Scrap Tire Rubber Research Articles

Effect of layering and pre-loading on the dynamic properties of sand-rubber specimens in resonant column tests

AbstractSeveral studies show that scrap tyre rubber mixed with sand is an effective and sustainable method for mitigating vibrations. The dynamic and cyclic response of this composite soil has already been investigated. However, layered sand-rubber configurations have not been considered yet. This study reports findings of resonant column tests on three types of specimen: (a) sand-only or rubber-only, (b) layered sand-rubber, and (c) sand-rubber mixtures. The analysis allowed for an evaluation of the maximum shear modulus and its degradation with strain over a wide range of confining stress and shear strain. The evolution of the damping ratio with strain was determined analogously. Effects of pre-loading and pre-straining were also considered. The results show that the behaviour of layered specimens is much more similar to that of pure rubber than to sand-rubber mixtures, with very low shear modulus values, smaller degradation of stiffness with strain and pre-loading, and higher damping. For example, at the confining stress of 100 kPa and rubber content of 0/33.3/50/67.7/100% by volume, the small strain shear moduli for sand-rubber mixtures are equal to 98.3/30.4/15.4/7.1/1.3 MPa and 98.3/3.6-4.2/2.4-2.8/2.1/1.3 MPa for sand-rubber layered specimens, depending on the arrangement of layers. A shear beam model is shown to be adequate for calculating the response of the layered specimens comprising layers of large stiffness contrast.

Impact response and compression-after-impact properties of foam-core sandwich composites incorporating scrap tyre rubber particles

Integrating scrap rubber particles as fillers into polymer matrix composites offers a cost effective and environmentally sustainable pathway to manage tyre waste through the creation of value-added products. This research explores the low-velocity impact (LVI) response and compression after impact (CAI) properties of rubberised foam-core glass fibre-reinforced epoxy (GFRE) sandwich composites. Syntactic foam cores integrated with rubber particles were manufactured using vacuum-assisted resin transfer moulding (VARTM). The compression properties of rubberised foam core, vital for resisting impact damage during LVI, were examined. Results show more than 40% reduction in compression strength and modulus of the syntactic foam upon the inclusion of 33 wt.% rubber particles. The LVI response and residual compression properties of rubberised foam-core composites were also evaluated. Rubberised foam cores caused a marginal reduction in the peak impact force and led to approximately 60% reduction in the delamination area. The pre-impact compression strength was unaffected by rubber particles within the core as the GFRE face sheets carried most of the compression load. Post-impact compression strength was slightly higher in rubberised foam-core composites due to reduced delamination. Digital Image Correlation (DIC) analysis tracking of the strain evolution during CAI experiments revealed the stress-raising effect of the impact damaged region. This study showcases sustainable scrap tyre management through the inclusion of rubber particles into foam-core composites without substantially reducing in-plane compression properties before or after low-velocity impact.

Synergistic effects of steel fiber and rubberized aggregates on concrete properties

The drive for more sustainable and environmentally friendly construction practices has resulted in revolutionary concrete production methods. One way is to include scrap rubber tires (contributing significantly to environmental pollution) into concrete mixtures to increase deformability. This study investigates the impact of surface-treated waste tire rubber (which partially replaces natural coarse aggregates with 5%, 10%, and 15% by weight) and industrial steel fiber (as reinforcement by including 0.5, 1, and 1.5% volume fractions) in concrete. Twelve concrete mixtures were prepared as test specimens. The replacement percentage was then determined using the compressive strength test results for additional surface treatment with three different alkaline solution (NaOH) concentrations (5%, 10%, and 15%) for 72 h. Thus, the hardened concrete properties were analyzed using compressive strength, flexural strength, and toughness; whereas the fresh qualities of equivalent concrete mixtures were evaluated using concrete slump. The findings revealed that, while partial replacement had a negative impact on the mechanical properties of the concrete, it was possible to produce rubberized concrete with better mechanical properties than conventional concrete when the partial replacement was less than 5%, treated with 10% alkaline solution, and reinforced with 1.5% steel fibers. The study’s findings illustrate the potential of these combinations for use in concrete pavement and slab applications.

