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Organic molecular solids can exhibit rich phase diagrams. In addition to structurally unique phases, translational and rotational degrees of freedom can melt at different state points, giving rise to partially disordered solid phases. The structural and dynamic disorder in these materials can have a significant impact on the physical properties of the organic solid, necessitating a thorough understanding of disorder at the atomic scale. When these disordered phases form at low temperatures, especially in crystals with light nuclei, the prediction of material properties can be complicated by the importance of nuclear quantum effects. As an example, we investigate nuclear quantum effects on the structure and dynamics of the orientationally disordered, translationally ordered plastic phase of the acetylene:ammonia (1:1) co-crystal that is expected to exist on the surface of Saturn's moon Titan. Titan's low surface temperature (∼90 K) suggests that the quantum mechanical behavior of nuclei may be important in this and other molecular solids in these environments. By using neural network potentials combined with ring polymer molecular dynamics simulations, we show that nuclear quantum effects increase orientational disorder and rotational dynamics within the acetylene:ammonia (1:1) co-crystal by weakening hydrogen bonds. Our results suggest that nuclear quantum effects are important to accurately model molecular solids and their physical properties in low-temperature environments. [ABSTRACT FROM AUTHOR]

Clayey soils present challenges in engineering applications due to their inherent properties, such as low shear strength, which usually limits their use in engineering applications. Stabilization of clayey soils is crucial to enhance their performance and suitability for various purposes. Utilizing waste materials like discarded tyres and tile powder as soil stabilizers presents a sustainable solution to mitigate environmental concerns while enhancing soil properties. While previous studies have explored using either crumbled rubber or tile powder independently for soil improvement, their combined effect remained largely unexplored. This study addresses this gap by investigating the synergistic potential of blending crumbled rubber and tile powder to enhance the strength and ductility of clayey soils. A series of laboratory tests were conducted to investigate the combined effect of crumbled rubber and tile powder. First, varying percentages of crumbled rubber (2.5%, 5.0%, 7.5%, and 10%) were mixed with the soil, and standard proctor tests, California bearing ratio (CBR) tests, and unconfined compressive strength (UCS) tests were performed. Results showed optimal performance at 5.0% crumbled rubber, exhibiting the highest values for maximum dry density, CBR, and UCS. Subsequently, different percentages of tile powder (5%, 10%, 15%, and 20%) were added to the soil-rubber mixture (with 5% crumbled rubber). The addition of 15% tile powder to the 5% crumbled rubber mixture yielded the most significant improvements as maximum dry density (MDD) increased from 1.842 g/cm3 (raw soil) to 1.963 g/cm3, UCS increased from 0.5176 kg/cm2 (raw soil) to 2.606 kg/cm2, and CBR increased from 1.757% (raw soil) to 7.84%. The addition of crumbled rubber was found to shift the failure behaviour of the clayey soil from brittle to more ductile, indicating an enhanced ability to undergo deformation before failure. This study's findings highlight the potential of combining crumbled rubber and tile powder as a sustainable solution for enhancing clayey soil properties, paving the way for further research into optimized mixture designs and expanded applications in geotechnical engineering. [ABSTRACT FROM AUTHOR]

High-Content Crumb Rubber Asphalt (HCRA) binder improves road performance and address waste tyre pollution, yet its ageing behaviour is not fully understood. In this study, 70# neat asphalt binder and HCRA with rubber contents of 35% and 50% were selected and aged through the Thin Film Oven Test (TFOT) and Pressure Ageing Vessel (PAV) tests. FTIR (Fourier Transform Infrared Spectroscopy) and DSR (Dynamic Shear Rheometer) were employed to investigate their chemical composition and rheological properties. The FTIR results show that HCRA's chemical test results are similar to those of 70#, but HCRA is more susceptible to ageing. I(C=C) strength decreases with age. The DSR results show that HCRA outperforms 70# neat asphalt binder in terms of viscoelasticity, high temperature performance and fatigue resistance, and exhibits greater resistance to ageing. The ageing index (AI) was obtained through a calculation using the formula, and overall, 70# neat asphalt binder is more sensitive to ageing behaviour and less resistant to ageing, and HCRA is particularly outstanding for fatigue resistance. A strong correlation is observed between chemical composition and some rheological property indicators. Therefore, we are able to predict the rheological properties using chemical composition indicators. This study provides insight into the ageing behaviour of a neat asphalt binder and an HCRA binder and demonstrates that the HCRA binder outperforms conventional asphalt in several performance areas. It also provides theoretical support for the consumption of waste tyres to prepare high content crumb rubber asphalt. [ABSTRACT FROM AUTHOR]

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance. [ABSTRACT FROM AUTHOR]

Year by year, more and more plastic is used worldwide. A large part of post-consumer waste is still stored in landfills instead of being reused. The solution to this problem may be recycled materials (recyclates) or biodegradable materials. The method of 3D printing, regarded as a clean processing technology, can significantly contribute to addressing global plastic pollution by utilizing post-consumer recycled polymers to create new components and parts. Therefore, this study focuses on the assessment of various properties and characteristics of 3D-printed compositions based on post-consumer polypropylene (PP) and rubber crumbs, recycled from packages foils and car tires, respectively. Moreover, within this study, we compared the mechanical performance of the injection molding material with the one obtained from 3D printing. A characterization was made considering the thermal and mechanical properties as well as the "print quality" through the microscopic and tomographic analysis of subsequent print passes, the number of free spaces, and imperfections in the polymer melt. Samples obtained using the FDM and injection methods exhibited comparable melting temperatures, while the samples obtained by injection molding exhibited slightly better mechanical performance, higher hardness, and impact strength. [ABSTRACT FROM AUTHOR]

To address the environmental impact of greenhouse gases in cement production, incorporating cement substitute materials is crucial. However, the slow degradation of discarded tires poses environmental challenges, making burial or incineration unsustainable. This study explores the integration of discarded tires as crumb rubber in concrete and the use of silica fume as a cement substitute. Experimental methods, coupled with neurofuzzy systems, were employed to predict the mechanical properties of the resulting modified concretes. In the experimental approach, silica fume replaced cement at weight percentages of 0%, 10%, 12%, and 15%, while crumb rubber substituted sand at volume percentages of 0%, 10%, and 25%. Compressive and flexural strengths were evaluated at seven, 28, and 90 days, with tensile strength assessed at 28 days. The neurofuzzy system utilized six inputs—cement, gravel, sand, silica fume, water–cement ratio, and sample age—to forecast tensile and compressive strength in silica fume-containing concrete. Similarly, six inputs—cement, gravel, sand, crumb rubber, water–cement ratio, and sample age—were used to predict flexural and compressive strength in rubber-containing concrete. The findings reveal that the inclusion of silica fume enhances the mechanical properties of concrete, while the introduction of crumb rubber diminishes these properties. Specifically, a quantitative analysis demonstrates the positive impact of silica fume on the strength and contrasting effect of crumb rubber. The neurofuzzy system exhibits remarkable accuracy in predicting tensile and compressive strength for silica fume-containing concrete and flexural and compressive strength for rubber-containing concrete. [ABSTRACT FROM AUTHOR]

