Recycled Rubber Tyres Research Articles

Construction of Electrically Heated Pavement Using Recycled Waste Rubber Tires

Construction of Electrically Heated Pavement Using Recycled Waste Rubber Tires

Building a Greener Future: Advancing Concrete Production Sustainability and the Thermal Properties of 3D-Printed Mortars

The integration of waste materials in extrudable cement mixtures has the potential to make the construction industry more sustainable by reducing carbon footprints and developing eco-friendly materials. This along with advancements in 3D concrete printing (3DCP) provides engineering and architectural benefits by reducing material waste and costs. In this paper, the impact of waste incorporation on properties of mortar and concrete is examined. The use of waste materials, such as pumice, coal slag, agricultural lignocellulosic residues, and recycled rubber tyres, to improve thermal insulation and durability of cementitious composites is discussed. In addition, the incorporation of air-entraining admixtures with surfactant activity is explored for their indirect effect on thermal behaviour, pore size reduction, and enhancement in concrete properties. This review includes important topics such as a strength resistance to freezing and thawing, fire resistance, plasticising effect, and delay in cement hydration. These findings highlight the benefits of using diverse waste materials in construction, providing a multidimensional approach to waste management, cost optimization, and enhanced construction materials in the context of 3DCP.

Balancing strength and sustainability: Incorporating recycled tyres and pawpaw fibre in polystyrene composites

AbstractThe study presents the development and characterization of rubberized fibrillated polystyrene composites using recycled rubber tires and pawpaw fibres. The composites were prepared by varying the proportions of rubber and fibre. FTIR, SEM, EDX and hardness testing were used to characterize the composites. FTIR spectroscopy revealed distinct peaks, including hydroxyl and amine, but with a notable absence of the O‐H group in nearly all composites, affirming their durability and potential suitability for applications in moist environments. SEM results showed that the introduction of rubber tires did not significantly alter the smooth and fine‐grained nature of the polystyrene resin, whereas the inclusion of pawpaw fibre resulted in an irregular and coarse surface. Mechanical testing demonstrated that the hardness of the composites was dependent on the composition, with rubber‐rich composites being more flexible and pawpaw‐fibre‐rich composites exhibiting greater rigidity.

Optimizing Sustainability of Concrete Structures Using Tire-Derived Aggregates: A Performance Improvement Study

Tire-derived aggregate concrete (TDAC), or rubberized concrete, is gaining ground as an eco-friendly option in civil engineering. By substituting traditional coarse aggregates with recycled rubber tires, TDAC offers a greener choice with excellent energy absorption capabilities. This leads to robust structures and reduced upkeep expenses. Nonetheless, TDAC’s lower strength than regular concrete requires a delicate balance between energy absorption and strength. This study investigates two enhancements to TDAC performance: (a) the impact of sodium hydroxide (NaOH) solution pretreatment and SikaLatex bonding agent addition on TDAC’s compressive strength, and (b) the use of varying water–cement ratios and superplasticizer to enhance TDAC’s mechanical properties. This study involves concrete cylinder compression tests and the creation of strength estimation equations. Results show that NaOH-treated tire-derived aggregate (TDA) boosts workability, increasing slump by 4.45 cm (1.75 in), yet does not significantly enhance compressive strength, causing a 34% reduction. Conversely, combining NaOH pretreatment with Sikalatex bonding agent enhances workability by 28% and boosts compressive strength by 21% at the same water-cement ratio. To optimize performance, it is advised to employ modified TDA concrete with a water–cement ratio under 0.34 and superplasticizer. These findings highlight the potential of modified TDA concrete in sustainable and seismic-resistant designs.

Use of Waste Tires as Transverse Reinforcement and External Confinement in Concrete Columns Subjected to Axial Loads

Approximately 246 million waste tires are generated annually in the United States. That is roughly three tires per four individuals in the country. Most tires end up in landfills, adversely affecting the environment. In the last two decades, researchers have explored using tire chips in concrete to replace a portion of coarse aggregates. Past studies have indicated that up to 50% of coarse aggregates in concrete can be replaced with tire chips. This research proposes using recycled rubber tires and rubber chips in concrete columns. The tires are used as external transverse reinforcement in plain concrete columns. The tires function as formwork during the pour while providing confinement after curing. The concepts in this research can be used for retrofitting structures with inadequate foundations and constructing new structures. After analyzing the data from this research, the axial compressive test of confined columns was 50% greater on average than unconfined columns. The confinement effectiveness ratio for all confined specimens was greater than one.

Silica Aerogel-Rubber Composite: A Sustainable Alternative for Buildings' Thermal Insulation.

