Rubber Fume Research Articles

Strength and durability characteristics of self compacting recycled aggregate concrete incorporating crumb rubber, fly ash and silica fume

Strength and durability characteristics of self compacting recycled aggregate concrete incorporating crumb rubber, fly ash and silica fume

Improving thermal characteristics and energy absorption of concrete by recycled rubber and silica fume

The two conventional disposal methods as landfilling and incineration of waste rubber raise environmental concerns. It is while burying rubber in concrete enhances flexibility and thermal properties due to its inherent ductility and insulation properties. In this study, a comprehensive approach has been adopted to investigate the effects of the amount and size of rubber particles combined with silica fume on the thermal characteristics, energy absorption, and mechanical properties of concrete, including its workability, specific weight, thermal conductivity, thermal performance, compressive strength, flexural strength, and flexural toughness. In addition, statistical analyses were conducted to evaluate the experimental results. It was observed that in concrete containing 50% fine or 50% coarse rubber aggregates combined with 15% silica fume, the thermal conductivity decreases by 45% and 43%, respectively. The energy absorption of concrete samples with 100% fine or 100% coarse rubber particles increased by 2.8 and 4.5 times, respectively, compared to those with 20% rubber. Appropriate equations were developed to estimate the compressive and flexural strengths of concrete with rubber particles while statistical analyses exhibited error levels of 11% and 15%, respectively, for such equations. The compressive and flexural strengths decreased by an average of 68% and 62%, respectively, in samples containing 100% crumb rubber. Likewise, these factors experienced an average reduction of 73% and 71%, respectively, in specimens with 100% rubber powder compared to those with 20% rubber.

Influence of the Physical and Mechanical Properties of Concrete by Adding Rubber Powder and Silica Fume

The construction sector has been consuming raw materials that are becoming extinct over time; in order to contribute to the sustainability of these resources, the use of wastes that are produced on a large scale and often expelled into the environment without being well exploited, there we have the tire rubber and silica fume. This study seeks to evaluate the physical-mechanical properties of concrete, using rubber powder (RP) and silica fume (SF), as a partial substitute for fine aggregate and cement. Concrete samples were made using 5%, 7%, 11% and 14% of rubber powder plus 3%, 7%, 11% and 15% of silica fume. The physical properties were evaluated by slump, temperature and unit weight tests, while compression, tensile and flexural tests were developed at 7, 14 and 28 days of curing, to analyze the mechanical properties. The results showed that the physical properties maintain acceptable variations, since the deficiencies of the rubber powder are reduced by the silica fume; the properties of compression, flexion and traction revealed that even with 8% of rubber powder plus 7% or 11% of silica fume, the desired resistances can be reached, without presenting increases. It is concluded that partial substitution with rubber powder and silica fume does not contribute significantly to the properties of concrete, however, it can be a great alternative when high strength concrete is not required.

Durability Performance and Thermal Resistance of Structural Self-Compacting Concrete Improved with Waste Rubber and Silica Fume

Waste rubber takes many years to decompose, and thus the increasing number of tires in the world can be characterised as an important environmental issue, which generated the idea of implementing crumb rubber in structural self-compacting concrete (SCC). According to previous studies, up to 15% recycled rubber and 5% silica fume can be used to achieve the required properties of SCC in reinforced structural members with congested reinforcement, both in the fresh and hardened state. Most studies have focused on investigating the mechanical properties of self-compacting rubberised concrete (SCRC), and only a small number of studies investigated the durability and thermal properties, with contradictory findings. This study aims to determine the influence of crumb rubber and silica fume on the durability and thermal properties of SCC, with an emphasis on the selection of environmental exposure classes, the safety of using such a material in reinforced concrete members, and additional serviceability and durability requirements. This was further advanced by investigating the micro-structure of hardened SCC with recycled rubber and silica fume using a scanning electron microscope (SEM). Test results indicate that the combining effect of crumb rubber and silica fume has a positive impact on the thermal and durability properties of SCC.