This research study evaluates the impact of low-density polyethylene (LDPE) modified asphalt binder on the mechanical performance and economical feasibility of asphalt concrete (AC) mixtures. LDPE-modified mixtures were compared with conventional mixes prepared with various binders commonly used in India, i.e., VG 30, VG 40, Polymer-Modified Binder (PMB), and Crumb Rubber Modified Binder (CRMB). LDPE-modified mixtures exhibit superior mechanical performance, increasing the stiffness of AC mixtures by 171% and 125% at 25 °C and 35 °C, respectively, compared to VG 30 base binder. Additionally, the indirect tensile strength (ITS) improved by 51% over VG 30. LDPE-modified mixtures also showed improved resistance to permanent deformation, with RTIndex values up to 133.46% higher than VG 30, and higher fatigue resistance, as indicated by increased CTIndex values compared to VG 30 and CRMB. However, the CTIndex values for LDPE-modified mixtures were 26.32% and 56% lower than those for VG 40 and PMB, respectively. Pavement analysis using 3D-Move showed lesser deflections at pavement layer interfaces, resulting in higher rutting and fatigue life for LDPE-modified pavements. Furthermore, LDPE-modified pavements showed up to 57% higher fatigue life (Nf) and up to 42.33% higher rutting life (Nr) than other pavements. The economic analysis showed that the cost of LDPE-modified pavements is comparable to VG 40 and around 10% more economical than pavements containing PMB. Using LDPE also offers environmental benefits by repurposing up to 750 kg for every kilometer of single-lane pavement section having 50mm thick surface course. Overall, LDPE-modified asphalt mixtures present a sustainable and high-performance solution for asphalt pavement construction. [ABSTRACT FROM AUTHOR]

The issue of forming a reliable and stable structure of a crumb-rubber-modified binder is an important scientific and technical task. The authors supplemented existing concepts of the mechanism of effective interaction with rubber crumb by introducing a preliminary first stage: controlled partial physical destruction of rubber crumb—producing rubber reclaim. Proposed physical methods of rubber crumb destruction include high shear force (roll mills), high temperature, and a plasticizing medium. The controllability and degree of devulcanization of rubber were determined by acetone-chloroform extraction in different time intervals. The degree of devulcanization of rubber in the rubber reclaim was found to be 22 ± 0.24%, with stability over 14 days. It was found that the size of the particles of the rubber reclaim in the bitumen is less than 2 µm. The properties of the structure of the binder modified with rubber reclaim, characterizing the stability and sustainability, have been studied and established. The developed modified binders are stable in storage. Rheological parameters of the structure characterizing intermolecular interaction, such as shear stability for original and RTFOT-aged, modified bitumen, meet requirements of the state standard at test temperature 64 °C. The elastic structural component of the crumb-rubber-modified binder, as indicated by the relative irreversible deformation parameter J3,2, does not exceed 2.6 kPa (<4.5 kPa) at 64 °C. Additionally, it was determined that the rheological structural parameter for fatigue resistance, which characterizes the durability of road pavement under intensive operational conditions, does not exceed 4699 kPa (<5000 kPa) at 16 °C. The use of 10% rubber reclaim combined with waste frying oil provided the opportunity to obtain a modified binder with a stable and sustainable structure without the introduction of additional stabilizers and agents. Test results showed that the overall performance characteristics of the modified binder meet the 64(S)-40 grade standards. [ABSTRACT FROM AUTHOR]

Crumb rubber-modified asphalt mixtures have been proven to have extensive utilization value in road engineering. However, the rubber releases more fumes during the construction period, which causes severe harm to human health and the environment. This research focused on the emission risk of asphalt fume from crumb rubber-modified asphalt, and then the inhibition technology was also optimized. Firstly, the emission behavior and the hazardous evaluation of the asphalt fume from crumb rubber-modified asphalt were investigated. Then, the characteristics of the inhibition materials were evaluated. Finally, the reduction in the emission of inhibited crumb rubber-modified asphalt fume was identified, and the optimized formula was determined based on the inhibition effect, rheological properties, and cost. The results indicate that crumb rubber-modified asphalts release more fume components with an increment in the temperature and crumb rubber content. Desulfurized rubber reduces the release of H2S and NO. Benzene compounds, including paraxylene, toluene, and benzene, are the most released pollutants that harm human health, especially DS CRA 20% and CRA 50%. Kaolin powder and expanded graphite have a sufficient pore structure and volume, the addition of which reduces the release of pollutants while possibly promoting the release of NO and H2S. Their addition also has a significant control effect on the release of particulate matter at 170 °C and 185 °C. With the consideration of emissions, rheological properties, and cost, CRA 40%-EG2%-KL2% was determined as the optimization formula. This research is helpful to the application of crumb rubber-modified asphalt in road construction and maintenance. [ABSTRACT FROM AUTHOR]

The issue of forming a reliable and sustainable structure of crumb-rubber-modified binder is an important scientific and technical task. The quality of this task will increase the technical and economic efficiencies of road construction materials. This work is dedicated to developing a scientifically justified method of directed thermomechanical devulcanization, which ensures the solubility of the crumb rubber in the complex structure of a polydisperse composite material, preventing the formation of aggregates consisting of unsaturated crumb rubber particles, whose elastic aftereffect causes intensive cracking, especially during low-temperature road operations. The novelty in the first part of this article is due to the fact that, for the first time, the quantitative ratio of the polymer component in the crumb rubber was experimentally determined. The ratio of the polymer component to the total content of the other rubber components in the crumb rubber (CR) was determined to be, on average, 93.3 ± 1.8%. The stabilities of the compositions of crumb rubber from different batches were experimentally studied. The nature of the polymer component in the crumb rubber was determined. A hypothesis was formulated to obtain a thermodynamically stable and sustainable binder modified with crumb rubber. To evaluate the compatibility of hydrocarbon plasticizers with the studied CR samples, the following semi-empirical and thermodynamic compatibility parameters were calculated: Hildebrand solubility parameters based on evaporation energy and surface tension, Barstein's compatibility parameter |X|, Traxler coefficient, and the mass ratio of paraffin naphthene:asphaltenes. It was shown that for the substances under study, it is advisable to justify the choice of plasticizer based on chemical compatibility criteria. It was established that a supramolecular plasticization mechanism occurs in the "hydrocarbon plasticizer–crumb rubber" systems under consideration. In the development of the crumb-rubber-modified binder, it was found that the use of activated crumb rubber (ACR) from large tires does not ensure the achievement of a stable and resilient structure of the crumb-rubber-modified bitumen. [ABSTRACT FROM AUTHOR]

To address environmental pollution caused by waste tires, civil engineers have attempted to utilize waste tires in the construction of building structures and infrastructures, thereby conserving natural structural materials. Because of the pyrolysis of rubber at high temperature, crumbed rubber concrete (CRC) used in high‐temperature conditions or fire resistance engineering has several limitations. This study used crumbed rubber (CR) particles to replace fine aggregate in equal volume and fulfilled steady‐state tests at high temperatures to investigate the failure modes and mechanical behavior of CRC subjected to high temperatures. The effects of rubber content (0%, 10%, and 20%) and particle size (0.106, 0.425, and 2 mm) on the elastic models, ultimate compressive strengths, and peak strain of CRC mechanical properties were investigated using scanning electron microscopy analysis. The test results showed that at the same temperature, the mechanical properties reduced as the CR content increased. When suitable particle sizes of CR were employed, the reduction in the mechanical properties was slower compared to when CRC utilized smaller or larger particle sizes of CR. Because of the filling pores in CRC after CR decomposition at high temperatures, the compressive strength and elastic modulus of CRC fluctuated significantly. [ABSTRACT FROM AUTHOR]