Silica aerogel composites with recycled tire rubber have been synthesized and evaluated for their potential use for thermal protection in buildings. The present work describes for the first time the preparation of silica-based aerogel composites containing recycled rubber tires reinforced with polyvinyl butyral (PVB) by hot pressing. The developed composite was extensively characterized regarding its physical, morphological, thermal and mechanical features, and the results showed their properties were relevant, leading to composites with different properties/performances. The obtained bulk density values were satisfactory, down to 474 kg·m−3, and very good thermal properties were achieved, namely, thermal conductivity as low as 55 mW·m−1·K−1 for composites with silica aerogel, recycled tire rubber and PVB. The most promising composites were those based on low bulk density and thermal conductivity values, and they were thermally stable, indicating their suitability for thermal insulation applications.

Thermal conductivity of scrap tire rubber-sand composite as insulating material: Experimental investigation and predictive modeling

Scrap tire rubber of good thermal insulating properties can be reused with soils as a new sustainable construction material. While the heat conduction mechanism of this tire rubber-soil composite has not been fully understood. The present study investigated the thermal behavior of scrap tire rubber-sand composite for using it as an insulating material in thermo-active applications. Several series of thermal conductivity tests were conducted on scrap tire rubber-sand composite prepared with different sand/shredded tire particle size ratios, shredded tire mixing ratios, and degrees of saturation. A predictive model was developed within the framework of normalized thermal conductivity concept that could capture the experimental data. The results showed that addition of shredded tires leads to a considerable reduction in thermal conductivity of sand, indicating great potential of using recycled scrap rubber tires in the construction of insulation layers. With an increase in degree of saturation, the order of thermal conductivity increase was found to be: sand > scrap tire rubber-sand composite > shredded tires. The spatial distribution of solid particles changed from ‘rubber-connected insulation layer’ to ‘sand-encompassed conduction path’ with increasing sand/shreds tire particle size ratio. The normalized thermal conductivity exhibited a linearly increasing trend with shredded tire mixing ratio, and the increase rate mainly depended on degree of saturation and particle size ratio. The predicted thermal conductivity showed satisfactory accuracy for engineering design, as reflected by the absolute percentage difference being controlled under 25%. The validity of the prediction model was also demonstrated based on the experimental results reported in the published literature. Additional research is recommended to assess the effects of particle morphology on thermal conduction of the binary-solid particle system.

Use of recycled tires for earthquake protection of structures

The article presents numerous structures of earthquake-resistant foundations that have
 been developed by the authors and other engineers over the past more than 30 years, in which recycled metal-cord tires are used. The designs of dynamic dampers of dynamic vibrations, in
 which the containers for bulk fillers are made of recycled tires, are presented. Recycled tires are also effectively used in the creation of earthquake shields, as well as reinforcing elements and
 seismic insulation
 layers of earthquake-resistant ground dams. In all the above-mentioned technical solutions, the earthquake resistance of buildings and structures is achieved due to the unique geometric and physico-chemical-mechanical properties of recycled rubber tires with a metal cord.

Physical and Mechanical Properties of Granulated Rubber Mixed with Granular Soils—A Literature Review

End-of-life tires (ELTs) represent a great source of readily available, low-cost and sustainable construction materials having excellent engineering properties. Their reuse (in the form of granulated rubber mixed with soils) in large-volume recycling civil (geotechnical) engineering applications would be beneficial and should be encouraged. It is estimated that at present worldwide only less than 10% of ELTs are reused in geotechnical applications, while nearly 40% are recycled as tire-derived fuel. Although many studies have focused on the material characterization of soil-rubber mixtures (SRMs), it appears that the results of such investigations have not been properly compiled and compared, making it difficult to fully understand the potential applicability of SRMs. In an attempt to provide useful insights facilitating the use of SRMs as geotechnical construction materials, this review paper presents a comprehensive review of published research on the engineering properties of granular soils (i.e., mainly sand and gravel) blended with various recycled rubber inclusions. Available experimental data are scrutinized, and the results of the analyses are presented and discussed primarily in terms of effects of rubber content and aspect ratio (ratio of rubber to gravel median particle sizes) on compaction, permeability, strength and compression properties along with dynamic and cyclic deformation characteristics of SRMs. This review paper may help to alleviate the concerns of designers and consumers and encourage and further promote the use of recycled rubber tires on a larger scale in civil engineering projects.

