Ground Rubber Research Articles

A Modified Ground Rubber and its effect on Physico-mechanical and Dielectric Properties of Nitrile-Butadiene Rubber Composites For a Green Environment

A Modified Ground Rubber and its effect on Physico-mechanical and Dielectric Properties of Nitrile-Butadiene Rubber Composites For a Green Environment

CHARACTERIZATION OF ASPHALT MODIFICATION USING GROUND RUBBER AND REACTIVE RUBBER NR-g-MA AS COMPATIBILIZER

This study aims to improve the quality of asphalt by adding ground tyre rubber (GR) and reactive rubber (NR-g-MA) as compatibilizers of asphalt-rubber mixability. The use of GR has been widely used to improve the performance of asphalt and extend the service life of asphalt. The NR-g-MA used was the product of the copolymerization of SIR-20 rubber grafts with maleic anhydrous (MA) through a melting process in an internal mixer. Mixing of GR in asphalt was carried out in an external mixer with composition of asphalt/GR 95/5 phr at the temperature of 180oC for 90 minutes. The performance of asphalts were measured based on conventional test of penetration and softening point. The rheological properties of asphalt were measured using a Dynamic Shear Rheometer (DSR). Important parameters of the rheological properties measured are complex shear modulus (G*) and phase angle (d). Asphalt resistance to the permanent deformation (rutting) were determined on asphalt that has undergone a short-term aging process in a rolling thin film oven (RTFO) and measured at high temperatures (58-82OC). Fatigue crack resistance was tested on asphalt that has undergone a long-term aging process using the method of pressure aging vessel (PAV) and measured at low temperatures (25-31OC). Asphalt-GR mixtures' chemical, thermal and morphological properties were studied using ATR-FTIR, DSC/TGA, and SEM respectively. The results showed that adding used ground rubber (GR) decreased the penetration value by 9.93 – 18.87% and increased the softening point of asphalt from 5.57 – 11.40%. Rheological analysis showed that the addition of GR and compatibilizer NR-g-MA increase the value of complex shear modulus (G*) and decrease the phase angle (d) of the asphalt. The addition of ground rubber and reactive rubber of NR-g-MA to asphalt improve the performance of asphalt because it has rutting resistance at high temperatures as well as improves asphalt cracking resistance at low-temperature measurements. The addition of NR-g-MA reactive rubber to modified asphalt ground rubber can increase the mixability of asphalt-rubber used tires.

Recycled Tire Fibers Used as Reinforcement for Recycled Polyethylene Composites

This study proposes a simple approach to separate most rubber particles from recycled tire fibers (RTFs) and to determine their rubber content using thermogravimetric analysis (TGA)/calcination. Furthermore, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), and Fourier transform infrared spectroscopy (FTIR) analyses are used to investigate the separation process and materials compositions. Afterwards, a series of composites based on recycled post-consumer low-density polyethylene (rLDPE) with clean fiber (CF) and residual ground rubber particles (GR) is prepared at different filler concentrations (0–30%) via extrusion compounding before using compression molding and injection molding for comparison. In all cases, injection molding leads to higher strength and modulus but lower elongation at break. The results show that incorporating 30 wt.% of CF into rLDPE yields a remarkable improvement in tensile strength (15%), tensile modulus (192%) and flexural modulus (142%). On the other hand, the incorporation of up to 30 wt.% of GR results in a reduction in both tensile strength and flexural modulus by 15%, confirming the critical role of the cleaning process for RTF in achieving the best results.

A novel epoxy adhesive with ground rubber tire powder and carboxylated multiwalled carbon nanotubes

