Waste Rubber Research Articles

Effects of basalt fibre and rubber particles on the mechanical properties and impact resistance of concrete

The application of waste rubber particles and basalt fibre (BF) in concrete can not only improve the performance of the resulting concrete but also alleviate the environmental pressures related to waste tire disposal. In this study, the impacts of rubber particles and BF on the mechanical and impact performance of concrete are experimentally investigated. Additionally, the macroscopic test phenomenon is explained based on the appearance of the microstructure. The results show that for basalt fibre-reinforced concrete (BFC), when the BF content increases from 0 to 0.4 %, the cube compressive strength and elastic modulus decrease from 71.5 MPa to 62.5 MPa and 44.5 GPa to 41.0 GPa, respectively, while the bending strength increases from 5.9 MPa to 6.6 MPa and then decreases to 6.3 MPa. A BF content of 0.3 % is selected to prepare basalt fibre-reinforced rubber concrete (BFRC). As the rubber particle content of BFRC increases from 0 to 20 %, the cube compressive strength, elastic modulus and bending strength decrease from 64.3 MPa to 51.5 MPa, 41.9 GPa to 33.5 GPa and 6.6 MPa to 5.9 MPa, respectively. However, the reduction rate of the mechanical properties of BFRC is approximately half that of fibre-free rubber concrete at the same rubber content. The shapes of the stressstrain curves of the BFC and normal concrete (NC) are similar, whereas the descending stage of the stressstrain curve of the BFRC is obviously gentler, and the whole BFRC stressstrain curve is much fuller, reflecting typical ductile failure. Both the BF and rubber particles contribute to impact performance improvement, but the effect of the rubber particles is much greater than that of the BF. Compared with that of the NC, the incorporation of 0.3 % BF increases the initial crack impact energy (W1) and final crack impact energy (W2) by 71 % and 79 %, respectively, but when 20 % rubber particles are additionally added, the increase rates of W1 and W2 reach 668 % and 686 %, respectively. The impact life evolutions of BFC and BFRC can be described effectively by a two-parameter Weibull distribution function.

Experimental study of the effect of the temperature of inert gases on the intensity of thermal decomposition of rubber

THE PURPOSE. An experimental method is used to evaluate the effect of the temperature of inert gases on the rate of thermal decomposition of waste rubber products (fragments of a car tire) upon their direct contact.METHODS. The research was carried out on a test firing stand at a stationary mode of gas movement in the temperature range from 300 °C to 500 °C. The initial weight of the rubber was 4 grams. The thermal decomposition of rubber was carried out due to the thermal energy of inert gas released during the combustion of a propanebutane mixture with air at α = 1.1...1.15. The consumption of fuel and oxidizer remained constant, the change in gas temperature was carried out by heat exchange of hot gases and water in the heat exchanger.RESULTS. Metodology of conducting experiments, the object of research under the study, results of the research and their analysis are described in the article. The main parameters were selected: the rate of decrease in rubber mass depending on the temperature of the gases, the limiting value of the gas temperature at which sulfur in solid form remains in the decomposed part of the rubber.CONCLUSION. It was found that with increasing temperature of the inert gas, the rate of thermal decomposition of rubber increases. When rubber is in a gaseous environment in the temperature range from 450 0C to 500 0C, the sulfur content in the solid residue remains practically unchanged. The average rate of pyrolysis was 0.02 kg/h, which is 6 times higher than the rate of pyrolysis in the retort (0.003 kg/h).

Utilization of Silica Fume and Sodium Hydroxide in Treated Crumb Rubber for Cement Mortar

Cement mortar offers an excellent replacement for materials such as fine aggregate with tire rubber waste in the form of crumbs. It provides excellent environmental and technical benefits to concrete production using recycled materials. As such, it contributes to the sustainable development of the construction industry. This paper mainly emphasizes the strength of untreated and treated crumb rubber from waste tires in cement mortar. Crumb rubber that has been pre-treated with Silica fume (SF) and sodium hydroxide (NaOH) to improve the strength of the mortar mix. This research used a cement-aggregate mix ratio of 1:4 and a water-cement ratio of 1:2. Five different percentages of fine aggregate replacement (0, 3, 6, 9, and 12%) was selected. The compressive strength, density, and water absorption of the mortar were measured at 28 days to find optimum strength. The compressive strength of the cement mortar mixed with treated crumb rubber showed significantly higher values, with an increase of 92% for 12% treated crumb rubber by sodium hydroxide (TN12) compared to untreated crumb rubber. The density value of the mortar cube mixed with treated crumb rubber decreased when the percentage of replacement for treated crumb rubber increased. In the application of roof tiles, lower density values provide an advantage for workability during installation. For water absorption, the treated crumb rubber contributes to a lower percentage of water absorption (acceptable until 6% for SF and 9% for NaOH) compared to the control sample as untreated crumb rubber. Therefore, a mixture of mortar with treated crumb rubber, especially NaOH solution, is better than the untreated crumb rubber specimen.