A DEM method for simulating rubber tyres

Recently, recycled rubber tyres were found to be an economical and environmental-friendly reinforcement material in geotechnical engineering. Although the use of rubber tyre-reinforced soil has become increasingly popular, there is still a lack of a robust and systematic method to model rubber tyres when using the discrete-element method (DEM) to investigate the stress-strain responses. In this paper, DEM rubber tyres are simulated by bonding regular-packed balls, and numerically tested under tensile force using the particle flow code in three dimensions. When comparing the effects of different packings on the sample, using Young's modulus and Poisson's ratio, it was found that only body-centred-cubic packing could achieve a Poisson's ratio of 0·5 representing no volume change during the deformation of rubber. The difference between uniaxial compression and tension simulations was also compared as well as the influences of particle overlapping, particle radius and sample aspect ratio on the mechanical response of the tyre model. Finally, the DEM parameters were set to match the experimental Young's modulus data. This proposed DEM rubber tyre strips model could be a basis to study other rubber reinforcements such as tyre chips and shreds, irregular rubber buffings and granulated rubber.

Numerical Simulation of the Dynamic Response of Ballasted Track Overlying a Tire-Reinforced Capping Layer

This paper describes a 3D finite element (FE) model developed to understand the dynamic response of a ballasted track in which the underlying capping layer is reinforced using recycled rubber tires. Track deflection, the lateral spreading of ballast and vertical stress transmitted from the capping layer to the subgrade are discussed by considering the effect of reinforcement provided by these infilled tires. In this respect, the capping layer is confined and has improved damping properties. The cellular structure of the rubber tire assembly can radially confine the infilled materials, and thus reduce excessive lateral spreading and vertical displacement that would otherwise occur in a conventional track. At the same time the tire and gravel composite layer acts like a stiff but flexible “mattress” that controls the stress transmitted to the underlying subgrade while making it more uniform. Typical soft and stiff subgrade materials were used to investigate the dynamic response of track, and the stress paths of subgrade at different depths have been studied. It is noted that the effect of the tire assembly on the stress distribution within the subgrade decreases with depth, and the tire-reinforced track deflects less than its unreinforced counterpart at any given train speed.

Waste Rubber Tires: A Partial Replacement for Coarse Aggregate in Concrete Floor Tile Production

Concrete tile is one of the most used construction materials in the world. Cement and aggregate, which are the most important constituents used in concrete tile production, they are the vital materials needed for the construction industry. This led to a continuous and increasing demand of natural materials used for their production. Parallel to the need for the utilization of the natural resources emerges a growing concern for protecting the environment and a need to preserve natural resources (such as aggregate) by using alternative materials which are recycled or waste materials. In this research, a study was carried out on the use of used rubber tires as a partial replacement for coarse aggregates in concrete tile production using locally available waste tires. A review of relevant literatures was done to study previous works in the subject matter. The research was carried out by conducting tests on the raw materials to determine their properties and suitability for the experiment. Concrete mix designs are prepared using the DOE method and a total of 12 mixes were prepared consisting of two concrete grades (C25 and C30). The specimens were produced with percentage replacements of the coarse aggregate by 10, 20, 30, 40 and 50% of rubber aggregate with and without supper plasticizer (admixture). Moreover, a control mix with no replacement of the coarse aggregate was produced to make a comparative analysis. The prepared samples consist of concrete cubes, cylinders and beams. Laboratory tests were carried out on the prepared concrete samples. The lists of tests conducted are; material property, slump, unit weight, compressive strength, splitting tensile strength and flexural strength tests. The data collection was mainly based on the tests conducted on the prepared specimens in the laboratory. The test results were compared with the respective conventional concrete properties and show that there is a reduction in compressive strength of the concrete due to the inclusion of rubber aggregates. This is improved by using admixture to some extent, but lower density and enhanced ductility are the same, and there was a slight increase in flexural strength without admixture. The overall results show that it is possible to use recycled rubber tires in concrete tile production as a partial replacement for coarse aggregates. Nevertheless, the percentage of replacement should be limited to 10%.

Applicability study of a low cost seismic isolator prototype using recycled rubber

