• Computers and Concrete
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• v.29 no.1
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• pp.47-57
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• 2022

The increase in waste tires has brought serious environmental problems. Using waste tires rubber particles as aggregate in concrete can reduce pollution and decrease the usage of natural aggregate. The paper describes an investigation on flexural bearing capacity of self-compacting concrete (SCC) pavement slabs containing crumb rubber. Cyclic loading tests with different stress ratios and loading frequencies are carried out on SCC pavement slabs containing crumb rubber. Based on Paris Law and test data, the fatigue life of SCC pavement slab containing crumb rubber is discussed, and a revised mathematical model is established to predict the fatigue life of SCC pavement slab containing crumb rubber. The model applies to different stress ratios and loading frequencies. The fatigue life of SCC pavement slab containing crumb rubber is affected by the stress ratio and loading frequency. The fatigue life increases with the increase of stress ratio and loading frequency. Real-time acoustic emission (AE) signals in the SCC pavement slab containing crumb rubber under cyclic loading are measured, and the characteristics of crack propagation in the SCC pavement slab containing crumb rubber under different stress ratios and loading frequencies are compared. The AE signals provide abundant information of fracture process zone and crack propagation. The variation of AE ringing count, energy and b-value show that the fracture process of SCC pavement slab containing crumb rubber is divided into three stages.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.163-172
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• 1996

Recently, the disposal of used vehicle tires is a big social problem because the amount of used vehicle tires has been increased with development of' automobile industry. Many researches have been made on the recycling of used vehicle tires in the various fields of industry as well as construction industry. When the crumb rubber made of vehicle tires is mixed in cement concrete and mortar, it is indicated that the adhesive strength of interface between the crumb rubber and cement hydrates is very low. The purpose of this study is to improve the fundamental properties by increasing of the adhesion strength of styrene-butadiene rubber(SF3R) latex coated crumb rubber in ; cement mortar. SBR-modified mortar using crumb rubber is also tested as the same method. From the test results, the cement mortar using SBR latex coated crumb rubber have a good fundamental properties compared with that using uncoated crumb rubber. The mechanical properties of SBR-modified mortar using crumb rubber with polymer-cement ratios of 10% are also improved.

• Computers and Concrete
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• v.20 no.3
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• pp.311-318
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• 2017

This paper investigates the utilization of waste tyre crumb rubber as the fine aggregate in precast concrete Paving block (PCPB). PCPB's are generally preferred for city roads, pedestrian crosswalk, parking lots and bus terminals. The main aim of this paper is to evaluate the mechanical properties of wet cast PCPB containing waste tyre crumb rubber. The mechanical properties were investigated using a density, compressive strength, split tensile strength and flexural strength tests at 7, 28 56 days according to the IS 15688:2006 and EN1338. The wet cast method was followed for producing PCPB samples. The fine aggregate (river sand) was replaced with waste tyre crumb in percentage of 5%, 10%, 15%, 20% and 25% by volume. All the test results were compared with the conventional PCPB (Without rubber). The test results indicate its feasibility for incorporating waste tyre crumb rubber in the production of PCPB by the wet cast method.

• Journal of the Korean Geotechnical Society
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• v.29 no.9
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• pp.81-91
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• 2013

This paper investigates the shear properties of bottom ash-crumb rubber mixture reinforced with waste fishing net. Mixtures used in this experiment were prepared at 2 different percentages of crumb rubber (2 mm~10 mm) content (i.e., 0%, 50% by weight of the dry bottom ash). In this study several series of triaxial tests were carried out on the six different specimens : unreinforced bottom ash, reinforced bottom ash with 1 or 2 layers, unreinforced mixture, reinforced mixture with 1 or 2 layers. The experimental results indicated that the shear properties of bottom ash-crumb rubber mixture were strongly influenced by reinforcing layer of waste fishing net and crumb rubber addition. It is shown that the internal friction angle of bottom ash-crumb rubber mixture decrease with addition of crumb rubber due to the compression properties of crumb rubber. However, the internal friction angle of the mixture increased with an increase in reinforcing layer due to interlocking effect and friction between mixture and waste fishing net.

• Advances in concrete construction
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• v.9 no.3
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• pp.249-256
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• 2020

This paper aims at investigating the effect of crumb rubber size and content on compressive behaviors of concrete under axial compression. Concrete specimens are designed and produced by replacing natural aggregate with crumb rubber content of 0%, 5%, 10%, 15% and three different sized crumb rubbers (No. 20, No. 40, No. 80 crumb rubber). And the failure mode, compressive strength, elastic modulus, stress-strain curves, peak strain and ultimate strain are experimentally studied. Based on the test results, formulas have been presented to determine the compressive strength, elastic modulus, the relationship between prism compressive strength and cube compressive strength, stress-strain curves and peak strain of crumb rubber concrete (CRC). It is found that the proposed formulas agree well with the test result on the whole, which may be used to practical applications.