Some Properties of a Cementitious Mortar Containing Granulated Rubber Waste and Brick Fillers: An Experimental Study, Mathematical Modeling and Optimization

Abstract The objective of this study is to assess the impact of incorporating rubber tire waste and brick fillers as a substitute for sand in cement mortar samples. The evaluation includes measurements of the bending strength, dynamic modulus of elasticity, and displacement. The replacement of sand by rubber waste (RW) and brick waste (BW) at 0%, 10%, 20% and 30% for rubber waste and 0%, 2.5%, 5.0%, 7.5%, and 10% for brick waste by volume was experimentally conducted. According to the findings, the introduction of rubber waste leads to a significant reduction in the flexural strength, dynamic modulus of elasticity, and displacement. The brick waste can be considered a suitable filler, which minimizes the negative effect of rubber tires and tends to result in suitable mixtures. The optimal values (10.10% for the RW and 10% for the BW) showed good agreement with the experimental results, with differences of 1.85%, -4.73%, and -4.48% for the displacement, flexural strength, and dynamic elastic modulus, respectively.

Comprehensive Review on Utilization of Construction Demolished Waste and Crumb Rubber for Sustainable Pavement Construction

Comprehensive Review on Utilization of Construction Demolished Waste and Crumb Rubber for Sustainable Pavement Construction

Structural, radiation shielding, thermal and dynamic mechanical analysis for waste rubber/EPDM rubber composite loaded with Fe2O3 for green environment

Increasing waste rubber recycling produces a specious range of products for many valuable applications. Waste Rubber/EPDM composite with different concentrations was prepared. Infrared spectroscopy (FTIR) is used to identify the chemical composition. A water absorption test, Dynamic mechanical analysis (DMA), and Thermal Gravimetric Analysis (TGA) were performed. The (75/25) WR/EPDM rubber composite exhibited the best behavior with the highest mechanical performance. Fe2O3 was added to (75/25) WR/EPDM rubber composite. Water absorption, FTIR, TGA, and DMA were investigated. The composite performance was improved with increasing Fe2O3 content. The linear attenuation coefficients (μ) were also measured as a function of the concentrations of Fe2O3 for γ-ray energy 662 keV by using 137Cs point source; the radiation shielding can be denoted by numbers of parameters like mass attenuation coefficient (μm), half value layer (HVL), Tenth value layer TVL and radiation protection efficiency (RPE%), radiation protection efficiency increased as Fe2O3 increased.

Turning Waste into Wealth: A Conceptual Design of Limonene Production Plant from Waste Rubber Tyre

Limonene production represents a compelling opportunity in the global market, given its competitive landscape dominated by a few key players who control nearly half of the industrial-grade limonene market. Due to the high polyisoprene content in vehicle tyres, along with the rising number of waste rubber tyres, the production of limonene by pyrolysis of tyres may represent a future trend to turn waste into wealth. Hence, a conceptual plant design was carried out to determine the feasibility of limonene production from waste rubber tyres in Malaysia. This feasibility study involved Aspen Plus simulation and illustrated the main processes using Process Flow Diagram (PFD), Piping and Instrumentation Diagram (P&ID), and comprehensive stream table integrating material and energy balances. The desired product, which is limonene, was produced by the gas-solid pyrolysis within a conical spouted bed reactor (CSBR) in an inert atmosphere of non-oxidizing, achieving limonene of 98% purity. Besides, process optimization via pinch analysis has been performed to recover 223.84 kWh of energy using heat integration, resulting in 62.06% of energy saving. From the economic analysis conducted, the total capital investment is RM12.9 million and the annual revenue is RM124.7 million with an annual limonene production of 543.1 tons. The financial analysis demonstrated a robust return on investment (ROI) of 303%, a simple payback period of 0.33 years and ta Net Present Value (NPV) of RM 432.2 million.