Fatigue Property Evaluation of Sustainable Porous Concrete Modified by Recycled Ground Tire Rubber/Silica Fume under Freeze-Thaw Cycles

As an environmentally friendly pavement material, porous concrete in seasonal frozen region is often subjected to repeated loads and freeze-thaw cycles. Therefore, the fatigue property of porous concrete under freeze-thaw is extremely important. However, few researches have been reported on the topic. Based on this background, this paper investigates the flexural fatigue property of ground tire rubber/silica fume composite modified porous concrete (GTR/SF-PC) with experimental and mathematical statistical methods. The flexural fatigue life of GTR/SF-PC under different freeze-thaw cycles (0, 15, 30) was tested with three-point flexural fatigue experiment at four stress levels (0.70, 0.75, 0.80, 0.85). Kaplan Meier survival analysis and Weibull model were adopted to analyze and characterize the flexural fatigue life. The fatigue life equations of GTR/SF-PC under different freeze-thaw cycles were established. The results indicate that, duo to the addition of ground tire rubber and silica fume, the static flexural strength of GTR/SF-PC is not significantly affected by freeze-thaw cycles. The flexural fatigue property of GTR/SF-PC is gradually deteriorated under the action of freeze-thaw cycles. Compared with 0 freeze-thaw cycles, the average flexural fatigue life of GTR/SF-PC decreases about 15% and the fatigue failure rate increases about 50% after 30 freeze-thaw cycles, respectively. The fatigue equations with different reliabilities of GTR/SF-PC show that the reliability is inversely proportional to fatigue life, therefore, the appropriate fatigue equation considering freeze-thaw effect is necessary for fatigue design of porous concrete.

Evaluation of Light Cementitious Matrix with Composite Textile Reinforcement from Garment Waste.

The use of recycled waste has been the focus of several studies due to its potential to allow a more sustainable use of construction materials and minimize improper waste disposal in landfills or incinerators. More specifically, garment textile waste has been examined as internal reinforcement of cementitious matrices to increase the deformability and control fissure formation. In this study, polyester textiles are analyzed and incorporated in cementitious composites in order to evaluate their mechanical properties. Results show that significant improvements in mechanical properties of composites are obtained depending on the impregnation treatment applied to the textile waste. In the direct tensile stress test, the waste impregnation with styrene butadiene polymer plus silica fume improved 35.95% in the weft direction and 9.33% in the warp direction. Maximum stress increased 53.57% and 64.48% for composites with styrene-butadiene rubber impregnation and styrene-butadiene rubber plus silica fume impregnation, respectively, when compared to the unreinforced composite. The flexural tensile strength of composites impregnated reinforcements with styrene-butadiene rubber and styrene-butadiene rubber plus silica fume presented increases in strength by 92.10% and 94.73%, respectively, when compared to the unreinforced sample. The impact test confirmed that styrene-butadiene rubber plus silica fume impregnation produced greater tenacity of the composite. In the microstructure, it is confirmed that the impregnated textile reinforcement resulted in composites with greater adhesion between the fabric and the cementitious matrix. Thus, light textile waste is concluded to be a viable construction material for non-structural elements.

Crack width control and mechanical properties of low carbon engineered cementitious composites (ECC)

• An ECC with LC3 binder reinforced with polypropylene fiber designed for tight crack width (less than 50 µm at 1% tensile strain) has been developed. • Crumb rubber at 50% replacement level of fly ash was found to be optimal in balancing tight crack width and compressive strength loss. • Compared with PVA-ECC, the embodied carbon of the PP-ECC was reduced by 40–50%. Engineered Cementitious Composites (ECC) have superior properties with high tensile ductility and tight crack width compared to conventional concrete. The properties of ECC are significantly influenced by the material composition which can be tailored to enhance the sustainability of ECC. Towards this goal, recycled crumb rubber (CR) and silica fume (SF) were used to tailor the properties of a polypropylene-fiber reinforced ECC with a low carbon binder based on limestone calcined clay cement (LC3) in this study. Crumb rubber was found to be effective in enhancing strain-hardening performance and reducing the width of the multiple microcracks. However, a loss of compressive strength was accompanied by an increasing amount of CR. While silica fume or lower w/b ratio enhanced the compressive strength, the crack width of ECC increased at higher SF content or lower w/b. The underlying mechanisms of these trends were traced to the alteration of the matrix fracture toughness and fiber/matrix interfacial bond. Rubber particle bridging was found to contribute to crack width control. The combined use of the LC3 green binder and CR led to a lowering of the embodied and operational carbon footprint of ECC.