The impact of polyphosphoric acid (PPA) polymers and crumb rubber (CR) on bitumen's properties to enhance its performance was examined in this study. Laboratory samples were created with varying percentages of PPA (0.5% to 2%) and CR (6% to 18%) and subjected to extensive testing. Findings indicated that the combination of PPA and CR led to notable improvements in bitumen performance, including increased viscosity, softening point, elasticity, and recovery rates at elevated temperatures. Specifically, samples with 18% CR and 1.0% or 2.0% PPA demonstrated exceptional rheological properties and strength. The optimal combination (18% CR and 1.0% PPA) resulted in a uniform structure, while the maximum CR content did not compromise bitumen integrity. Both additives effectively minimized temperature sensitivity and aging, enhancing the bitumen's performance class significantly. [ABSTRACT FROM AUTHOR]

The article discusses the use of rubberized concrete in reinforced concrete columns and its performance under axial and cyclic loads. The addition of crumb rubber to the concrete reduces its compressive strength and load capacity but improves its displacement ductility and damping ratio. The study suggests that rubberized concrete can enhance the performance of concrete columns under cyclic loading and delay the onset of earthquake damage. The article provides a technical analysis of various parameters and their implications for the seismic performance of rubberized concrete. [Extracted from the article]

Polymers, rubber, carbon black, nanomaterials, and other substances are frequently used for producing modified asphalt binders, which strengthen their ability to withstand fluctuating temperatures and growing vehicular loads. In order to achieve the intended performance, crosslinking agents/additives are frequently utilized to enhance the compatibility of various modifiers with the asphalt binder. This literature review paper provides a discussion on the use of different crosslinking agents, such as sulfur, dithiodimorpholine (DTDM), tetraethyl thiuram disulfide (TETDS), polyphosphoric acid (PPA), trans-polyoctenamer rubber (TOR), and peroxide, in the formulation of modified asphalt binder with different polymers, such as styrene-butadiene-styrene (SBS), ethylene vinyl acetate (EVA), and polyethylene (PE), as well as different rubber modifiers, such as styrene-butadiene rubber (SBR), crumb rubber (CR), and ethylene-propylene-diene-monomer (EPDM) rubber. The fundamental concepts of the chemistry of modified asphalt binder are covered first, and then various crosslinking additives/agents and their effects on the storage stability/compatibility and chemical and rheological properties of modified asphalt binder are reviewed. The environmental effects of using these crosslinking agents with modified asphalt binders are also covered in the present work. The paper concludes with recommendations for future research studies using crosslinking agents with different types of modified asphalt binders. [ABSTRACT FROM AUTHOR]

The increasing manufacturing of tires, driven by the automotive sector, has led to various sustainability and waste management issues. Consequently, it is necessary to explore alternatives for the reuse of these wastes. Rubber has demonstrated properties that could make it an attractive material for use as a granular aggregate. The aim of this study is to evaluate the influence of crumb rubber (CR) on the mechanical behavior of a granular subbase (GSB) by replacing fine CR at 10% and 15%. An environmental analysis of the proposal was conducted using the SimaPro tool, and a series of laboratory tests were performed to assess physical and mechanical characteristics. The strength results indicate a decreasing trend as the CR content in the GSB increases. Specifically, in abrasion tests, the natural material showed an average result of 30.86%, while the mixes with 10% and 15% CR exceeded the maximum limit (50%), achieving results of 59.24% and 53.98%, respectively. In terms of the California Bearing Ratio (CBR), only the natural samples compacted at maximum energy exceeded the minimum requirements for low and medium traffic levels (30%). The highest CBR value for samples containing CR was 5%, whereas the natural GSB reached a maximum CBR of 33%. A similar trend is observed in environmental outcomes, with increases of up to 17% in abiotic depletion for the sample with 15% CR. Overall, the environmental analysis suggests that incorporating CR into the GSB could lead to an increase in various environmental impacts. [ABSTRACT FROM AUTHOR]

This study aims to employ the maximum allowed amount of waste materials in the roller- compacted concrete (RCC) mixture using three types of waste materials, namely slag, reclaimed asphalt pavement (RAP) and crumb rubber. A mix design, including recycled materials with the maximum amount allowed to be used in the mixture, is presented by combining alternative materials and covering defects of each alternative material with another alternative material. To make samples containing waste materials, crumb rubber replaces the material passed through the 3/8-inch sieve and remains on sieve no. 50, RAP as the main material replaces coarse aggregates and slag replaces the remaining part of coarse aggregates after RAP replacement. Compressive strength, flexural strength and indirect tensile strength tests are used to evaluate RCC mixture performance. The results indicate increasing RAP decreases indirect tensile strength and increases flexural strength of samples. Moreover, increasing RAP by 50% increases compressive strength and, then, decreases compressive strength if it exceeds 50%. Adding slag to the mixture increases compressive and indirect tensile strength. Also, increasing slag by 50% increases flexural strength of samples and, then, decreases this strength if it exceeds this value. Increasing crumb rubber by 50% decreases compressive strength by 65% and indirect tensile strength of samples by 59.7% compared to the control sample. Increasing crumb rubber by 15% increases flexural strength and, then, decreases this strength if it exceeds this value. Finally, a RCC sample with 70% RAP, 25% slag and 10% crumb rubber is proposed as the final mix design. [ABSTRACT FROM AUTHOR]

This research investigates reinforced concrete beams with three groups of Glass Fiber Reinforced Polymer (GFRP) bar, Sand-blasted Glass Fiber Reinforced Polymer (SGFRP) bar and steel bar with concrete containing recycled materials with different concrete mix design before and after applying elevated temperature. The concrete mix designs include replacing glass powder and micro-silica with a part of concrete cement and replacing waste crumb rubber and glass crumb with a part of fine and coarse concrete aggregate. The beams were subjected to high temperature up to 600 °C in an electric furnace, and then subjected to the flexural strength test. The results showed that applying elevated temperature to beams reinforced with composite bars caused a sharp drop in flexural strength. The beam exposed to high temperature containing glass powder, coarse rubber and micro-silica had 2.2 times more flexural strength than the reference beam exposed to high temperature, and the beam not exposed to high temperature in this mix had 36% more flexural strength and 54% more ductility than the reference beam that was not exposed to high temperature. The beam with SGFRP bar with sand coating showed higher flexural strength after applying elevated temperature than the beam with GFRP bar with normal surface. In general, the replacement of recycled materials in the concrete improved the performance of the beams against elevated temperature compared to the beams with normal concrete. [ABSTRACT FROM AUTHOR]