AbstractThe present study was an attempt to improve the toughness, mechanical and adhesion properties, and thermal stability of a two‐phase epoxy DGEBA/Resole phenolic resin through the use of carboxyl‐modified multi‐walled carbon nanotubes (c‐MWCNTs) and ground rubber tire (GRT) powder. The effect of a hybrid reinforcement containing GRT and c‐MWCNT blend on the mechanical properties, thermal stability, and microstructure of the epoxy‐phenolic adhesive were evaluated by tensile test, TGA, and FESEM, respectively. The formulated adhesive was utilized in a lap joint metal to a composite in order to peruse the adhesion features, where the composite was an epoxy resin reinforced with carbon fibers and the metal was stainless steel 316 L. According to the tensile test, there were 32% rise in tensile strength, 27% rise in modulus, and a 64% rise in toughness with adding 0.5% wt c‐MWCNTs and 15 phr waste GRT powder to the epoxy‐phenolic matrix. Furthermore, adding 1% wt c‐MWCNTs of nanoparticles and GRT powder has resulted in a 15% increase in lap shear strength. It also can be seen that thermal stability for the formulated samples has experienced an upward trend compared to the neat epoxy composite.Highlights Epoxy adhesives based on GRT Powder, c‐MWCNTs particles and phenolic resin have been successfully prepared. The hybrid uses of GRT Powder and c‐MWCNTs particles can synergistically increase the tensile and lap shear strength The addition of c‐MWCNT nano particles and GRT Powder in an epoxy adhesive can have a dramatic rise in the toughness system compared to the neat epoxy adhesive. Maximum degradation temperature of the produced newly adhesive has increased considerably in contrast with the neat epoxy adhesive.

Strength-Gain Characteristics and Swelling Response of Steel Slag and Steel Slag–Fly Ash Mixtures

The shear strength and stiffness characteristics of steel slag indicate that it can potentially be utilized as a competent base/subbase material of bound and unbound pavement layers. However, concerns with respect to the utilization of steel slag remain due to its long-term swelling, corrosivity, and leaching characteristics. In this study, long-term swelling and corrosivity tests were performed on basic-oxygen-furnace steel slag (BOFSS) and electric-arc-furnace ladle steel slag [EAF(L)SS] generated in Indiana, USA. In order to reduce the 1D swelling strains of these slags, 5%, 10%, and 20% Class C fly ash (CCFA) and 10% ground rubber replacement ratios were used to prepare steel slag mixtures for testing. The improvement due to CCFA replacement was evaluated by performing unconfined compression and long-term swelling tests on selected steel slag–CCFA mixtures. The seven-day unconfined compression strengths of 90% EAF(L)SS + 10% CCFA and 90% BOFSS + 10% CCFA mixtures were 2,387 and 3,768 kPa, respectively. After nine months of monitoring, the maximum 1D swelling strains of soaked samples of BOFSS and EAF(L)SS mixtures prepared with 10% CCFA replacement were 0.1% or less. The unconfined compression and swelling test results for the steel slag–CCFA mixtures indicated superior strength gain characteristics and negligible swelling strains with time than for steel slags.

Static and cyclic performance of polyurethane foam adhesive bound soil–rubber mixtures under drained conditions

The major drawbacks of a railway track include noise, vibration, and aggravated track degradation. Resilient mats and asphalt have been increasingly used in recent years to mitigate this noise and vibration. However, these materials are quite expensive. Conventional asphalt is very stiff and brittle, making it more prone to cracking. The present work aims to develop a novel material that can be used as a base layer in ballasted and slab tracks. The current research proposes a sustainable and resilient base course layer comprising ground rubber (GR) and polyurethane foam adhesive (PFA). In this study, the performance of GR embedded in the sand is investigated. The use of PFA-treated sand with and without GR is then explored. The optimum dosage of PFA for soil and GR for treated and untreated soil is recommended based on static direct simple shear (SDSS) and cyclic direct simple shear (CDSS) tests. SDSS tests were performed to evaluate the monotonic performance of all mixtures. CDSS tests were performed to assess the long-term performance of these different mixes under repeated cyclic loading (50,000 load cycles) and varying cyclic shear stress amplitude. It is shown that PFA helps reduce the settlement and enhance soil shear strength, while GR increases the damping ratio of the soil. The optimum dosage of PFA is recommended 10%. The optimum GR content for untreated and PFA-treated soil is recommended 5 and 10%, respectively.

Effect of Temperature on the Mechanical Properties of the Highly Filled Composites Based on Polypropylene and Ground Rubber Scrap

The mechanical properties of the dispersion-filled composites based on polypropylene (PP) and ground rubber scrap are studied in the temperature range from 40 to 120 °C. The content of the rubber particles is varied from 40 to 80 wt %. The peculiarities of the realization of a brittle-to-ductile or ductile-to-ductile transition in the composites are determined. The change in the deformation behavior occurs through the intermediate tension of the composite with the formation of several delocalized necks in the range of the filler concentrations. The negative effect of large particles during macrouniform tension of rubber plastics is shown for the first time. Their presence in the composite composition facilitates its fracture while the matrix polymer is underloaded (the effect of a single defect).