Predicting the modulus of elasticity of clayey soil composites reinforced with scrap tire rubber fibers using a composite material model

In this study, composite material models are used to predict the modulus of elasticity of a composite consisting of scrap tire rubber fibers and clayey soils. The calculated modulus of elasticity is compared with the reference modulus obtained from experimental testing. Predicting the effective mechanical properties of composites is crucial in situations where testing is impractical, challenging, or costly. The analysis involves various approaches within the elasticity framework, utilizing rheological models such as Voigt, Reuss, Hirsch-Dougill, Popovics, Halpin-Tsai, Hashin, and the Bache & Napper–Christensen estimation. These models aim to predict the effective Young's modulus of the composite system comprising soil and rubber fibers. The maximum discrepancies observed are 10.66%, 12.71%, and 12.98% for both soils. Voigt, Hashin, and Bache estimations provide highly accurate predictions of the effective Young's modulus, showing excellent agreement with experimental results across different fiber volume fractions ranging from 10% to 50%.

A low-cost bonded scrap tire rubber isolator in rural regions: Experimental, numerical and theoretical analysis on mechanical behavior

The utilization of low-cost scrap tire pads (STP) made from recycled tires presents a promising alternative to traditional rubber isolators (i.e., fiber-reinforced elastomeric isolators) in rural construction. However, the STP was limited in application to practicing structures due to stability with a shear strain level of 100 % and the significant variability of the mechanical behavior at the same parameters. For these issues, this paper presents a bonded scrap tire rubber isolators (BSTRIs), based on earthquake demand parameters for rural area buildings. In addition, a series of vertical compression and horizontal shear tests were conducted to evaluate the dependency of mechanical behavior on surface pressure (σ0), the first and the second shape factor (S1 and S2). Then, a finite element (FE) model of BSTRIs was developed and validated. The experimental and FE results show that the σ0, S1, and S2 overwhelmingly effect on mechanical behavior (i.e., critical pressure, vertical stiffness, horizontal stiffness, and damping ratio). Moreover, the new theoretical formulations on critical pressure, vertical stiffness, and horizontal stiffness were developed to evaluate the stability of BSTRIs. Finally, based on experimental result, a nonlinear dynamic response was conducted including the BSTRIs-supported and based-fixed unreinforced masonry (URM) buildings under 22 far-field and 28 near-field seismic excitations. The results indicated that the base shear of the BSTRIs-supported URM were decreased by 66.5 % and 50.1 % in far- and near-field record, respectively, compared with the response of the fixed-base URM building.

Assessing the rheological properties of bio modified asphalt cement

The production of asphalt cement binder in Iraq is conducted through the distillation of crude oil. The byproduct of such distillation is the asphalt cement which does not practice any further processing further processing of the binder is considered vital to control its physical properties and chemical composition. The implementation of bio-modifiers before using such asphalt cement binder for paving work is a sound practice to enhance its sustainability and reserve the required rheological properties. In the present study, the asphalt cement binder was modified by implementation of extender oil (used diesel engine oil) and scrap tire rubber. The aim of this work is to improve and provide a sustainable and proper rheological quality of the binder for paving work. Various percentages of scrap tire rubber and extender oil have been tried to optimize the modifiers which can exhibit a suitable control on the required rheological properties of the asphalt binder such as the stiffness modulus, its temperature susceptibility in terms of penetration index and penetration viscosity number, and temperature of equivalent stiffness of the binder. The stiffness of asphalt cement binder was digested at hot, moderate, and cold environments. It was observed that the implementation of extender oil was able to reduce the penetration index (PI) by 36.3%, 54.5%, and 27.2% when 15%, 10%, and 5% of extender oil by weight of the mixture were added respectively to the control binder. The addition of scrap tire rubber to the binder-oil mixture was able to reduce the PI up to 10% of rubber content and exhibited further control of the temperature susceptibility of the binder. It can be revealed that the extender oil increases the negative values of penetration viscosity number (PVN) while the scrap tire rubber can improve the PVN of the binder. When high percentage of extender oil 15% is implemented, the stiffness of the binder declines by 50%, 90%, and 75% when the testing temperature change from 4 to 25, and 60 ℃ respectively. It was concluded that implication of 15% of scrap tire rubber and 15% of extender oil into the asphalt cement binder produced by Qayarah oil refinery is recommended to provide a sustainable binder for pavement, control its temperature susceptibility, and provide a binder with lower prone to pavement distresses.