Performance Evaluation of Waste Crumb Rubber/Silica Fume Composite Modified Pervious Concrete in Seasonal Frozen Regions

The waste crumb rubber (WCR) and silica fume (SF), as industrial waste and byproduct, are widely used as additives in road construction materials, which can not only realize waste utilization and protect the environment but also reduce the consumption of building material resources. At present, most of the research has focused on the properties of concrete modified only by WCR or SF; there are few studies concentrated on composite modified concrete by the two, especially the study on pervious concrete (PC). This article aims to study the mechanical strength, deformability, and freeze‐thaw (F‐T) resistance of waste crumb rubber/silica fume composite modified pervious concrete (RSFPC). The RSFPC and control specimens were manufactured in the lab. The experiments of compressive strength, flexural strength, flexural failure strain, flexural elastic modulus, and F‐T cycles were conducted. In addition, the properties of RSFPC were compared with WCR and SF single modification PC. The results indicate that the composite modification of WCR and SF can give full play to the advantages of the two materials so that the strength property and elastic modulus of PC will not be decreased and the F‐T resistance and deformability can be greatly improved. Compared to a single modification group by WCR or SF, RSFPC has a more balanced and comprehensive performance, which will greatly expand the application of PC.

Prediction Models for the Mechanical Properties of Self-Compacting Concrete with Recycled Rubber and Silica Fume.

The paper aims to investigate the influence of waste tire rubber and silica fume on the fresh and hardened properties of self-compacting concrete (SCC) and to design multivariate regression models for the prediction of the mechanical properties of self-compacting rubberized concrete (SCRC). For this purpose, 21 concrete mixtures were designed. Crumb rubber derived from end-of-life tires (grain size 0.5–3.5 mm) was replaced fine aggregate by 0%, 5%, 10%, 15%, 20%, 25%, and 30% of total aggregate volume. Silica fume was replaced cement by 0%, 5%, and 10% of the total cement mass. The optimal replacement level of both materials was investigated in relation to the values of the fresh properties and mechanical properties of self-compacting concrete. Tests on fresh and hardened self-compacting concrete were performed according to the relevant European standards. Furthermore, models for predicting the values of the compressive strength, modulus of elasticity, and flexural strength of SCRC were designed and verified with the experimental results of 12 other studies. According to the obtained results, mixtures with up to 15% of recycled rubber and 5% of silica fume, with 28 days compressive strength above 30 MPa, were found to be optimal mixtures for the potential future investigation of reinforced self-compacting rubberized concrete structural elements.

Evaluation of tire rubber surface pre-treatment and silica fume on physical-mechanical behavior and microstructural properties of concrete

The increasing accumulation of tire waste has become a social environmental and public health problem because rubber degradation is extremely difficult to achieve and time consuming. The incorporation of rubber waste in concrete has become a recourse to assist in the disposal of this solid waste. This investigation evaluated the influence of a chemical pretreatment with sodium hydroxide solution (NaOH) on the physical, mechanical, microstructural properties of concretes with two rubber residue contents (15% and 30%) as a natural fine aggregate replacement, and the addition of silica fume (7.5% and 15%) to replace Portland cement. X-ray microtomography and scanning electron microscopy were used to investigate the influence of treatment rubber and silica fume in the microstructure of concretes. The use of rubber in the cement matrix, regardless of the treatment (or lack thereof), decreases the concrete density (lower 10.5%) and compressive strength at 28 d (54%), besides the increase the porosity (18%) than reference concretes. The rubber pre-treatment did not significantly influence the concrete behavior. In contrast, the use of silica fume showed significant compressive strength gains, up to 80% for concretes with 30% of rubber replacement at 28 days. These gains were confirmed by the microstructural analysis and the densification of the interfacial transition zone.

Lifetime cumulative exposure to rubber dust, fumes and N-nitrosamines and non-cancer mortality: a 49-year follow-up of UK rubber factory workers

ObjectivesTo examine associations between occupational exposures to rubber dust, rubber fumes and N-nitrosamines and non-cancer mortality.MethodsA cohort of 36 441 males aged 35+ years employed in British rubber factories was...

Expedition on surface adsorption of N-nitrosodiethylamine from rubber fumes on blue phosphorene sheets – a first-principles insight

In recent days, humans are easily exposed to many work-related health issues. N-nitrosodiethylamine (NDE), which is considered to be a harmful carcinogenic agent released from rubber-based industries imparts a long-lasting effect on human health and immunity system. The current research investigates the ability of the two-dimensional nanomaterial, blue phosphorene nanosheet (BPNS) to detect the presence of NDE in the environment. Besides, the electronic and structural characteristics of BPNS are initially explored and NDE target vapour is permitted to interact with the chief component, BPNS. We have also designed blue phosphorene device to study the adsorption properties of NDE vapours based on current–voltage characteristics. The adsorption attributes are accounted for the target vapour adsorbed chief component, the results suggest that BPNS can be employed in detecting NDE vapours.