Thermal decomposition kinetics and aging lifetime prediction of waste rubbers in porous elastic road surface

The waste rubbers used as partly aggregates in porous elastic road surface (PERS) mixture are more easily to be attacked by the heat and oxygen during the service process. This study aims to investigate the thermal decomposition kinetics of waste rubbers in PERS and propose a method to predict the lifetime of waste rubbers. Firstly, the PERS mixtures containing unaged and aged waste rubbers were prepared with void ratio of 25 % and rubber particle content of 25 %. Then, from the water residual results, it can be seen that the residual stability and freezing-thawing splitting strength ratio of PERS mixtures containing waste rubbers being aged for 7 days significantly decreased to 65 % and 59 % compared with that of the unaged PERS mixture, which cannot be used as pavement. The thermal decomposition kinetics of waste rubbers fixed with the first-order reaction, which was related with the road performance of PERS mixtures by the mass loss rate of 17 % after being aged for 7 days. Based on that, the lifetime prediction equation of waste rubbers was established. It is expected that this work provides a new strategy for predicting the lifetime of waster rubbers in PERS pavement during the service process.

Development in the Study of Mechanical Prop-erties and Damage Constitutive Models of Rub-ber-Reclaimed Concrete

Advances in rubber-reinforced concrete technology and its applications in engineering are cru-cial for the thorough recycling and safe disposal of waste tire rubber and construction debris. Rubber-reinforced concrete (RAC) is a concrete material produced by substituting some fine and coarse aggregates with waste rubber particles and recycled aggregates. The incorporation of waste rubber particles endows RAC with distinctive mechanical properties and a distinct damage constitutive model. The mechanical properties of rubber recycled concrete mainly in-clude compressive strength, tensile strength, flexural strength, and elastic modulus. Compared to traditional concrete, RAC exhibits slightly lower compressive and flexural strengths but sig-nificantly enhanced tensile strength. This is due to the changes in mechanical properties caused by the softness and elastic properties of rubber particles. In addition, the addition of rubber particles can also improve the energy absorption capacity and impact resistance of concrete. On the other hand, in order to describe the damage behavior of rubber recycled con-crete, some constitutive models were studied. Common models include linear elastic model, plastic model, and damage model. The linear elastic model is suitable for describing the be-havior of rubber recycled concrete during the elastic stage; The plastic model is suitable for describing its deformation behavior during the plastic stage; The damage model can better describe the fracture and failure behavior of rubber recycled concrete, including shear damage, tensile damage, and compression damage. Tailored to the unique characteristics of RAC, these models consider the stiffness of rubber particles and the deformation characteristics of the binding materials, enabling accurate predictions of the stress-strain behavior of RAC. In conclusion, rubber-reinforced concrete possesses excellent mechanical and durability proper-ties, which can be accurately described and predicted using appropriate constitutive models. These findings are crucial for advancing the application and development of rubber-reinforced concrete.

Bond behavior of deformed rebar in concrete containing recycled brick aggregate and waste rubber

The reuse of aggregates and crumb rubber (CR) in concrete is gaining interest globally for reducing the adverse effects on the environment and maintaining construction sustainability. The bond strength of reinforcing rebars in such concrete is one of the key issues to be addressed before their practical application, particularly in structural elements. Pull-out tests were performed on 80 specimens to assess the bond performance of deformed rebars in rubberized recycled brick aggregate concrete (RRBAC). After investigating the strength properties of RRBAC, pull-out tests were performed on two sizes of cylindrical specimens. RBA%, CR%, rebar diameter (d), embedment length (le), and concrete cover-to-rebar diameter ratio (c/d) were among the test variables in this bond behavior investigation. Bond stress-slip relationships were obtained, examined, and average bond strengths were compared with the available codes. Concrete split failure was observed in 79% of the tested specimens, whereas rebar fracture was not seen in any of the tests. The bond strength was found to be decreased with the inclusion of RBAs and CRs though relative improvement was observed for higher percentage RBAs. Additionally, regression analysis was performed on the experimental data to produce a closed-form equation for forecasting the bond strength for RRBAC. With a strong coefficient of determination (R2 = 0.97) and low values of error terms, the predicted bond strengths were seen to be a good agreement with the test results.

Enhancing clayey soil performance with lime and waste rubber tyre powder: Mechanical, microstructural, and statistical analysis

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly.

Multiscale enhancement mechanism of low-temperature performance for degraded recycled waste rubber asphalt binders: MD simulation and microscopic investigation

Desulfurization and degradation are important processes to facilitate the storage of waste rubber asphalt and improve its utilization. However, this process is extremely complex and the mechanisms underlying the resulting performance enhancement remain unclear. This study aims to investigate the multiscale mechanism of rubber degradation and its impact on the low-temperature performance of degraded rubber modified asphalt (DRMA) binder through differential scanning calorimetry (DSC), bending beam rheometer (BBR), fluorescence microscopy (FM) and Fourier transform infrared spectroscopy (FTIR) tests and molecular dynamics (MD) simulations. The results showed that as the degradation of rubber powder deepens, lightweight components decomposed from the rubber are more easily dissolved into the virgin asphalt, thus improving its dispersion. In addition, the small molecular structure after rubber degradation penetrates and fills the aggregation space between asphalt molecules, effectively increasing the molecular activity of asphalt, thus enhancing the low-temperature performance of asphalt.