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

Microbially Mediated Rubber Recycling to Facilitate the Valorization of Scrap Tires.

The recycling of scrap tire rubber requires high levels of energy, which poses challenges to its proper valorization. The application of rubber in construction requires significant mechanical and/or chemical treatment of scrap rubber to compatiblize it with the surrounding matrix. These methods are energy-consuming and costly and may lead to environmental concerns associated with chemical leachates. Furthermore, recent methods usually call for single-size rubber particles or a narrow rubber particle size distribution; this, in turn, adds to the pre-processing cost. Here, we used microbial etching (e.g., microbial metabolism) to modify the surface of rubber particles of varying sizes. Specifically, we subjected rubber particles with diameters of 1.18 mm and 0.6 mm to incubation in flask bioreactors containing a mineral medium with thiosulfate and acetate and inoculated them with a microbial culture from waste-activated sludge. The near-stoichiometric oxidation of thiosulfate to sulfate was observed in the bioreactors. Most notably, two of the most potent rubber-degrading bacteria (Gordonia and Nocardia) were found to be significantly enriched in the medium. In the absence of added thiosulfate in the medium, sulfate production, likely from the desulfurization of the rubber, was also observed. Microbial etching increased the surface polarity of rubber particles, enhancing their interactions with bitumen. This was evidenced by an 82% reduction in rubber-bitumen separation when 1.18 mm microbially etched rubber was used. The study outcomes provide supporting evidence for a rubber recycling method that is environmentally friendly and has a low cost, promoting pavement sustainability and resource conservation.

Experimental and Computational Analyses of Sustainable Approaches in Railways

Railway transportation is widely recognized as an environment-friendly and sustainable means for conveying freight and passengers over long distances. This article investigates the effectiveness of utilizing scrap tire rubber granules and geosynthetics to enhance track performance in response to the growing demands for railway transport and the consequent escalation of train-induced loading. A multi-faceted methodology, incorporating experimental, numerical, and analytical techniques, is employed to examine the efficacy of these sustainable approaches. Results from three-dimensional (3D) finite element (FE) analyses conducted on slab tracks for high-speed railways reveal that the addition of a resilient layer, comprising scrap tire rubber granules, reduces vertical stress within the track substructure. Laboratory investigations on an innovative composite material consisting of soil, scrap rubber granules, and polyurethane demonstrate its potential to enhance track performance. Findings from two-dimensional (2D) FE analyses conducted on pile-supported railway embankments highlight an enhanced transfer of load to the pile head following the installation of a geogrid layer at the embankment base. Finally, the results from the analytical approach indicate a reduction in track settlement and a decrease in the track geometry degradation rate on reinforcing the ballast layer with 3D cellular geoinclusion. The novelty of this study lies in the comprehensive assessment of the innovative composite material under drained and cyclic loading conditions, the investigation of the influence of train loading on geosynthetic tension and the load transfer mechanism in railway embankments, and the development of an innovative computational methodology capable of assessing the effectiveness of 3D cellular inclusions in improving the ballasted railway track performance. The findings from this article underscore the effectiveness of these sustainable approaches in mitigating the challenges posed by increased loads on railway tracks, providing valuable insights for the ongoing efforts to optimize railway transportation infrastructure.