Flexural-Fatigue Properties of Sustainable Pervious Concrete Pavement Material Containing Ground Tire Rubber and Silica Fume

With the development of urbanization, pervious concrete has been increasingly used in urban road pavement structures. The objective of this paper was to investigate the effect of stress levels and modifier (ground tire rubber and silica fume) on the fatigue life of pervious concrete and establish the fatigue equations with different survival probabilities. In order to improve the deformability of pervious concrete without sacrificing its strength, ground tire rubber and silica fume were added into pervious concrete. Two kinds of pervious concrete, control pervious concrete and ground tire rubber and silica fume modified pervious concrete, were made in the laboratory. The pervious concrete beam specimens of 100 × 100 × 400 mm were casted, and the static flexural strength and flexural strain of the two kinds of pervious concrete were tested. The fatigue lives of two pervious concretes were tested using MTS fatigue testing machine under four different stress levels (0.85, 0.80, 0.75, and 0.70). The fatigue life was analyzed by two-parameter Weibull distribution. The parameters of Weibull distribution were determined by graphical method, maximum likelihood method and moment method. The Kolmogorov–Smirnov test was used to test the Weibull distribution and the fatigue equations under different survival probabilities were established. The results showed that ground tire rubber and silica fume modified pervious concrete had better deformability while ensuring strength compared to control pervious concrete. The addition of ground tire rubber and silica fume improved the fatigue life of pervious concrete. The two-parameter Weibull distribution was suitable to characterize the fatigue characteristics and predict the fatigue life of pervious concrete. Fatigue equations with different survival probabilities were a good guide for pervious concrete design.

Job-exposure matrix for historical exposures to rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry

ObjectivesTo develop a quantitative historical job-exposure matrix (JEM) for rubber dust, rubber fumes and n-Nitrosamines in the British rubber industry for 1915–2002 to estimate lifetime cumulative exposure (LCE) for a...

Lifetime exposure to rubber dusts, fumes and N-nitrosamines and cancer mortality in a cohort of British rubber workers with 49 years follow-up

ObjectivesTo quantitatively evaluate exposure-response associations between occupational exposures to rubber dust, fumes and N-nitrosamines and cancer mortality in the UK rubber industry.MethodsCompeting risk survival analyses were used to examine cancer...

Combination effects of rubber and silica fume on the fracture behaviour of steel-fibre recycled aggregate concrete

The use of recycled concrete aggregate and crumb rubber in structural concrete is a sustainable way to reduce the detrimental impacts of solid waste on the environment and address the shortage of natural resources. For the safe and economical design of rubberized steel-fibre recycled aggregate concrete (RSRAC), the mechanical behaviour of RSRAC modified with silica fume needs to be properly understood. In the present study, the coupling effects of crumb rubber and silica fume on the fracture behaviour of RSRAC were examined for the first time. The results from a series of tests on a notched beam and cylinder under three-point bending and compression, where the RSRACs were incorporated with crumb rubber with a volume substitution of fine aggregate by 0%, 5%, 10%, 15% and 20%, are presented and discussed. The results indicated that the combination of rubber and silica fume exhibited excellent coupling effects on the fracture performance of RSRAC. Regarding reducing the negative effects of rubber, the replacement of 10% cement by silica fume was superior to the addition of 3% silica fume. When considering the mechanical improvement, the RSRAC with 5% rubber and 10% silica fume seems to be a more environmentally friendly material compared with normal concrete for structural elements.