Liquid rubber (LR) has been proven to be a valuable asphalt modifier capable of addressing the existing deficiencies associated with crumb rubber–modified asphalt (CRMA), including poor workability and storage stability. Therefore, an accessible preparation method based on olefin metathesis was explored to produce optimal LR from crumb rubber (CR) in the laboratory. This research established the optimal laboratory preparation conditions for LR and investigated the performance of liquid rubber–modified asphalt (LRMA) mixture when used in pavement. A total of 32 LR samples were generated by olefin metathesis and physical swelling under various catalytic and swelling conditions. The physical properties, viscosity, and storage ability of LRMA were evaluated to select the optimal preparation parameters for LR. A comprehensive analysis was performed to compare the physicochemical characteristics of LR and the original CR through microscopic examinations with scanning electron microscopy (SEM), Fourier-transform infrared spectrometry (FTIR), and gel permeation chromatography (GPC). An in-depth evaluation assessed the stability at high temperatures, the properties at low temperatures, and the moisture stability of LRMA and CRMA mixtures. Experimental results showed that the optimal laboratory preparation conditions for LR were a catalyst dosage between 3‰ and 5‰, a catalytic duration of 48 h, a swelling temperature of 160°C, and a swelling time of 8 h. Moreover, LR possessed a smooth surface without rubber particles. The molecular weight and distribution of LR were considerably reduced compared with those of CR after olefin metathesis and physical swelling. The introduction of LR significantly enhanced the cracking resistance of the base asphalt mixture. However, the enhancement effect of LR on the base asphalt mixture to resist high-temperature rutting and moisture damage was inferior to that of CR. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the behavior of accelerated carbonation-cured laboratory specimens using the ultrasonic non-destructive testing (UNDT) method and compare the results with the destructive testing (DT) method. The materials used in the study included a blend of lime kiln dust and ground granulated blast furnace slag (LKD-GBFS) wastes, natural fine aggregate (sand), and alternative fine aggregates from waste tires. The chemical analysis of the LKD and GBFS samples highlighted them as suitable alternatives to OPC, hence their utilization in the study. A 60:40 (LKD-GBFS) blending ratio and a 1:2 mix design (one part LKD-GBFS blend and two part sand) was considered. The natural fine aggregate was partially replaced with fine waste tire rubber crumbs (TRCs) in stepped increments of 0, 5, and 10% by the volume of the sand. The samples produced were cured using three curing regimens: humid curing (HC), accelerated carbonation curing (ACC) with no water curing (NWC) afterwards, and water curing after carbonation (WC). From the results, an exponential model was developed, which showed a direct correlation between the UNDT and DT results. The developed model is a useful tool that can predict the CS of carbonated samples when cast samples are unavailable. Lastly, a total CO2 uptake of 15,912 g (15.9 kg) was recorded, which underscores ACC as a promising curing technique that can be utilized in the construction industry. This technique will bring about savings in terms of the time required to produce masonry units while promoting a change in the basic assumptions of a safer and cleaner environment. [ABSTRACT FROM AUTHOR]

In recent years the increased traffic, axle load, tire pressure, and hot weather have hastened the spread of rutting in flexible pavements. Recent research indicates that nanomaterials and crumb rubber considerably alter asphaltic mixture characteristics. This research aims to examine the impact of Nano Clay (NC) combined with Crumb Rubber (CR) on the Marshall characteristics and the rutting resistance of HMA. It involves determining the optimal asphalt content, by using the method of Marshall design, as well as the rutting depth for asphalt mixes with varying amounts of NC (1%, 3%, and 5%) and CR (10%, 20%, and 30%) as a percentage of the asphalt binder. The optimal content of asphalt was 4.93% for the control mix. The Marshall stability was enhanced by the inclusion of NC and CR, with the combination of 5% NC and 30% CR exhibiting the most significant increase of 20.9%. Marshall flow was decreased by adding NC and CR. The control mix had a Marshall flow of 3.30 mm, but when using 3% of NC and 30% of CR, the flow decreased to 2.88 mm, which was the greatest reduction. The ideal proportion of NC and CR was 5% and 30%, respectively. This resulted in a 40.85% reduction in rut depth compared to the control mixture. [ABSTRACT FROM AUTHOR]

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To comprehensively investigate the impact of chloride salt erosion on the multiscale bonding behavior between asphalt and aggregate, atomic force microscopy (AFM) and pull-off tests were employed. A thorough study was conducted on the microsurface morphology, nanoscale surface roughness, microsurface energy, and macro pull-off strength between asphalt and aggregate under different chloride salt concentrations. Furthermore, the relationship between the microscopic structural characteristics of asphalt and macroscopic bonding performance was analyzed. The results revealed that, except for the crumb rubber (CR) modified asphalt, the surface of asphalt exhibited an alternation of peaks and valleys forming a beelike structure both before and after chloride salt erosion. The erosion caused the reaggregation of asphalt surface particles, resulting in prominent nano-protrusions and white spots, thereby increasing the surface height and roughness of asphalt. In chloride salt solutions, the infiltration of ions and water molecules into the asphalt may lead to irregular depressions and pits on the surface, consequently reducing the surface energy of the asphalt. This further diminished the effective contact area between the asphalt and aggregates, forming microscopic voids and subsequently weakening the bonding strength at the asphalt-aggregate interface. [ABSTRACT FROM AUTHOR]

Compound modified asphalt with waste plastic and crumb rubber can enhance the application of crumb rubber–modified asphalt (CRMA) in engineering, and enable the recycling of waste resources. In this study, waste cooking oil (WCO) was used to activate crumb rubber and acrylonitrile-butadiene-styrene (ABS) to obtain crumb rubber–modified asphalt with excellent storage stability and low viscosity. The viscosity and storage stability of crumb rubber–modified asphalt were tested by rotational viscosity test and cigar tube test. The force ductility test and bending beam rheological (BBR) test were used to evaluate the low-temperature performance of different crumb rubber–modified asphalt samples. The effect of the addition of waste cooking oil and acrylonitrile-butadiene-styrene on the low-temperature performance of crumb rubber–modified asphalt was explored by using the Burgers model fitting parameters and the ΔTc value between the limit temperature of the critical low-temperature performance grade. The test results showed that cooking oil reduces the rotational viscosity of crumb rubber–modified asphalt, and acrylonitrile-butadiene-styrene enhances its storage stability. When the acrylonitrile-butadiene-styrene and waste cooking oil contents reached 4% and 3%, respectively, the rotational viscosity and separation index values of crumb rubber–modified asphalt decreased by 11.2% and 49.8%, respectively. Waste cooking oil notably enhanced the crumb rubber–modified asphalt's ductility, particularly in the case of crumb rubber–modified asphalt compounded with 4% acrylonitrile-butadiene-styrene and 3% waste cooking oil, exhibiting the longest ductility and the highest toughness value, which were 85% and 75.6% higher than the original crumb rubber–modified asphalt, respectively. Insights from Burgers model parameters and ΔTc values revealed that waste cooking oil improves CRMA's stress relaxation ability and reduces its critical low temperature, and acrylonitrile-butadiene-styrene has no adverse impact on CRMA's resistance to low-temperature thermal cracking. Fourier transform infrared spectroscopy (FTIR) test results demonstrated that the addition of acrylonitrile-butadiene-styrene does not lead to a chemical reaction with crumb rubber–modified asphalt. [ABSTRACT FROM AUTHOR]