Performance of prototype seismic isolators reinforced with fiber and a recycled rubber tire matrix

Seismic isolators are passive control devices that reduce the energy transferred from an earthquake to the superstructure, this avoiding damage to building elements. Seismic isolators are classified according to their connection to the structure; for example, unbonded isolators lack mechanical connections with the building. Unbonded fiber-reinforced elastomeric isolators (U-FREIs) are formed of intercalated layers of bidirectional polyester mesh used as reinforcement and agglomerated ground rubber from end-of-life tires (ELTs) as an elastomeric matrix. This paper presents the mechanical behavior of U-FREIs built at a reduced scale to provide an affordable alternative for the mitigation of seismic forces that affect low-rise buildings. The isolators were designed for a low-rise residential frame structure located in an area of high seismic hazard and were subjected to shear and compression tests to characterize their mechanical behavior. The experimental results show good behavior of the prototypes with respect to standards and design requirements.

Tire Ground Rubber Biodegradation by a Consortium Isolated from an Aged Tire.

Rubber is a natural product, the main car tire component. Due to the characteristics acquired by this material after its vulcanization process, its degradation under natural conditions requires very long times, causing several environmental problems. In the present work, the existence of a bacterial consortium isolated from a discarded tire found within the Socabaya River with the ability to degrade shredded tire rubber without any chemical pretreatment is explored. Taking into consideration the complex chemical composition of a rubber tire and the described benefits of the use of pretreatments, the study is developed as a preliminary analysis. The augmentative growth technique was used, and the level of degradation was quantified as a percentage through the analysis of microbial respiration. Schiff’s test and the use of comparative photographs of scanning electron microscopy (SEM) were also used. The consortium using next generation genetic sequencing was analyzed. A 4.94% degradation point was obtained after 20 days of experimentation, and it was found that the consortium was mostly made up with Delftia tsuruhatensis with 69.12% of the total genetic readings of the consortium and the existence of 15% of unidentified microbial strains at the genre level. The role played by the organisms in the degradation process is unknown. However, the positive results in the tests carried out show that the consortium had action on the shredded tire, showing a mineralization process.

Processing and Mechanical Properties of Highly Filled PP/GTR Compounds.

Ground rubber from automobile tires is very difficult to recycle due to the cross-linking of the macromolecules and thus the lack of thermoplastic properties. The research consisted of assessing the processing possibility via the injection of highly filled PP/GTR compounds modified with 1.5 wt.% 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane. GTR dosing ranged from 30 wt.% up to 90 wt.%. The evaluation of the processing properties of the obtained materials was carried out on the basis of the melt flow index test results and the signals recorded during processing by the injection molding by temperature and pressure sensors placed in the mold. The influence of the applied modifier on the changes in the mechanical properties of PP/GTR was determined with hardness, impact and static tensile tests. Moreover, thermal properties were obtained by the differential scanning calorimetry method. It has been found that it is possible to efficiently process compounds with high GTR content using injection molding. The presence of the filler allows to significantly reduce the cooling time in the injection mold and thus the time of the production cycle. It has been confirmed that 2.5-dimethyl-2.5-di-(tert-butylperoxy)-hexane modifies the rheological properties of PP and thus the PP/GTR composition. The lower viscosity of the matrix results in a more accurate bonding with the developed surface of the GTR grains, which results in better mechanical properties of the rubber-filled polypropylene.

Simultaneous effect of CaCO3 nanoparticles and waste ground rubber tire powder on forced vibration of polypropylene nanocomposite plates: An experimental investigation

In this study, the effect of the simultaneous incorporation of different contents of CaCO3 nanoparticles (NPs) and waste ground rubber tire powder (WGRT) on the forced vibration behavior of polypropylene (PP) was experimentally investigated. Hammer test with modal analysis was performed to investigate the vibrational behavior of the composite plates with one edge clamped (CFFF) support condition. Microstructural assessment of composites using Field Emission Scanning Electron Microscope (FESEM) images showed that a rise in CaCO3 nanoparticles in small weight percentages led to better dispersion and a decline in the tire phase size in the small weight percentage of WGRT. Moreover, a comparison of the modal analysis results revealed that all ternary composites, except in the first mode, had a higher damped natural frequency than pure PP. The damping ratio of all ternary composites, especially in the first and second modes, was higher than pure PP, which is due to the combined effect of WGRT and CaCO3 nanoparticles in increasing energy dissipation and damping of composites.