Crumb Rubber and Silica Fume Inclusions in Pervious Concrete Pavement Systems: Evaluation of Hydrological, Functional, and Structural Properties

Abstract The main objective of this research study was to comprehensively investigate the hydrological, functional, and structural characteristics of 21 pervious concrete (PC) mixtures encompassing four dosages of crumb rubber (CR), four proportions of silica fume (SF) contents, and three distinct aggregate gradations. A total of 126 PC cylindrical specimens were available to measure density, porosity, permeability, abrasion resistance, and compressive strength properties. The inclusions of CR and SF in the PC enhanced the compressive strength and abrasion resistance compared to the control unmodified PC specimens. However, CR-modified PC showed reduced permeability because of a decrease in the porosity of those mixes. Nonetheless, the study results did not reach any optimum values of CR or SF replacement and indicated that there is more scope to replace the coarse aggregate with CR and cement with SF so as to identify the optimum dosages of these two modifiers in future. The use of CR in PC as a partial replacement of aggregate can become a potential way of conserving the natural aggregates that are becoming scarce. Furthermore, SF can be used as a partial replacement for cement that will eventually reduce carbon dioxide emissions from cement production, thus being able to achieve the significant use of renewable resources in producing green pavement systems.

A Study on the Prediction of Compressive Strength of M20 Grade Concrete using Reclaimed Rubber and Silica fume

A Study on the Prediction of Compressive Strength of M20 Grade Concrete using Reclaimed Rubber and Silica fume

Ventilation strategy for random pollutant releasing from rubber vulcanization process

This paper investigates the emission characteristic of a rubber vulcanization process in a workshop and tries to formulate a ventilation strategy for the rubber vulcanization production process with a lower exhaust rate. Measurements were performed to derive detailed source emission characteristic of rubber vulcanization process in a rubber workshop. The measurement results show that the primary source emission process was concentrated within 600 s of a vulcanization process, the corresponding cumulative emission percentage reached up to 95%. Based on random pollutant releasing from rubber vulcanization process, a single local exhaust hood was applied for a curing machine, the corresponding exhaust rate of 4000 m3/h was proven to be reliable for capturing rubber fume by the experimental and numerical methods. The corresponding cumulative capture efficiency of the single local exhaust hood was 92.1% at 600 s. A new ventilation system equipped with single local exhaust hood was further designed for the rubber vulcanization production process line, and the total exhaust rate of this system was only a quarter of the original one used in a large exhaust hood system. These findings have illustrated that the new ventilation system equipped with single local exhaust hood could largely reduce the exhaust rate in a rubber vulcanization workshop.

The Relations between Polycyclic Aromatic Hydrocarbons Exposure and 1-OHP Levels as a Biomarker of the Exposure.

Polycyclic aromatic hydrocarbons (PAHs) are the products of incomplete combustion or pyrolysis of various organic materials. Their ubiquity in the environment leads to measurable levels of exposure. However, the exposure varies strongly between different regions in Europe. Some PAHs with four or more rings are suspected to be human carcinogens. Therefore, the occupational and/or environmental exposure to PAHs may cause a significant health risk. The aim of the study was to evaluate current levels of PAH exposure in defined groups of workers. The industrial sites selected in this survey involved PAHs originating from coal tar pitch, carbon black, bitumen, and rubber fumes. Based on the historical data, the sites were expected to exhibit quantifiable levels of exposure to PAHs. The total study population consisted of 139 persons: 108 workers (85 males and 23 females) workers were occupationally exposed in aluminium production, the production of graphite electrodes, road construction, or the rubber forming industry and 31 control individuals in two groups. The highest concentrations – 8-hour time-weighted average (TWA) levels (sum of 16 components according to the EPA list), as expected, were found in the aluminium production plant (55.15 µg.m−3) and production of graphite electrodes (54.25 µg.m−3). The lowest concentrations were found in personal air samples of road construction workers (1.93 µg.m−3). The concentrations of 1-hydroxypyrene as a pyrene metabolite (1-OHP) in the urine of the exposed group of workers were found in levels 0.74 µmol.mol−1 creatinine before the exposure and 2.27 µmol.mol−1 creatinine after the exposure (arithmetic mean values). 1-OHP concentrations in post-shift urine samples were highly correlated with the total airborne PAHs concentrations and pyrene concentrations in air. The correlation coefficients (rS) between 1-OHP concentration and pyrene or total PAHs in air were 0.710 and 0.752 (p < 0.05). This statistical analysis confirmed the effect of the occupational exposure to PAHs and pyrene on body burden in workers. However, a modifying effect of gender, smoking habits, dietary intake, genetically modified metabolism, and the use of medication on the toxicokinetics of pyrene was not determined as significant. Based on the results a strong correlation between the concentration of 1-OHP in urine as an exposure biomarker and the concentration of pyrene or PAH was affirmed.