Waste tires, used in combination with polymers, have been extensively employed in the construction of asphalt pavements. The performance of these hybrid asphalts varies depending on the manufacturing process, the characteristics of the neat binder, and other factors. The present study aims to investigate the effect of crumb rubber, polymer, and neat asphalt on physicochemical and rheological properties of terminal blend rubberized asphalt (TBRA). Thermal gravimetric (TG) testing was performed to analyze the component distribution of different crumb rubber modifiers (CRMs). Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and solubility and storage stability tests were used to characterize the physicochemical properties of TBRA binders. The rotational viscosity (RV) test, high-temperature performance grade (PG), and rheological master curve were used to compare the rheological properties of various TBRA binders, respectively. Results indicated that crumb rubber and neat binder characteristics, as well as the addition of polymer, impact TBRA performance. However, the influence of neat binder and polymer is more significant than that of crumb rubber. The primary differences in the physicochemical properties of TBRA prepared with different crumb rubber types are related to solubility and degradation degree. The interaction between Zhonghai neat asphalt and crumb rubber is weaker than that of ESSO and Jinshan asphalt, as evidenced by a comparison of molecular weight distribution. Moreover, 3.0% styrene-butadiene-styrene (SBS) polymer can significantly improves the elastic property of TBRA produced with ESSO neat asphalt, which is evidenced by similar phase angle plateau region with 4.5% SBS modified asphalt. [ABSTRACT FROM AUTHOR]

Although crumb rubber (CR) modified bitumen has been widely used in bitumen pavement, the issue of storage stability has not been resolved. Waste low-density polyethylene (LDPE), a new modifier, has been introduced to improve the performance of CR-modified bitumen. However, the interaction behavior among LDPE with different ultraviolet (UV) aging degrees, crumb rubber, and bitumen is not clear, depending on the environment and source. In this study, virgin LDPE (LDPE-0)/CR blends, LDPE with 8 days UV aging (LDPE-8)/CR blends and LDPE with 64 days UV aging (LDPE-64)/CR blends were prepared by melt compounding using a twin-screw extruder and mixed with bitumen. The samples were evaluated by various tests such as dynamic shear rheometer (DSR) tests, storage stability, fluorescence microscopy, and scanning electron microscope (SEM). Then, molecular dynamics (MD) simulation was used to explore the interaction behavior between LDPE/CR blends with different UV aging degrees and bitumen. The virgin bitumen model was validated by density, radial distribution function (RDF), and glass transition temperature (Tg). The interaction behaviors were characterized based on diffusion coefficient and concentration distribution. The results showed that LDPE/CR blends were able to improve the rheological properties and storage stability, especially in LDPE-8/CR-modified bitumen. From the microscopic analysis, it was also observed that a network of LDPE/CR blends in the modified bitumen was well dispersed. Furthermore, the addition of LDPE/CR blends inhibited the aggregation behavior of the light component and slowed down the diffusion rate of bitumen molecules. The research findings provide insights for improving the storage stability of bitumen. [ABSTRACT FROM AUTHOR]

The higher production temperature and greenhouse gas emissions restrain the use of crumb rubber (CR) obtained from recycled tires in pavement construction. Warm mix asphalt (WMA) technology is a sustainable solution for crumb rubber–modified bitumen (CRMB) as it allows the production of asphalt mixtures at lower temperatures. In addition, WMA lowers fuel consumption and greenhouse gas (GHG) emissions, leading to the cleaner production of asphalt mixtures. The primary objective of the study is to minimize the production temperature of crumb rubber–modified (CRM) binders with the use of WMA technology. This study explores the mixing and compaction temperatures using a workability approach. The study found that the conventional viscous-based methods do not yield appropriate production temperatures for CRM asphalt binders. The workability approach used in this study was able to quantify the mixing and compaction temperatures for different CRM mixture incorporated with WMA technologies. About 4%–13% and 5%–22% reduction in mixing and compaction temperatures, respectively, were obtained for different WMA technologies. Finally, the reduction in GHG and energy consumption were studied for WMA technology at their reduced mixing and compaction temperature. The use of WMA technology reduced the energy consumption by around 4%–12% and GHG emissions by 4%–13% relative to base CRM mixture. The amount of reduction in emission and energy consumption was found to be the function of fuel type, WMA additives, and their respective dosages. [ABSTRACT FROM AUTHOR]

This paper attempts to evaluate the change in the behavior of the acoustic waves associated with flexure cracks developed in rubberized concretes in a subfreezing environment. Seven normal and rubberized concrete mixtures were developed with different compositions. Prism samples from each mixture were tested at two temperatures (25°C and −20°C) under a four-point monotonic flexure test while being monitored via two attached acoustic emission (AE) sensors to collect the emitted AEs till failure. The AE signal characteristics such as signal amplitudes, number of hits, and cumulative signal strength (CSS) were collected and used for three AE parameter-based analyses: b-value, intensity, and rise time–amplitude (RA) analysis. Analyzing the acoustic activity revealed micro- and macrocracks nucleation, which were found to be associated with a noticeable spike in CSS, historic index [H(t)], severity (Sr) values, and a significant dip in the b-values. In addition, cold temperature was found to increase the micro- and macrocracking onset load and time regardless of mixture composition. Besides, mixtures with a lower C/F, less crumb rubber (CR) content, and/or smaller rubber particle size witnessed higher micro- and macrocrack load and time thresholds. Noticeably, the AE signal attenuation effect caused by the high CR content (up to 30%) at 25°C was significantly relieved when samples were tested at −20°C. Three charts were developed to classify the cracking level based on the values of the intensity analysis parameters [H(t) and S] and RA analysis. Practical Applications: Infrastructure failures can cause severe economic losses and fatalities, but luckily they can be avoided through regular inspections with the aid of nondestructive testing and subsequent repairs. Aging structures need more inspections to detect potential deficiencies, whereas newly constructed ones can safely undergo fewer inspections and preserve resources. Data from nondestructive testing programs can optimize inspection schedules. When it comes to hard-to-reach structures in extreme weather, acoustic emission (AE) has the potential to be a more suitable nondestructive testing technique over other conventional methods. Some concerns were raised regarding the effectiveness of the AE technique for applications involving novel construction materials such as rubberized concrete, because rubber particles have noticeable acoustic absorption capacities that may affect the parameters of the AE waves and impact the posttesting analysis. Another concern was the influence of cold temperature on the AE wave characteristics due to the change in concrete microstructure at low temperatures. This study aimed at addressing these concerns by utilizing AE analysis to highlight the onset of micro- or macrocracks in rubberized concrete mixtures exposed to cold temperatures. Three user-friendly charts are presented that can advise on inspection decisions based on whether deterioration has reached a certain level. [ABSTRACT FROM AUTHOR]

To alleviate the application limitations of cement-stabilized soil in impermeable engineering and promote the recycling of waste rubber tires, crumb rubber produced from waste rubber tires was used to improve the engineering properties of the soil. The effect of crumb rubber on the permeability of the soil under different conditions was investigated using compression, compaction, and permeability tests. Crumb rubber can effectively improve the impermeability of cement-stabilized soil. The impermeability efficiency of crumb rubber is between 11% and 45%. Cleaning crumb rubber with water and Na2CO3 solution can reduce the hydraulic conductivity of rubberized cement-stabilized soil (RCSS) by 7.9%–63.6%. This, in turn, increases the unconfined compressive strength by 4.1%–25.5%. The hydraulic conductivity of the RCSS decreases with an increase in the cement content, curing duration, and void ratio. A crumb rubber concentration of 10%–20% is suitable for enhancing the impermeability of the RCSS and satisfying its strength requirements. The NOF of the equation used to predict the hydraulic conductivity of the RCSS by the rubber content, cement content, and curing duration is less than 0.35. The linear correlation between the predicted and measured values of hydraulic conductivity was determined to be 0.995 from the k-quc correlation model. The results show that the hydraulic conductivity of RCSS can be estimated reliably based on the mix ratio and compressive strength. [ABSTRACT FROM AUTHOR]