Effect of Natural Pozzolana and Scrap Tire Rubber Mixture on Compacted Clayey Soils

Effect of Natural Pozzolana and Scrap Tire Rubber Mixture on Compacted Clayey Soils

Physical Chemistry Supports Circular Economy: Toward a Viable Use of Products from the Pyrolysis of a Refuse-Derived Fuel and Granulated Scrap Tire Rubber as Bitumen Additives

The production and maintenance of road pavements consume resources and produce wastes that are disposed of in landfills. To make more sustainable this activity, we have envisioned a method based on a circular use of residues (oil and char) from municipal solid waste pyrolysis as useful additives for producing improved asphalts and for recycling old asphalts to generate new ones, reducing at the same time the consumption of resources for the production of new road pavements and the disposal of wastes to landfills. This work aims to show the feasibility of the integration of two processes (thermal treatment of municipal solid waste on one side, and that of road pavement production on the other side) where the products deriving from waste pyrolysis become added-value materials to improve the quality of road pavements. In this contribution, we presented the effect of pyrolysis product addition on asphalt binder (bitumen) preparation and aging. Solid and liquid products, deriving from the pyrolysis of two kinds of wastes (refused derived fuel (RDF) and granulated rubber tyre waste), have been used for the preparation of asphalt binder samples. Rheological tests have been performed to determine the mechanical properties of neat asphalt binder (bitumen) and those enriched with pyrolysis derived products. Measurements to evaluate possible anti-aging effects have been also performed. The collected results indicate that char addition strengthens the overall bitumen intermolecular structure while bio-oil addition exerts a rejuvenating activity.

Review on the Role of Rubber on the Performance of Concrete

Due to the rapid development of the vehicle manufacturing industry, the hazards caused by scrap tire rubber have become one of the serious problems faced by people today. Rubber concrete is made of waste rubber into different particle sizes to replace the fine aggregate in ordinary concrete formed by a new type of composite material, for the disposal of waste tires and rubber opened up a new way, so that waste rubber can be reused. Rubber concrete compared to ordinary concrete has Light weight, good elasticity, high toughness, ductility, impact resistance, good damping, good frost resistance, but its strength is reduced. From the perspective of mechanical properties, durability and modification treatment, the article introduces the research progress of its compressive strength, frost resistance, carbonation resistance, modification treatment, etc., which provides a method for rubber concrete to be used in a wider range of practical projects.

Flexural Behavior of Reinforced Rubberized Reactive Powder Concrete Beams under Repeated Loads

Non-biodegradability of rubber tires contributes to pollution and fire hazards in the natural environment. In this study, the flexural behavior of the Rubberized Reactive Powder Concrete (RRPC) beams that contained various proportions and sizes of scrap tire rubber was investigated and compared to the flexural behavior of the regular RPC. Fresh properties, hardened properties, load-deflection relation, first crack load, ultimate load, and crack width are studied and analyzed. Mixes were made using micro steel fiber of the straight type, and they had an aspect ratio of 65. Thirteen beams were tested under two loading points (Repeated loading) with small-scale beams (1100 mm, 150 mm, 100 mm) size. The fine aggregate is replaced by 5, 10, and 15%, respectively, with crumb rubber. While replacement of silica fume was 10, 20, 30, and 50%, respectively, with very fine rubber. Also, chip rubber was added to the mixture as coarse aggregate with 5, 10, and 15%. Five tested beams were chosen as case studies to analyze and compare the results of the ABAQUS software with the experimental results. The results showed that the flexural behavior of RRPC beams that contains rubber was acceptable when compared with the flexural behavior of the RPC beam (depending on load-carrying capacity). The crack width was decreased by including waste rubber and steel fibers. There is a satisfactory agreement between the results of the numerical analysis and the results of the experimental testing. Slight ultimate load differences are targeted between the effects of the monotonic loading and the repeated loading.

