Crumb Rubber Content Research Articles

Effects of Crumb Rubber on Compressive Strength of Cement-Treated Soil

A study was undertaken to investigate the effects of crumb rubber on the strength and mechanical behaviour of Rubberized cement soil (RCS). In the present investigation, 26 groups of soil samples were prepared at five different percentages of crumb rubber content, four different percentages of cement content and two different finenesses of crumb rubber particle. Compressive strength tests were carried out at the curing age of 7 days, 14 days, 28 days and 90 days. The test results indicated that the inclusion of crumb rubber within cement soil leads to a decrease in the compressive strength and stiffness and improves the cement soil’s brittle behaviour to a more ductile one. A reduction of up to 31% in the compressive strength happened in the 20% crumb content group. The compressive strength increases with the increase in the cement content. And the enlargement of cement content is more efficient at low cement content.

Dynamic mechanical behaviour of recycled crumb rubber concrete materials subjected to repeated impact

An experimental investigation was conducted on the dynamic mechanical behaviour of crumb rubber concrete materials with crumb rubber contents varying from 0% to 20% (equal volume of fine aggregate replacement) subjected to repeated impacts using a split-Hopkinson pressure bar. The influence of the rubber content on the dynamic properties of crumb rubber concrete, subjected to repeated impacts, was explored. The test results show that the impact resistance time of crumb rubber concrete increases with lower rubber content and then decreases with higher content. Moreover, the static compressive strength of crumb rubber concrete decreases with the increase of rubber content. The capability of energy absorption of crumb rubber concrete under impact loading is higher than that of normal concrete. The incorporation of rubber enhanced the toughness of crumb rubber concrete significantly and the impact resistance of crumb rubber concrete is greatly increased.

Influence of Crumb Rubber on Impact Energy of Steel Fiber Concrete Beams

This paper presents the impact energy of steel fiber concrete beams at first crack and failure with different replacement ratios of crumb rubber. The test was carried out using simple low velocity drop weight test rig for both normal concrete (NC) and steel fiber concrete (SFC). The crumb rubber with particle size of 1 – 2 mm was added with replacement ratios of 5%, 15%, and 25% by volume of fine aggregate. Six batches consisting of 6 beams (100x100x500 mm) containing 0.5% of hooked end steel fibers were tested under impact load in accordance with ACI Committee 544. The specimens were tested at the age 90 days after curing in water. The results show a reduction in the compressive strength for both NC and SFC with the incorporation of crumb rubber with greater reduction at higher crumb rubber content. However, the measured impact energy for both NC and SFC was foundincreasing with the crumb rubber replacement.

Strength, durability, and environmental properties of concrete utilizing recycled tire particles for pavement applications

The Rubber Manufacturers Association reported that approximately 230.7million tires were disposed in the United States in 2011. Over 197.5million of these disposed tires are recycled as tire derived fuel, lightweight fill, retaining walls, erosion protection as well as many other marketable uses. The primary objective of this study was to examine an alternative use for the 33.2million remaining waste tires land disposed throughout the United States. This study used recycled tires in the form of crumb rubber as a fine aggregate replacement in concrete mixtures. Sustainable concrete mixtures for pavement applications that incorporated waste-stream materials such as fly ash, crumb rubber, and recycled concrete aggregate were evaluated for their performance. Fresh and hardened concrete properties were measured on mixtures containing 15% cement replacement with fly ash and sand volume replacements with crumb rubber of 10%, 20%, 30%, 40%, and 50%. The effects of the crumb rubber inclusion were determined by comparing mixtures containing the crumb rubber to a control mixture with only sand as the fine aggregate. Recycled concrete aggregate was included as a 50% coarse aggregate replacement by volume in two mixtures containing 20% and 30% crumb rubber content. The mixtures were tested for fresh concrete properties including slump, air content, unit weight and temperature, and hardened concrete properties including compressive strength, split-tensile strength, modulus of rupture, modulus of elasticity, permeability, and freeze–thaw durability. In addition, tests were conducted to determine whether any volatile organics leached from the crumb rubber concrete. As the crumb rubber content increased, the compressive strength, split-tensile, modulus of rupture, and the modulus of elasticity decreased. The crumb rubber concrete’s permeability increased within acceptable levels up to a 40% replacement of sand. The results of this study determined that a 30% replacement of sand with crumb rubber (approximately 5.5% of the total mixture volume) was optimum and produced the necessary fresh and hardened properties for concrete pavement.

Olefin–maleic-anhydride copolymer based additives: A novel approach for compatibilizing blends of waste polyethylene and crumb rubber

In our work processing conditions and mechanical properties of waste polyethylene (PE)/crumb rubber (CR) blends have been improved by new types of compatibilizing additives synthesized from experimental olefin–maleic-anhydride copolymers at our laboratory.Compatibilizing additives have been introduced into the PE/CR blends in 0.2wt% while CR concentration has been varied between 10 and 50wt%. For comparison of the effects commercially available MA-g-PO type compatibilizing additives have also been applied. Tensile and Charpy impact tests of the compression moulded samples have been carried out.Several experimental additives have enhanced properties of the PE/CR blends either from the point of view of tensile or Charpy impact strength while commercial additives have had improving effects only on one of the abovementioned mechanical properties but not for both of them simultaneously. Since good mechanical properties could be achieved by our experimental compatibilizers good adhesion in the waste PE/CR samples have been considered and was proven by SEM graphs either.