In order to protect buildings against earthquakes that are categorized as "common" according to the Peruvian Earthquake Resistant Standard, a prototype of Recycled Rubber Seismic Isolator ("RRSI") was developed in the structural laboratory of the Japan-Peru Center for Earthquake Engineering Research and Disaster Mitigation - CISMID, Peru. The raw material used to manufacture this device was recycled rubber tires; the rubber tire was cut into square shape sheets with 190mmx190mm of cross-section and a total thickness of around 11 mm. Rubber tire sheets were joined to each other by a vulcanization process, including rubber layers with 3mm of thickness made of recycled rubber tire powder in between rubber tire sheets; and in between the rubber tire sheet and the steel plate at both ends of the bearing.
 Two specimens were tested in a shaking table under a free vibration impulse or displacement in order to get their natural vibration frequency, natural period, and inherent damping. Then, to obtain the hysteretical behavior, a cyclic lateral reversal-loading test was conducted on three different specimens applying a constant axial load of 330MPa, 270MPa, and 220MPa respectively and a lateral displacement pattern with different levels of shear deformations up to the failure, which occurs at a shear strain of around 100%.
 From the experimental results, a nonlinear hysteretic behavior and energy dissipation were observed, decoupling the lateral movement. Finally, a numerical model was proposed to model the nonlinear hysteretic behavior of the RRSI based on a Modified Bouc-Wen model. This numerical model was simulated by using the specimens as base isolators for buildings.

Partial replacement of coarse aggregate by scrap rubber tire in concrete construction

Concrete is one of the most widely used construction materials in the world. Cement and aggregate, which are the most important constituents used in concrete production, are the vital materials needed for the construction industry. This inevitably led to a continuous and increasing demand of natural materials used for their production. Parallel to the need for the utilization of the natural resources emerges a growing concern for protecting the environment and a need to preserve natural resources (such as aggregate) by using alternative materials which are recycled or waste materials. In this research, a study was carried out on the use of recycled rubber tires as a partial replacement for coarse aggregates in concrete construction using locally available waste tires. In the first part of this thesis, the background of the study and the extent of the problem were discussed. The research was carried out by conducting tests on the raw materials to determine their properties and suitability for the experiment. Concrete mix designs are prepared using the Indian standard method and a total of 9 mixes were prepared consisting of three concrete grades (M15, M25 and M30). The specimens were produced with percentage replacements of the coarse aggregate by 10%, and 25% of rubber aggregate. Moreover, a control mix with no replacement of the coarse aggregate was produced to make a comparative analysis. The prepared samples consist of concrete cubes, cylinders and beams. Laboratory tests were carried out on the prepared concrete samples. The lists of tests conducted are; slump, unit weight, compressive strength, splitting tensile strength, and flexural strength tests. The data collection was mainly based on the tests conducted on the prepared specimens in the laboratory. The test results were compared with the respective conventional concrete properties and show that there replacement should be limited to a specified amount and the application should be restricted to particular cases where the improved properties due to the rubber aggregates are desirable and when the corresponding demerits of the rubber aggregates don't affect the use of the structure.

Effect of Waste Tyre-Rubber Aggregate on the Strength Properties of Concrete

This research studied strength-characteristics of concrete using waste tyre-rubber as partial replacement for coarse aggregate in concrete construction and compares the results to those of conventional concrete. The specimens were produced with percentage replacements of the coarse aggregate by 5%, 10% and 15 % of rubber aggregate. A control mix with no replacement of the coarse aggregate was produced, to make a comparative analysis. The samples consisted of concrete cubes, cylinders and beams. Various tests (such as slump, compressive strength, splitting tensile strength and flexural strength tests), were conducted. Data-collection was mainly based on the results of the tests conducted on the specimens in the laboratory. The results show that there is a reduction in the compressive strength of the concrete, due to the inclusion of rubber aggregates. Compressive strength losses of 12.69%, 17.75% and 25.33% were noticed for 5%, 10%, 15% replacement of coarse aggregate, respectively; tensile strength losses of 13.01%, 20.12%, and 24.76% were observed, respectively, when 5%, 10%, 15% of the coarse aggregate was replaced, after 28 days of curing; -0.1%, -0.15% and 0.2% decrease in flexural strength was observed for 5%, 10% and 15% replacement, respectively, after curing for 28 days. Rubberised concrete was found to have some desirable characteristics (such as lower density, enhanced ductility, and a slight increase in flexural strength in the lower compressive strength concrete categories). The overall results show that it is possible to use recycled rubber tyres in concrete construction, as a partial replacement for coarse aggregates. Nevertheless, the percentage of replacement should be limited to 10% (which ensures the strength of the concrete is kept within the required range), and the application should be restricted to particular cases where the properties related to the replacement with the rubber aggregates clearly indicate an improvement on conventional concrete, and so are desirable.