Theoretical calculation model for the thermal conductivity of scrap tire rubber–sand mixtures based on soil components

Theoretical calculation model for the thermal conductivity of scrap tire rubber–sand mixtures based on soil components

Use of Waste Tyre in Concrete

Abstract: Waste tyre rubber disposal has become a major environmental concern in all parts of the world, posing a serious threat to the environment. One potential application for scrap tyre rubber is to mix it into concrete to replace some of the natural material. Every year, an estimated 1000 million tyres reach the end of their useful lives, with another 5000 million predicted to be thrown on a regular basis by 2030. Currently, only a small portion is recycled, and millions of tyres are just stacked, landfilled, or buried. This not only reduces pollution caused by waste tyres, but it also reduces the usage of conventional aggregate, which is limited in supply.As per the mix design specifications, the rubber pieces (rubber aggregate) were sieved through a 25 mm sieve and held at a 20 mm sieve before being added to the concrete mix at 3.5,5.5,7.5 percent by weight of the aggregate. This study investigates the beneficial impact of waste tyre rubber particles on several concrete characteristics. The used rubber scraps are obtained through the mechanical trituration of used tyres from automobiles and trucks. They have long been researched for resource reutilization as an aggregate in concrete, resulting in the 'Rubcrete mix,' which may be easily used in a variety of applications with promising results. Rubcrete produces a finished product with good mechanical qualities and also represents an efficient and cost-effective method of recycling waste tyres. The purpose of this paper is to report the findings of an experimental examination into the ideal types and quantities of aggregates in concrete mixtures for engineering purposes. The following parameters were investigated: density of rubber aggregates, workability, air entrapment, and compressive strength. In rubberized concrete mixtures, three types of rubber particles (ash rubber, crumb rubber, and tyre) were utilised to partially or totally replace natural aggregates.

Strength and consolidation index parameters of stabilise clay soil using scrap rubber tyre

Scrap rubber tyres are one of the synthetic fibre materials that can be used as a soil stabilizer. This study looks into the effects of scrap rubber tyres as a soil stabiliser on clay soil. Soil samples were collected in Kota Kinabalu, and the scrap rubber tyre was passed through a 2 mm passing sieve. Three experimental tests were carried out: compaction, consolidation, and an unconfined compression test (UCT). During the compaction test, the maximum dry density (MDD) and optimum moisture content (OMC) parameters were determined using the proctor standard penetration test. The shear strength of all soil samples was determined using UCT. The consolidation test also looks at the compressibility index and swelling index. Four soil sample configurations were prepared, one as a control sample and three with different soils mixed with varying percentages of scrap rubber tires: 1.5%, 2%, and 5%. This study investigates the degree of compaction, shear strength, settlement behaviour (compressibility), and swelling behaviour of scrap rubber tyres as a soil stabiliser. According to the findings, the optimal amount of scrap rubber tyres as a stabiliser that could improve the properties of clayey soil is 2%.

A comparative techno-economic analysis of combined oil and power production from pyrolysis and co-pyrolysis plants utilizing rice straw and scrap rubber tires

In this study, three pyrolysis and co-pyrolysis plants processing rice straw (RS) and scrap rubber tire (SRT) to produce oil and power (i.e., electricity) at 30 t/hr capacity are simulated using SuperPro Designer software. The objective of the study is to comparatively evaluate the techno-economic performance of hypothetical (co-)pyrolysis plants at commercial scale. The RS production is estimated in 36 districts of Punjab, Pakistan through GIS mapping and the location and capacity of the plants are selected accordingly. The RS plant has the lowest capital and annual operating costs of $53.70 million and $43.70 million, respectively however, it is not economically feasible under current conditions due to its low quantity and quality of the produced oil. The base cases of SRT and co-feed (RS and SRT) plants are found to be viable with capital costs of $66.90 million and $68.30 million, and annual operating costs of $77.20 million and $70.30 million respectively. The co-pyrolysis plant produces the highest oil (main product) yield of 74 kilotons annually and power of 4801 KWe with the lowest unit production cost of $950/tonne. Consequently, the co-pyrolysis plant offers the highest economic performance with $35.55 million of net present value (NPV) estimated at a discount rate of 15% over 20 years of plant life. The payback period (PBT), internal rate of return (IRR) and gross margin (GM) are 5.08 years, 34.67% and 21.35% respectively. Sensitivity analysis suggests that the NPV is sensitive to the oil selling price, feedstock cost, and capital investment for all plants. Moreover, economy of scale analysis quantified the effects of different processing capacities on the economic metrics such as NPV, PBT, capital cost, and operating cost.