Morphological, mechanical, and physical properties of ground rubber tire thermoplastic elastomer/rubberwood sawdust composites: Effects of composition contents and rubber types

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

Potential Valorization of Waste Tires as Activated Carbon-Based Adsorbent for Organic Contaminants Removal.

The present study investigates the potential of waste tires to produce a valuable adsorbent material for application in wastewater treatment. In the first stage, the pyrolysis of ground rubber tire was explored using non-isothermal and isothermal thermogravimetric analysis experiments. The effect of operating parameters, such as heating rate and pyrolysis temperature, on the pyrolysis product yields was considered. The slow pyrolysis of ground rubber tire was taken up in a large-scale fixed-bed reactor for enhanced char recovery. Four pyrolysis temperatures were selected by thermogravimetric data. The product yields were strongly influenced by the pyrolysis temperature; at higher temperatures, the formation of more gases and liquid was favored, while at lower pyrolysis temperatures, more char (solid fraction) was formed. The produced chars were characterized in terms of mineral composition, textural properties, proximate analysis, and structural properties to identify the relationships between the pyrolysis temperature and the char properties. In a second step, a series of activated chars were prepared, starting from the pyrolytic chars via chemical and/or physical activation methods. Then, the activated chars were characterized and tested as adsorbents for atrazine and ibuprofen. Adsorption experiments in aqueous media were carried out in a small-scale batch reactor system. Chemical activation seems appropriate to significantly reduce the inorganic compounds initially present in ground rubber tire and contribute to an important increase in the surface area and porosity of the chars. Adsorption experiments indicated that chemically activated chars exhibit high aqueous adsorption capacity for atrazine.

Performance evaluation of Asphalt Rubber Gap-graded mixture

One of the most successful means of improving paving performance is by the use of Crump Rubber (CR). Increased demand for Asphalt Rubber Gap-graded (AR-Gap) mixtures as a pavement material has resulted from improvements in the basic asphalt binder as well as environmental advantages and improved performance in recent years. A number of agencies and researchers conducted AR-Gap mix studies to evaluate the design and performance of AR-Gap mixtures. In this study, the most recent research and practices in the design of AR-Gap mixtures were reviewed, and the performance characteristics of these mixtures were also summarized. In addition, the positive effect of adding ground rubber on the performance of the mixtures, including the effect on fatigue cracking, drainage, moisture susceptibility and permanent deformation is also reviewed. In conclusion, future aims in the building of AR-Gap pavement and performance potential were discussed, which will assist it in becoming a viable long-term pavement choice in the future. Based on the results of the evaluation process, it was discovered that there is still potential to improve the current design state of AR-Gap mixtures as well as the effect of rubber inserts in improving the performance of the mix.

Performance optimization of ground rubberized green concrete with metakaolin

The disposal of waste vehicle tires is an environmental and health problem, as their recycling is very difficult. One of the effective ways of recycling is using these tires as partial replacement of Portland cement in construction industry. In this study, a systematic experimental study (by making 810 laboratory samples) is performed on concrete made with finely ground rubber (GR) and metakaolin (MK) as partial replacements of cement to investigate the compressive strength, splitting tensile strength, flexural strength, water absorption, and dry unit weight. The main goal of this study is to achieve the optimal proportions of concrete incorporating GR and MK by maximizing mechanical strengths while minimizing the water absorption (WA) of concrete. To do so, 7 concrete mixtures containing GR are produced with 3 different cement contents: 350, 400, and 450 kg/m3 in conjunction with 2 different water-cement ratios: 0.45 and 0.50. Also, 1 concrete mix is used to optimize the concrete with hybrid blends of GR and MK by employing the response surface methodology (RSM). GR and MK are applied as partial replacements of Portland cement in ranges of 0–30 vol% and 0–20 vol%, respectively. The results show that the use of GR and MK in concrete has a significant effect on its mechanical and durability properties and, thus, reduces the cement consumption which can contribute to decreasing the negative impacts of cement production on the environment. According to the optimization results, 4.2% and 19.5 vol% replacements of cement with GR and MK, respectively, can be considered as the optimum mixture compositions of hybrid concrete to maximize compressive and splitting tensile strengths by about 1–4% and 6–8%, respectively, while minimizing WA by about 48%. Depending on the flexural strength results, the amounts are changed into 1.8% and 14.7% while the flexural strength increases by about 11%.