• Environmental Analysis Health and Toxicology
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• v.27
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• pp.5.1-5.10
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• 2012

Objectives: The purpose of this study was to assess the risk of ingestion exposure of lead by particle sizes of crumb rubber in artificial turf filling material with consideration of bioavailability. Methods: This study estimated the ingestion exposure by particle sizes (more than 250 um or less than 250 um) focusing on recyclable ethylene propylene diene monomer crumb rubber being used as artificial turf filling. Analysis on crumb rubber was conducted using body ingestion exposure estimate method in which total content test method, acid extraction method and digestion extraction method are reflected. Bioavailability which is a calibrating factor was reflected in ingestion exposure estimate method and applied in exposure assessment and risk assessment. Two methods using acid extraction and digestion extraction concentration were compared and evaluated. Results: As a result of the ingestion exposure of crumb rubber material, the average lead exposure amount to the digestion extraction result among crumb rubber was calculated to be $1.56{\times}10^{-4}$ mg/kg-day for low grade elementary school students and $4.87{\times}10^{-5}$ mg/kg-day for middle and high school students in 250 um or less particle size, and that to the acid extraction result was higher than the digestion extraction result. Results of digestion extraction and acid extraction showed that the hazard quotient was estimated by about over 2 times more in particle size of lower than 250 um than in higher than 250 um. There was a case of an elementary school student in which the hazard quotient exceeded 0.1. Conclusions: Results of this study confirm that the exposure of lead ingestion and risk level increases as the particle size of crumb rubber gets smaller.

• Geomechanics and Engineering
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• v.36 no.1
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• pp.39-50
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• 2024

Bitumen and high-quality subangular aggregates, the two principal materials used for asphalt concrete construction, are finite and expensive materials. The general availability of crumb rubber and naturally occurring aggregates of different shapes, especially flat and elongated shapes, indicates that they are feasible alternative materials for expanding the volume of bitumen and utilizing a wider range of aggregate shapes for the development of asphalt concrete, with an associated environmental benefit. The study investigated the effect of adding up to 15% crumb rubber and aggregates sorted into different groups, i.e., rounded, elongated, flat, and their combinations, on the rheological and mechanical properties and durability of 50/70 of hot-mix asphalt pavement. The addition of crumb rubber decreased ductility and penetration but increased the softening point. For a 5.5% bitumen content, asphalt concrete briquettes consisting of 7% crumb rubber and three types of aggregate shapes, i.e., 100% rounded, a mix of 75% rounded and 25% elongated, and a mix of 75% rounded, 15% elongated and 10% flat, were associated with high Marshall stability and indirect tensile strength as well as low lateral deformation due to their high solidity and moderate angularity ratio. Also, the addition of 7% crumb rubber resulted in a significant improvement in the tensile strength ratio and rebound strain of briquettes consisting of 75% rounded and 25% elongated aggregates and those with 75% rounded, 15% elongated and 10% flat aggregates. In relation to the parameters investigated, the three groups of briquettes met some of the local (South Africa) requirements for the surface course and base course of low traffic volume roads.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.83-91
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• 2006

This research was initiated to enhance the tilth of fine-textured soil for turf growth by incorporation of crumb rubber shredded from used tires. A specific objective was to determine the physical properties of soil mixes amended with different grade and amount of crumb rubber in soils. Two soils and three different grades(3.5, 6.5 and 9.5 mm) of crumb rubber were used. The soils selected were an Arenzville silt loam(coarse-silty, mixed, nonacid, mesic Typic Udifluvents) and a Hosmer silty clay loam(fine-silty, mixed, mesic Typic Fragiudalfs). The amount of crumb rubber mixed in soil ranged from 0 to 0.4 $g{\cdot}g^{-1}$(using 0.05 $g{\cdot}g^{-1}$) increments and 0 as a control. For each treatment, soil cores were constructed following the recommendation by the United States Golf Association Green Section Record. Results indicated that porosity of the mixes decreased as the amount of crumb rubber increased. Regardless of the grade of crumb rubber, mixes with less than 0.15 $g{\cdot}g^{-1}$ of crumb rubber in fine-textured soil could not enhance their macro-porosity and hydraulic conductivity. However, as the amendment increased over 0.15 $g{\cdot}g^{-1}$, the tilth of the mixes had improved significantly macro-porosity, hydraulic conductivity and air permeability, as compared with a control.

• International Journal of Highway Engineering
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• v.11 no.3
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• pp.33-40
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• 2009

The use of the crumb rubber as an asphalt binder modifier may contribute to road maintenance and repair. The adhesion properties of the crumb rubber modified asphalt (CRMA) sealant have attracted interest due to brittle and adhesion failure of asphalt binders at low temperatures. In this study, the influence of a flexibilizer as a modifier for CRMA at low temperatures was investigated. Their properties were measured using the penetration, the softening point, the tensile and tensile adhesion tests at low temperature. The tensile adhesion strength and the strain of CRMAs were increased with increasing ductile deformation of the CR and the asphalt binder in the flexiblizer modified CRMAs. It was found that the flexibilizer concentration was an important factor for tensile and adhesion properties of CRMAs at low temperatures.

• Computers and Concrete
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• v.25 no.3
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• pp.267-272
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• 2020

This paper investigates the effect of crumb rubber (CR) on compressive behaviour of crumb rubber concrete filled steel tube (CRCFST) stub columns. Therefore, experiments on 16 stub columns subjected to axial loading are carried out. The results show that the failure modes of CRCFST stub columns with different CR replacement ratios and CR size are similar, manifested the buckling of the outer steel tube. The axial bearing capacity and stiffness both decrease with an increase in CR replacement ratio, and with decreasing CR size.