avoided the disadvantage of crumb rubber concrete having lower strength and provides a reference for the production of modified crumb rubber concrete.