Effect of multi-walled carbon nanotubes reinforcement on self-healing performance of natural rubber

Abstract This work is motivated by the desire to restore the quality of rubber-based product properties with the intention of prolonging the service life period, thus helping create a sustainable environment by proposing effective rubber waste management. This study experimentally investigated an intrinsically self-healing zinc thiolate grafted natural rubber (NRZT) compound filled with multi-walled carbon nanotubes (MWCNT) to assess its influence on mechanical properties and self-healing performance. The MWCNT loading varied to 0, 2, 4, 6, and 8 phr. The Equilibrium swelling test was used to quantify the amount of ionic and covalent crosslinks formed. Fourier Transform Infrared (FTIR) spectra were used to detect the presence of MWCNT in the compound. The mechanical properties computed by the tensile and tear strength tests showed that the incorporation of MWCNT increased both properties up to three and twofold, respectively. However, as expected, the elongation at break (Eb) value was reduced. The unfilled sample showed that it can heal up to ∼98 %, measured from the tensile strength. However, the healing efficiency obtained from tensile strength reduces to ∼88 % by incorporating 2 phr MWCNT. The Eb and its self-healing efficiency gradually decreased as the MWCNT amount increased. All samples showed outstanding properties under the tearing mode, where the healed samples produced higher tear strength (>100 % healing) than the initial value. Scanning Electron Microscopy (SEM) micrographs revealed a noticeable gap along the healed cut line with increased MWCNT numbers, possibly due to the lower reaction between polymerized zinc thiolate (PZTh) radicals with zinc thiolate (ZT) and rubber molecules. The work aims to investigate the influence of MWCNTs on the mechanical and healing performance of self-healing NR composites by comparing them to their unfilled sample.

Dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) under low-velocity impact: Effect of waste rubber incorporation and low temperatures

This study aims to explore the dynamic response of ultra-high performance engineered cementitious composites (UHP-ECC) incorporating waste crumb rubber (CR) at various temperatures, focusing on its potential to enhance the resilience and sustainability of civil infrastructures against low-velocity impacts. To date, the impact behaviour of UHP-ECC under low temperatures has rarely been explored. Firstly, natural river sand and waste tyre CR was utilized to prepare the UHP-ECC. Then, a series of mechanical tests, including compression test, flexural test and uniaxial tensile test were carried out to investigate the static mechanical properties of rubberised UHP-ECCs. In addition, the effects of different waste CR incorporations (0%, 5%, 10%, and 15%) and various temperatures (25 °C, −5 °C, −30 °C, −50 °C, −100 °C and −196 °C) were comprehensively investigated by low-velocity impact tests with constant impact energy. Lastly, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) model was introduced to evaluate the overall performance of UHP-ECC. It was found that the use of river sand and CR significantly enhanced the tensile ductility and impact toughness of UHP-ECC. Impact energy primarily dissipates through damage such as matrix crack initiation, propagation, and fibre pull-out/rupture within the specimen. Adding CR notably decreased stress fluctuations during impact at room temperature, facilitating steady state energy absorption. Moreover, the time to reach peak impact force decreased with decreasing temperature across all UHP-ECC groups. At room temperature during impact process, fibre failure mode is dominated by pull-out failure, while lower temperatures lead to increased fibre rupture at the cracking surface. In low-temperature conditions, the impact response of rubberised UHP-ECC necessitates a comprehensive consideration of the synergistic effects, including material contraction, fibre bridging capacity, rubber phase transition, and water freezing.

Application of Waste Tire in Construction: A Road towards Sustainability and Circular Economy

The global demand for rubber is on a steady rise, which is driven by the increasing production of automobiles and the growing need for industrial, medical, and household products. This surge in demand has led to a significant increase in rubber waste, posing a major global environmental challenge. End-of-life tire (ELT) is a primary source of rubber waste, having significant environmental hazards due to its massive stockpiles. While landfilling is a low-cost and easy-to-implement solution, it is now largely prohibited due to environmental concerns. Recently, ELT rubber waste has received considerable attention for its potential applications in civil engineering and construction. These applications not only enhance sustainability but also foster a circular economy between ELT rubber waste with the civil engineering and construction sectors. This review article presents a general overview of the recent research progress and challenges in the civil engineering applications of ELT rubber waste. It also discusses commercially available recycled rubber-based construction materials, their properties, testing standards, and certification. To the best of the authors’ knowledge, this is the first time such a discussion on commercial products has been presented, especially for civil engineering applications.