Hazardous organic chemicals in rubber recycled tire playgrounds and pavers

In this study, the presence of hazardous organic chemicals in surfaces containing recycled rubber tires is investigated. Direct material analyses using solvent extraction, as well as SPME analysis of the vapour phase above the sample, were carried out. Twenty-one rubber mulch samples were collected from nine different playgrounds. In addition, seven commercial samples of recycled rubber pavers were acquired in a local store of a multinational company. All samples were extracted by ultrasound energy, followed by analysis of the extract by GC–MS. The analysis confirmed the presence of a large number of hazardous substances including PAHs, phthalates, antioxidants (e.g. BHT, phenols), benzothiazole and derivatives, among other chemicals. The study evidences the high content of toxic chemicals in these recycled materials. The concentration of PAHs in the commercial pavers was extremely high, reaching values up to 1%. In addition, SPME studies of the vapour phase above the samples confirm the volatilisation of many of those organic compounds. Uses of recycled rubber tires, especially those targeting play areas and other facilities for children, should be a matter of regulatory concern.

Conventional concrete with addition of recycled rubber tires: Study of the mechanical properties

The world is now pressing for decreasing emissions of greenhouse gases, the reduction and possible revocation of culling and disposal of materials resulting from manufacturing processes that pollute and degrade the environment. Among these problems unused tires has become a major problem for the environment due to years of provisions incorrect. On motion of reuse, recycling and waste disposal, construction has become a major partner of the other production areas to reduce several types of industrial wastes by reusing these materials, the introduction of these materials in construction products civil, replacement of traditional materials and various other ways. Have produced different concrete mixtures without and with different percentages of rubber tires. The results indicate a clear loss of strength both in compression as in tension. Key words: alternative materials, materials and components in construction, materials recycling.

Freeze/Thaw Performance of Concrete Using Granulated Rubber Crumb

This paper evaluates the properties and use of recycled rubber tyres in the form of rubber crumb as a freeze/thaw protection agent when used in concrete. Reusing scrap tyres in the form of rubber crumb in concrete could benefit the environment by contributing to the percentage of tyres used for a variety of recycling processes such as carpet underlay or tyre derived fuel, thus reducing disposal of tyres to landfill sites and the chemical usage of air entraining agents as a means of achieving freeze/thaw protection.Concrete cubes of 100mm were produced from design mixes which have been classified as plain, air entrained and rubber crumb and subjected to freeze/thaw cycles at 5 days of age.Thawing was conducted in water to ensure full saturation of pores and maximum stress on the concrete samples. The rubber crumb and plain concrete mixes were compared against the freeze/thaw performance of that entrained with air. Air entrainment is known to protect against freeze/thaw action.Rubber crumb when used at a 0.5% addition by volume provided the optimum freeze/thaw protection whilst maintaining the maximum compressive strength. The research shows that rubber crumb was effective at providing freeze/ thaw protection albeit with a reduced compressive strength when compared to air entrained concrete. The practical constraints of the test program were time and freezer space so the test was limited to 50 freeze/thaw cycles, which was sufficient for conclusions to be drawn.This paper contributes to the understanding of the effects of varying doses of rubber crumb in concrete when used as a freeze/thaw protection additive. The final compressive strength of the concrete mixes tested at freeze/thaw and non freeze/ thaw conditions are determined. The compaction of concrete is raised as an area of concern with regard to rubber particle separation within the plastic phase of the concrete's life.

Use of Recycled Rubber Tires in Normal and High-Strength Concretes

This paper reports an investigation on the use of recycled rubber tires in producing normal- and high-strength concretes under tropical conditions, as experienced in Singapore and the Asia region. The tests performed on fresh concrete were a slump test and a determination of unit weight and air content. Tests on hardened concrete were nondestructive tests that included measurements of hardened density and ultrasonic pulse velocity; and destructive tests that covered a cube test to obtain the compressive strength of concrete, and an axial compression test on concrete cylinders to determine their stress-strain curves. The effects of water-cement ratio (w/c), rubber as aggregate replacement, rubber type, mineral admixture as cement replacement, steel fiber reinforcement, and curing age on the properties of rubberized concrete were assessed and compared. Recommendations were given on the applications of normal- and high-strength concretes containing recycled rubber in relation to their fresh and hardened properties.

Fire retardancy and environmental assessment of rubbery blends of recycled polymers

Flame retarded thermoplastic polymer compounds were prepared containing recycled rubber tyres, low density polyethylene, ethylene vinyl acetate copolymer and an intumescent additive system consisting of waste polyurethane foam and ammonium polyphosphate. The effect of the additives on the combustion properties was characterised by Limiting Oxygen Index, UL 94 and mass loss calorimetric measurements. The environmental impact was estimated by determining the gas components of CO2 and CO evolving from the compounds during the burning process using a gas analyser system constructed by coupling an FTIR unit to a mass loss calorimeter. The new material forms a thermoplastic rubber of excel- lent processability making it suitable for application in construction industry.