Experimental Analysis and Evaluation of the Compressive Strength of Rubberized Concrete During Freeze–Thaw Cycles

Recycling scrap tires provides an alternative source of fine aggregates for the production of rubberized concrete and this will lead to significant increase in concrete frost resistance, environmental protection, and conservation of natural sand and gravel resources. In this paper, a total of 25 groups of rubberized concrete were produced by adding scrap tire rubber particles of different sizes, contents, and pretreatment methods to replace the fine aggregate, and their compressive strength during freeze–thaw cycles was studied from both the macro- and meso-perspectives. The results indicated that the decrease in concrete strength and weight was notably restricted by the presence of rubber particles during freeze–thaw cycles. The rubber fine aggregate with smaller particle sizes enhanced the concrete frost resistance more significantly, and the F100 of concrete with rubber particles of 1.0–2.0 mm increased from 76.6 to 86.5% by increasing the rubber content from 0.0 to 5.6%. The effects of rubber fine aggregate on concrete compressive strength during freeze–thaw cycles were quantified. On this basis, a forecast model for rubberized concrete compressive strength in freeze–thaw cycles was proposed, and the effects of the particle size, content, and pretreatment of the rubber particles were considered. The calculated results agreed well with the test results both in this study and the relevant peer studies, indicating that the model can provide a good reference for the design and engineering application of rubberized concrete in frigid environments.

A study on eco- friendly composite blocks incorporating scrap tyre rubber and steel slag as coarse aggregate with sisal fiber

Global modernization trends result in significant updating of methodologies in constructional activities. This progression makes resources scarce. On the other hand, waste from industry is piling up of late and managing scrap is the principal concern faced globally. In the current scenario, the livelihood environment has noteworthy awareness of waste recycling. Globally, the throwaway problem is the most significant cause of environmental pollution. Recent growth in transportation has generated scrap rubber from automobiles. M30 geopolymer composite blocks incorporating scrap tyre rubber and steel slag as coarse aggregate were investigated. Scrap tyre rubber and steel slag were incrementally added at 0%, 5%, 10%, 15%, and 20% to replace coarse aggregate with sisal fiber for 5% fly ash. In the present work, basic properties were investigated and the mechanical properties of geopolymer composites were determined. It is found that compressive characteristics increased for the addition of 5% scrap tyre rubber with 5% sisal fiber of fly ash, but it declined for other combinations of 10%, 15%, and 20% scrap tyre rubber with 5% sisal fiber. Similarly, compressive characteristics increased for the addition of 5% steel slag with 5% sisal fiber for fly ash but declined for geopolymer composites with 10%, 15%, and 20% steel slag with 5% sisal fiber. The trend of increase is the same for scrap tyre rubber with sisal fiber and steel slag with sisal fiber for flexural characteristics. It reveals that M30 geocomposite blocks with 5% scrap tyre rubber, 5% sisal fiber and steel slag with 5% sisal fiber are optimal. Also, microstructural properties were studied.

Using Waste Tire-Derived Particles to Remove Benzene and n-Hexane by Dynamic and Static Adsorption.

Scrap tire rubber particles were used and evaluated to adsorb some gaseous volatile organic compounds (VOCs), such as benzene and n-hexane. The results present that the adsorption capacities were 0.18 and 0.072 mg/g for n-hexane and benzene, respectively, in the static adsorption mode; the effective adsorption may be attributed to the carbon black of the tire. The adsorption process is in accordance with the Freundlich isothermal model and Lagergren pseudo-first-order kinetic equation. Correspondingly, the adsorption process is multilayer adsorption analyzed by the intramolecular diffusion model. In the dynamic adsorption mode, the maximum adsorption efficiencies of n-hexane and benzene were 80.7 and 81%, respectively, at flow velocities of 0.1 L/min n-hexane and 0.2 L/min benzene.