Investigation on storage stability, H2S emission and rheological properties of modified asphalt with different pretreated waste rubber powder

The use of waste rubber powder (WRP) to produce WRP modified asphalt (WRMA) has been proved to have wide application prospects, however, WRMA has poor storage stability and is prone to release H2S and other toxic fumes. Therefore, the one-step method to ameliorate these two problems through pretreating WRP was proposed, and the microwave activation, waste cooking oil (WCO) swelling and acid or alkali solution soaking were applied to pretreat WRP in this study, respectively. The scanning electron microscope and infrared spectroscopy were selected to analyze the microstructures and functional groups of different pretreated WRP. The fluorescence microscopy and hot tube test were employed to evaluate the compatibility of pretreated WRP with asphalt. The H2S gas detector and gas chromatography-mass spectrometry were introduced to research the flue gas emissions of pretreated WRP and prepared WRMA. The experimental results show that the microstructure and functional groups of the pretreated WRP are greatly changed and its surface activity is increased. The storage stability of WRMA prepared with pretreated WRP is obviously improved, and the optimized result is obtained with the microwave/WCO composite treatment, with a segregation index reduction of 40.91%. Also, the pretreatment of WRP does reduce H2S and flue gas emissions. The cumulative H2S concentration reduction of WRP after NaOH solution soaked reaches 32.14% at 30 min, and the total flue gas concentration reduction of the prepared WRMA reaches 21.54%. The results could offer guidance for the clean utilization of WRP, the efficient storage of WRMA and the effective suppression of its flue gas.

Analysis of potential incorporation of waste into asphalt pavements

The incorporation of waste materials into asphalt pavements has gained increasing attention as a sustainable and environmentally responsible approach to road construction and maintenance. This study examines the performance of asphalt mixtures incorporating foliated quartzite waste and rubber asphalt for road pavements. Despite deviations in certain parameters from recommended standards, such as sand equivalent and Los Angeles abrasion, alternative materials like quartzite waste can still be viable for asphalt mixtures if they ensure structural integrity. Mechanical tests reveal that the asphalt rubber and quartzite waste mixture exhibit superior tensile strength and resilience modulus compared to reference mixtures, suggesting enhanced load-bearing capacity and resistance to deformation. This study underscores the versatility of utilizing materials like quartzite waste and rubber from scrap tires in road pavement applications, advocating for further exploration of their suitability, particularly in regions with extensive road networks and diverse environmental conditions. Furthermore, the adoption of these materials promotes environmental sustainability by mitigating environmental damage and reducing the consumption of conventional aggregates in pavement construction, thereby fostering a more sustainable approach to infrastructure development.

Techno- Enviro Benefits of Using Carbon Black and Steel Fibers from Waste Rubber Tyres in Ultra High - Performance Concrete

Techno- Enviro Benefits of Using Carbon Black and Steel Fibers from Waste Rubber Tyres in Ultra High - Performance Concrete

Mechanical Properties of Modified Metakaolin-Based Geopolymer Concrete Containing Tires Rubber Waste and Reinforced with Recycled Steel Fibers

Mechanical Properties of Modified Metakaolin-Based Geopolymer Concrete Containing Tires Rubber Waste and Reinforced with Recycled Steel Fibers

The Effect of Different Proportions of Waste Rubber Substitution on Alkali-Silica Reaction and Mechanical Properties in Mortars

This study investigates the alkali-silica reaction (ASR) and mechanical properties of mortars containing crumb and powder rubber instead of river sand. In this regard, mortars were produced using waste rubber whose ratios in the mixture are 0%, 3%, 6%, 9%, 12%, 15%, 18%, and 21%. ASR expansion, compressive and flexural strength tests were conducted on the samples. ASR measurements were performed on days 3, 7, 14, 21, and 28. Besides, at the end of the ASR experiment, the microstructures of the mortars were examined using scanning electron microscope (SEM) images. Examining the results of this study reveals that the use of waste rubber in rising portions in the mortars led to an increase in the ASR expansions of the mortars. The study shows that the ASR expansions of the mortar samples that have 9% and 15% waste rubber replacement are comparatively higher than the other mortar samples. Furthermore, the results of the SEM analysis verified this finding. The study demonstrates that 3% of waste rubber mortar samples have the highest compressive and flexural strengths. On the other side, the ASR expansion of the mortars with 3% substituted waste rubber was considerably low compared to other mortars containing waste rubber. These findings (ASR, compressive and flexural strength tests results) show that using 3% waste rubber is ideal for producing mortars and supports a sustainable production approach in the sector.