Devulcanized rubber-modified asphalt (DRMA) possesses broad application potential due to its environmental friendliness and exceptional performance. However, the relationship between the rubber devulcanization degree, rubber content, and the modification effect of asphalt binder has not been clearly revealed. In this work, DRMA with different rubber devulcanization degrees and contents was prepared. The storage stability and rheological properties of several asphalt binders were evaluated, and the interaction mechanism between different devulcanized rubber (DVR) and asphalt was also detected. The storage stability of DRMA increased with the rubber devulcanization degree and decreased with the DVR content. The rheological test results demonstrated that under the same rubber devulcanization conditions, the elasticity ratio, rutting resistance, and fatigue resistance of the ML40 series was enhanced continuously, while the above properties of DRMA of the other series were enhanced and then weakened with the rubber devulcanization degree. Additionally, the DRMA of the ML60 series had a superior elasticity ratio and rutting resistance when the DVR content was the same. The low-temperature performance of DRMA increases with the rubber devulcanization degree and DVR content. [ABSTRACT FROM AUTHOR]

Concrete is the second most common material demanded over the world. Recently, a trending issue is the vast tracking in constructing infrastructure to ensure traffic movement and life quality. Concrete types such as self and rolled compacted concrete offer magical solutions ensuring vast infrastructure and life quality. However, these structures must be assessed using non-destructive testing methods to observe the difference between the concrete types. Several studies have used recycled waste, specifically the crumb rubber extracted from old tires, as a potential replacement for natural aggregate in concrete manufacturing. However, limited research has been devoted to nondestructive testing of produced concrete to further evaluate existing concrete elements containing crumb rubber. This study investigates the self and rolled compacted concrete in comparison with normal ones, in addition to using chopped rubber as recycled materials. This study examines the concrete manufactured destructively by evaluating its compressive, tensile, and flexural strength, in addition to impact resistance, and correlates those results with the non-destructive such as Schmit hammer and Ultrasonic Pulse (UPV) for extended utilization of the concrete produced and data publication. The results showed unique performance and a high potential for data contribution to the extensive utilization of self-compacted rubberized concrete and rolled compacted concrete. [ABSTRACT FROM AUTHOR]

The concrete industry is increasingly adopting the production of environmentally sustainable green concrete. Using recycled coarse aggregate (RCA) produced from demolished concrete infrastructures and waste tire-derived crumb rubber (CR) in the concrete mixture provides a sustainable construction practice and can enhance structural performance. This study investigates the uniaxial compressive behavior of concrete columns composed of RCA, CR, and polypropylene (PP) fiber. A total of 26 columns 150 x 150 x 950 mm in size were tested under uniaxial compression loading. Test parameters included longitudinal reinforcement ratio (0, 1.4, and 2.0%), tie spacing (75 and 150 mm), CR content (0, 5, 10, and 15% of the volume of natural fine aggregate), and percentage of PP fiber (0 and 0.5% of the volume of the total mixture) with 30% RCA replacement (by weight of natural coarse aggregate). The compressive behavior, failure mechanism, influence of longitudinal and transverse reinforcement, dilation, ductility, and toughness were examined. This study demonstrated that incorporating fiber into the concrete made with RCA and CR waste materials improved the axial capacity, resulting in fiber-reinforced rubberized recycled concrete (FRRC) columns with enhanced ductility and toughness. These findings support the development of sustainable concrete for structural columns, justifying their applicability to existing design codes. [ABSTRACT FROM AUTHOR]

Abstract Clayey soils present challenges in engineering applications due to their inherent properties, such as low shear strength, which usually limits their use in engineering applications. Stabilization of clayey soils is crucial to enhance their performance and suitability for various purposes. Utilizing waste materials like discarded tyres and tile powder as soil stabilizers presents a sustainable solution to mitigate environmental concerns while enhancing soil properties. While previous studies have explored using either crumbled rubber or tile powder independently for soil improvement, their combined effect remained largely unexplored. This study addresses this gap by investigating the synergistic potential of blending crumbled rubber and tile powder to enhance the strength and ductility of clayey soils. A series of laboratory tests were conducted to investigate the combined effect of crumbled rubber and tile powder. First, varying percentages of crumbled rubber (2.5%, 5.0%, 7.5%, and 10%) were mixed with the soil, and standard proctor tests, California bearing ratio (CBR) tests, and unconfined compressive strength (UCS) tests were performed. Results showed optimal performance at 5.0% crumbled rubber, exhibiting the highest values for maximum dry density, CBR, and UCS. Subsequently, different percentages of tile powder (5%, 10%, 15%, and 20%) were added to the soil-rubber mixture (with 5% crumbled rubber). The addition of 15% tile powder to the 5% crumbled rubber mixture yielded the most significant improvements as maximum dry density (MDD) increased from 1.842 g/cm3 (raw soil) to 1.963 g/cm3, UCS increased from 0.5176 kg/cm2 (raw soil) to 2.606 kg/cm2, and CBR increased from 1.757% (raw soil) to 7.84%. The addition of crumbled rubber was found to shift the failure behaviour of the clayey soil from brittle to more ductile, indicating an enhanced ability to undergo deformation before failure. This study’s findings highlight the potential of combining crumbled rubber and tile powder as a sustainable solution for enhancing clayey soil properties, paving the way for further research into optimized mixture designs and expanded applications in geotechnical engineering.

The recycling and reuse of solid wastes mark the construction industry's development towards sustainable and green technologies. 3D printing technology using recycled solid materials is in great demand for intelligent and low-carbon construction. This paper incorporates crumb rubber (0–1 mm) into the printing ink and analyses the fresh and hardened properties. The results showed that the flowability was positively correlated with rubber ratio but negatively with fiber content. R40F15 (40% rubber and 1.5% fiber) obtained the optimal flowability for 3D printing, which remained above 15 mm for 30min. The compressive strength peaked when incorporating 1.5% fiber, while the flexural strength reached the bottom. X direction generated the highest compressive strength in the whole anisotropic tests, followed by the Y and Z directions. The highest strengths of 1.5% and 2.0% fiber content were 69.45 MPa and 64.5 MPa, incorporating 20% rubber. Thus, surfaces anticipated to bear higher loads in compression should be aligned with the X-axis or, at a minimum, avoid alignment with the Z-axis for optimal structural performance. Y direction obtained the highest flexural strength in all anisotropic tests when incorporating 1.5% fiber. Results from digital image correlation test supported that fiber tended to agglomerate in the Y direction. Besides, the environmental analysis was conducted in this paper to quantitively calculate the impacts of all raw materials to the environment.