Effect of Waste Ground Rubber Tire Powder on Vibrational Damping Behavior and Static Mechanical Properties of Polypropylene Composite Plates: An Experimental Investigation

Effect of Waste Ground Rubber Tire Powder on Vibrational Damping Behavior and Static Mechanical Properties of Polypropylene Composite Plates: An Experimental Investigation

Effect of Ground Tire Rubber (GTR) Particle Size and Content on the Morphological and Mechanical Properties of Recycled High-Density Polyethylene (rHDPE)/GTR Blends

This work investigates the effect of ground rubber tire (GRT) particle size and their concentration on the morphological, mechanical, physical, and thermal properties of thermoplastic elastomer (TPE) blends based on recycled high-density polyethylene (rHDPE). In our methodology, samples are prepared via melt blending (twin-screw extrusion followed by compression molding) to prepare different series of blends using GTR with three different particle sizes (0–250 μm, 250–500 μm, and 500–850 μm) for different GTR concentrations (0, 20, 35, 50, and 65 wt.%). The thermal properties are characterized by differential scanning calorimeter (DSC), and the morphology of the blends is studied by scanning electron microscopy (SEM). The mechanical and physical properties of the blends are investigated by quasi-static tensile and flexural tests, combined with impact strength and dynamic mechanical analysis (DMA). The SEM observations indicate some incompatibility and inhomogeneity in the blends, due to low interfacial adhesion between rHDPE and GTR (especially for GTR > 50 wt.%). Increasing the GTR content up to 65 wt.% leads to poor interphase (high interfacial tension) and agglomeration, resulting in the formation of voids around GTR particles and increasing defects/cracks in the matrix. However, introducing fine GTR particles (0–250 μm) with higher specific surface area leads to a more homogenous structure and uniform particle dispersion, due to improved physical/interfacial interactions. The results also show that for a fixed composition, smaller GTR particles (0–250 μm) gives lower melt flow index (MFI), but higher tensile strength/modulus/elongation at break and toughness compared to larger GTR particles (250–500 μm and 500–850 μm).

MECHANICAL PROPERTIES OF CEMENT CONCRETES INCORPORATING GROUND TIRE RUBBER

This article proves the possibility of replacing aggregates in concrete mixtures with rubber, which is obtained by grinding used car tires. It was found that the replacement of crushed coarse aggregate in the amount of 10 vol.% with ground rubber from used car tires increases the bending strength by 23% The compressive strength does not change significantly. When working in the subcritical stage of deformation (until the macrocrack shifts), concrete with the replacement of the coarse aggregate is preferred, as the energy consumption of which for elastic deformation (We) exceeds the base concrete. Analysis of the supercritical stage of deformation (macrocrack propagation) reveals that the replacement of fine and coarse aggregates negatively affects the value of total energy consumption for local static deformation in the main crack zone (Wl), which is by 1.35 and 1.14 times lower than the control concrete.

Liquefaction Resistance of Silty Sand with Ground Rubber Additive

Abstract The contractive behavior and flow failure in saturated binary granular soils have been studied by many as functions of their physical properties [gradation, mean particle size, fines conte...

Improved Shear Strength Performance of Compacted Rubberized Clays Treated with Sodium Alginate Biopolymer.

This study examines the potential use of sodium alginate (SA) biopolymer as an environmentally sustainable agent for the stabilization of rubberized soil blends prepared using a high plasticity clay soil and tire-derived ground rubber (GR). The experimental program consisted of uniaxial compression and scanning electron microscopy (SEM) tests; the former was performed on three soil-GR blends (with GR-to-soil mass ratios of 0%, 5% and 10%) compacted (and cured for 1, 4, 7 and 14 d) employing distilled water and three SA solutions—prepared at SA-to-water (mass-to-volume) dosage ratios of 5, 10 and 15 g/L—as the compaction liquid. For any given GR content, the greater the SA dosage and/or the longer the curing duration, the higher the uniaxial compressive strength (UCS), with only minor added benefits beyond seven days of curing. This behavior was attributed to the formation and propagation of so-called “cationic bridges” (developed as a result of a “Ca2+/Mg2+ ⟷ Na+ cation exchange/substitution” process among the clay and SA components) between adjacent clay surfaces over time, inducing flocculation of the clay particles. This clay amending mechanism was further verified by means of representative SEM images. Finally, the addition of (and content increase in) GR—which translates to partially replacing the soil clay content with GR particles and hence reducing the number of available attraction sites for the SA molecules to form additional cationic bridges—was found to moderately offset the efficiency of SA treatment.