In the current study, multi-walled carbon nanotubes (MWCNTs) were added to the crumb rubber concrete (CRC) to enhance its physical, mechanical, and fire-resistance properties. A comprehensive investigation into thirteen distinct concrete mixes incorporating rubber aggregate (RA) at levels of 5, 10, and 15%, combined with varying percentages (0, 0.1, 0.2, and 0.3%) of MWCNTs particles, evaluated workability, density, compressive strength, split tensile strength, and flexural strength of MWCNT-mixed CRC at ambient and elevated temperatures (200, 400, and 600 °C). The study demonstrated that MWCNTs, used as a partial substitute for cement in CRC, significantly improved concrete properties, enhancing density, flexural strength, split tensile strength, and compressive strength. Notably, adding 0.2% MWCNTs to CRC resulted in remarkable increases: 0.96% in density, 21.91% in 28-day compressive strength, 10.19% in split tensile strength, and 15% in flexural strength. The workability of CRC decreased with the inclusion of MWCNTs. Furthermore, results indicated that MWCNTs bolstered the residual compressive, tensile, and flexural strengths of rubberized concrete at elevated temperatures, with substantial improvements particularly evident at 200 °C. The present work was focused on the analysis of feasibility of MWCNT mixed CRC toward sustainable construction practices by comparing its physical, mechanical, and fire resistance properties with conventional concrete. [ABSTRACT FROM AUTHOR]

Several researches conducted on rubberized concrete in the past but very few researchers explained the bonding effect of the waste tire rubber particles with different cementitious materials. In this research the effect of the fineness of the micro silica and its bonding with the rubber particles is studied. To check the influence of fractional replacement of cement using micro silica and discarded tire rubber as limited substitution of sand with providing pre-treatment to rubber particles, this experimental investigation has been conducted on concrete with varying percentage switch of cement using micro silica (SF), especially micro-silica was used in this study to exchange with cement by its weight. SF exchanged cement from 0% to 12% with an incremental ratio of 3%. Along with this, the sand was fractionally replaced using pretreated crumb rubber (CR) particles derived from end-of-life tires. The replacement ratio changed by 5% by the volume of sand, ranging from 0% to 20%. The pre-treatment process for CR was done using Sodium Hydroxide (NaOH) of 1 Molarity, for achieving good bonding between cementitious material paste and rubber particles. Distinct fresh and hydrated concrete properties were assessed and compared with normal concrete (NC) having 0% SF and 0% CR. 17 concrete mixtures in all, together with the control mix, were assessed in this study with varying amounts of SF and CR. The bonding structure and impermeability were enhanced by using SF in concrete with promising enhancement in mechanical strengths. Based on the outcomes obtained from this research, the optimal proportion for partial substitution of cement and sand by SF and CR was fixed for the desired grade of concrete to provide an innovative form of concrete to the construction industry.

Considering the seismic conditions of Iran and the many damages that occur as a result, it is necessary to change the current performance of structural design to achieve better performance in the seismic system. On the other hand, environmental concerns have prompted civil engineers to identify appropriate methods of reusing construction waste. The purpose of this research is to investigate the behavior of concrete made with recycled materials as a wide foundation, which has the role of seismic isolation for low- or medium-height buildings. In this research, the effect of crumb rubber and recycled concrete aggregate on concrete was examined in a laboratory. The design basis of its resistance is 30 MPa. The first mixture, as a control mixture, does not contain rubber granules, Forta fibers and recycled concrete aggregate. In the other three mixtures, the difference in the amount of recycled concrete aggregate is 40%, 50%, and 60% instead of coarse aggregate. Also, the percentage of rubber granules is constant, about 15% of the total volume, and the amount of Forta fibers is about 0.5% of the total volume. Compressive strength, Flexural strength, and Shear strength tests were performed on the 4 mentioned mixtures at the age of 28 days in a laboratory. The results of the compressive strength test showed that the addition of recycled concrete aggregate, rubber granules, and Forta fibers significantly reduced the compressive strength value. The results of the flexural strength test indicated that the additives cause a noticeable reduction in flexural strength, and this reduction intensifies with the change in recycled concrete aggregate percentage. The results of the shear strength test represented a considerable increase with the increase in the percentage of recycled concrete aggregate. Based on the test results, it is concluded that this type of composition material can be used as a foundation isolator, which showed a favorable shear behavior.

Roller-compacted concrete pavement (RCCP) is a brittle material with low tensile strength that does not contain steel or dowel bars. This, in addition to the rigidity of the RCCP, causes degradation or cracking before the RCCP reaches its service life. To improve the performance of the RCCP, crumb rubber (CR) can be used as an aggregate. Hence, in this study, CR was used to replace 0, 10, 20, and 30% of the fine aggregate in the RCCP. To mitigate the adverse effect of the CR on the properties of the RCCP, nano-silica (NS) was added by weight of cement in proportions of 0, 1, 2, and 3%. To select an optimal mix based on various performance criteria, multicriteria-based optimization was carried out using techniques such as order of preference by similarity to ideal solution, evaluation based on distance from average solution, weighted sum model, and weighted product model techniques. During experimentation, CR improved the consistency and reduced the mechanical and durability properties of the RCCP, while NS reduced the consistency and improved the mechanical and durability performance of the RCCP. The M2 mix (mix containing 0% CR and 1% NS) is consistently ranked as the best choice for multi-criteria decision-making techniques and sensitivity analyses due to its exceptional physical, mechanical, and durability attributes, ensuring reliability across various decision-making scenarios. This study provides insights into the decision-making process for the choice of appropriate RCCP mix produced with CR and NS for improved performance in pavement applications and the importance of utilizing waste tire rubber in concrete pavements to promote sustainability.

At present, the need to make use of industrial waste materials is increasing due to their harmful effects on the environment. In the present work, the behavior of hybrid reinforced T-Beam by steel, and CFRP with rubber is studied. The finite element modeling by using ANSYS version 15 program. It contains also all the required steps needed to create the concrete models that were prepared to study the behavior of beams with rubber concrete. The reinforcement of beams was various combinations of polymer CFRP and steel bars. The crumb rubberized concrete mixes were prepared by partial substitution (5 %, 10 %, 15 %, 17.5 %, 20 %, 22.5 %, and 25 % replacements by volume). Due to the large number of parameters affecting the behavior of Hybrid Reinforced T- Beam with rubber concrete, an extensive parametric study was performed using ANSYS version 15 program. Three parameters were investigated namely: Bottom RFT, compressive strength of concrete, and the existence of opening. The analytical results agree well with the experimental results in terms of mode of failure and the failure load values. The results indicated that although the flexural capacity of the tested specimen decreased with the addition of Crumb Rubber and reduced its self-weight. The failure load of the beam increases with bottom reinforcement by the GFRP bar or CFRP bar. Also, reinforced beams by CFRP bars had a higher failure load than reinforced beams by GFRP bars. Having an opening in hybrid reinforced T-Beam with rubber concrete reduced the beam load capacity and maximum deflection. Also, using GFRP bars, and CFRP bars in the vicinity of openings in hybrid reinforced T-Beams increased the load capacity of these beams.

Measures should be taken to prevent the effects of vibration caused by dynamic loads of machines. Research has shown that trenches can effectively reduce vibrations caused by machine foundations. It has been determined that the open trench provides the best performance against vibration, but it is not practical due to operational limitations. Considering environmental concerns and vibration absorption, rubber crumb can effectively combine with sand in trenches. Combining rubber crumbs and sandy soil in the trenches reduces vibration from industrial machines and promotes the reuse of rubber waste. This article examines how surface trenches filled with a sand and rubber crumb mixture can reduce the vibrations of industrial foundations. This research focuses more on vibrations and high strains, and vibrating foundations have been used for vibration. The study aimed to determine the impact of trench dimensions on insulation levels. The results indicated that trench length and depth had a significant effect, while thickness did not have a noticeable impact. The study also examined different trenches with varying combinations of crumb rubber to determine their isolation level. The trenches contained 30%, 20%, and 10% crumb rubber by weight, and the average isolation values were 58.20%, 56.33%, and 50.29%, respectively. The results were then compared with each other. [ABSTRACT FROM AUTHOR]

Rubberised concrete is a type of light, green building material, which is prepared by mixing rubber powder or rubber crumb into ordinary concrete in a certain proportion. Similarly, using vibration-free technology, rubber can be added to self-compacting concrete (SCC) to prepare self-compacting rubber concrete (SCRC). Uniaxial compression tests were carried out on SCRC made with two particle sizes at different strain rates, and the effects of strain rate and rubber content on the dynamic mechanical properties of the SCRC were studied. The microstructure of SCRC specimens before and after damage was analysed. Compared with ordinary SCC, the SCRC was capable of maintaining good integrity during damage when the rubber powder content exceeded 10% and the rubber crumb content exceeded 15%. It was also found that, as the strain rate increased, both the peak stress and the elastic modulus increased, indicating the strain rate enhancement effect; the strain rate effect on the peak strain was not evident. Equations relating peak stress and elastic modulus to the strain rate effect were established, a dynamic damage constitutive model was developed, the damage evolution was analysed and stress intervals were assigned to the various stages of damage evolution. [ABSTRACT FROM AUTHOR]

Microplastics accumulate in the environment but methods to extract particles from sediment for quantification and identification often lack accuracy and reproducibility. Existing methods vary greatly and many do not achieve adequate microplastic separation. During method development for extraction procedures, spike-recovery experiments (positive controls) are essential to ensure accurate and reproducible results from each sample matrix. Furthermore, the large variability in grain size and organic matter can affect the extraction of microplastics from the matrix. Scientists have used density separation to separate microplastics from matrices for decades, but apparatuses are often made of plastic, need to be custom made, and require multiple sample transfers from one apparatus to another. This study presents an affordable, easily accessible, and simple to use Density Separation Device (DSD) to remove plastics from deep-sea sediments. Eight polymers were spiked into replicates of environmental sediment, including six fragments: high density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), nylon (PA6), and crumb rubber (CR) and two fibers: cellulose acetate (CA) and polyester (PEST). Two size classes of polymers were used: 100 μm to 300 μm and > 300 μm. Using a sodium polytungstate solution at a density of 1.9 g/mL and reflectance FTIR microscopy for particle identification, mean recoveries of all fragments exceeded 78% (CR: 92.7% ± 30.8%, PP: 78.4% ± 34.0%, HDPE: 93.8% ± 13.5%, PS: 86.9% ± 25.7%, PA6: 98.4% ± 63.2%, PVC: 100.0% ± 12.4%). Fiber recovery was much lower (PEST: 28.1% ± 28.1% and CA: 25.9% ± 17.3%) because they aggregated, passed through sieves vertically, or were obscured under other particles. The fragment recovery success, accessibility (available online, all parts under $200) and ease of use of this DSD should facilitate widespread use, thus helping to standardize sample preparation methods for microplastic metrology. [ABSTRACT FROM AUTHOR]

This study investigates the transformative effects of incorporating Trinidad Lake asphalt (TLA), crumb rubber modifier (CRM), and the warm mix additive leadcap (LC) into petroleum-based asphalt binder PG 64-22. Our results show that LC significantly reduces binder viscosity, leading to easier application and lower energy consumption, especially when combined with TLA and CRM. The addition of TLA and CRM enhances rutting resistance, with notable improvements in both pre- and post-aging conditions, particularly in formulations combining PG 64-22, 20% TLA, and 10% CRM. These formulations exhibit superior performance metrics, such as increased percentage recovery (% rec) and reduced non-recoverable creep compliance (Jnr), indicating improved flexibility and deformation resistance. Furthermore, LC balances increased rigidity and susceptibility to fatigue cracking from higher TLA and CRM levels, respectively. These modifications also promote environmental sustainability by reducing energy usage and emissions during production and paving. This study highlights LC's critical role in advancing high-performance, eco-friendly warm mix asphalt binders, offering valuable insights for sustainable pavement engineering and setting a new benchmark for advanced asphalt technologies. [ABSTRACT FROM AUTHOR]

Untreated pyrolytic tire char was used in natural rubber (STR20) composites as single filler at loadings of 30–70 phr and co‐filler with carbon black (N330) at a total loading of 50 phr. The results were compared with rubbers filled with N330 and crumb rubber at 30 phr. The effects of fillers on cure characteristic, crosslink density, filler dispersion in natural rubber vulcanizates and their mechanical properties were investigated. The slight reversions were seen for the cure characteristics of 70 phr‐char‐filled and all co‐filler samples because the sulfur amount in the char together with the added sulfur could shift the vulcanization system from EV to SEV, whereas plateau cure curves were seen for the rest. While the highest tensile strength of char‐filled sample was obtained at 50 phr loading, whose tensile strength was about 88% of the N330 sample at 30 phr, 70‐phr‐char filled sample was superior in surface hardness, abrasion resistance and tear strength to N330 sample at 30 phr. For rubber with co‐fillers, the mechanical properties depended on the mass ratio of N330 to pyrolytic tire char. Therefore, it is possible to use untreated char as reinforcing filler for suitable applications according to their properties. [ABSTRACT FROM AUTHOR]

AbstractIncorporating the substantial waste generated by the disposal of end-of-life tires into the manufacturing process of self-compacted concrete (SCC) presents a viable and environmentally responsible approach to address significant environmental concerns. An extensive study has been conducted to enhance the technical benefits and viability of using scrap vehicle tires as a substitute for traditional aggregates in concrete, particularly the performance of self-compacting concrete containing crumb rubber from waste tires. This study provides a comprehensive review and evaluation of the data derived from over 43 distinct studies on using crumb rubber (CR) as sand replacement in SCC to emphasize and verify the fundamental characteristics of such concrete. The primary objective of this review paper is to provide an in-depth evaluation of the impact of CR on the performance of SCC in its fresh and physical state. Moreover, in this study, fresh properties, including slump flow diameter, T500, V-funnel flow time, L-box height ratio, J-ring flow diameter, TJ500, J-ring high, sieve segregation, air content, and U-box test, and physical properties including porosity, water absorption, and fresh and dry density have been conducted. It has been found that the addition of CR has a detrimental effect on SCC's physical and fresh characteristics, apart from resistance to segregation. The predicted decrease/increase in the fresh and physical characteristics of the SCC, including CR, was given based on the findings of the studied papers. Furthermore, empirical models that illustrated the relationships between various fresh attributes were established using the findings of the examined research. Moreover, recommendations for future work and directions for this field of research have been detailed. [ABSTRACT FROM AUTHOR]