Compressive and flexural behaviours of a new steel-fibre-reinforced recycled aggregate concrete with crumb rubber

Using recycled concrete and crumb rubber as aggregates to produce green concrete is a promising technology toward sustainability in the construction industry. In this study, the compressive and flexural behaviours of a new type of concrete material, rubber crumb and steel-fibre-reinforced recycled aggregate concrete (RSRAC), are investigated. To popularise the application of this new type of green building material, an experimental study was conducted to investigate the effect of the rubber content on the compressive and flexural behaviours of RSRAC. A total of 18 cubes (150mm) and 18 cylinders (150mm×200mm) were tested under axial compressive loading, and 18 prisms of 150×150×550mm were tested subjected to three-point bending. The crumb rubber content was varied in the investigation at levels of 0%, 4%, 8%, 12% and 16% by volume substitution of sand. Recycled concrete aggregate (RCA) was introduced into the concrete mixture by 100% volume substitution of natural coarse aggregate (NCA), and 1% volumetric quantity of steel fibre was added to the concrete mixture. The effect of the rubber content on the compressive and flexural strength, failure mode, modulus of elasticity and toughness of RSRAC was analysed. The results indicate that RSRAC with an optimal rubber content displays good compressive behaviour compared with normal NCA concrete. RSRAC is also a more environmentally friendly alternative to normal rubber concrete for use in theflexural members of concrete structures.

Structural performance of dry-cast rubberized concrete pipes with steel and synthetic fibers

A study was conducted to address the enhancement of the structural performance of concrete pipes through the use of crumb rubber, steel, and synthetic (polypropylene) fibers. Based on the three-edge bearing (3EB) test according to ASTM standard C497, pipes with five different dry-cast concrete mixtures were produced and tested: (1) reinforced concrete pipe (RCP), (2) crumb rubberized concrete pipe (CRP), (3 and 4) steel or polypropylene fiber reinforced rubberized concrete pipe (SFP or PFP), and (5) hybrid fiber reinforced rubberized concrete pipe (HYP). This study investigates how the variation of the fiber volume fraction and crumb rubber content in the dry cast concrete mix affects the behavior of pipes with diameters of 600mm (24in.) and 900mm (36in.). The crumb rubber particles replaced from 3% to 20% (by volume) of fine aggregate in the mixture used for concrete pipes. A series of rubberized concrete mixes were employed with a variation in the fiber volume fraction (Vf) (steel: 0.17% and 0.33%, polypropylene: 0.13%, 0.33%, 0.52% and 0.65%). Thirty-one rubberized concrete pipes were developed by incorporating different dosages of steel and polypropylene fibers and their combinations. Test results revealed that hybrid fiber reinforcements (both steel and polypropylene fibers) were more effective than single type fiber reinforcement (steel or polypropylene fibers) in enhancing the rubberized concrete pipe strength and ductility. In order to reach the strength requirement for Class III (96kN/m/m) and Class II (72kN/m/m) according to ASTM C76, fine aggregates can be replaced with an equal volume of crumb rubber up to 3% and 5% in HYPs, respectively, for the rubberized concrete pipes produced with zero-slump concrete.

Strength reduction factors for structural rubbercrete

Many researches have been carried out to study the fresh and hardened properties of concrete containing crumb rubber as replacement to fine aggregate by volume, yet there is no specific guideline has been developed on the mix design of the rubbercrete. The experimental program, which has been developed and reported in this paper, is designed and executed to provide such mix design guidelines. A total of 45 concrete mixes with three different water to cement ratio (0.41, 0.57 and 0.68) were cast and tested for fresh and mechanical properties of rubbercrete such as slump, air content, unit weight, compressive strength, flexural strength, splitting tensile strength and modulus of elasticity. Influence of mix design parameters such as percentage of crumb rubber replacement, cement content, water content, fine aggregate content, and coarse aggregate content were investigated. Three levels of slump value (for conventional concrete mixes) has been selected; low, medium and high slump. In each slump level, water content was kept constant. Equations for the reduction factors (RFs) for compressive strength, flexural strength, splitting tensile strength and modulus of elasticity have been developed. These RFs can be used to design rubbercrete mixes based on the conventional mix (0% crumb rubber content)

Proposed Compaction Procedure for Dry Process Crumb Rubber Modified Asphalt Mixtures Using Air Void Content and Expansion Ratio

The dry process for crumb rubber modified (CRM) asphalt mixtures is characterized by a simple construction process that results in greater environmental benefits than the wet process does. However, the difficulties of compaction in the dry process often lead to unstable pavement performance; therefore, its application is highly restricted. This research aims to investigate the compaction procedure for dry process CRM asphalt mixtures using air void content and expansion ratio as the principal indices for evaluation. To evaluate the key factors affecting compaction, a series of CRM mixtures were prepared and compacted at four different crumb rubber contents by total aggregate volume of 3.0 %, 5.5 %, 8.0 %, and 10 %. First, with the air void ratio as the target indicator, the crumb rubber content, compaction temperature, and compaction method were evaluated to determine the appropriate compaction procedure. Second, the variations in height and expansion ratio of the CRM asphalt mixture specimens with different crumb rubber contents were analyzed in order to calculate the expansion ratio. The results indicated that generally the height and expansion ratio increase as the crumb rubber content of the CRM asphalt mixtures increases. Furthermore, it was found that when the crumb rubber addition was 5.5 % of the bulk volume of minerals, the volume stability of the mixture was improved, and this value is recommended for dry process CRM asphalt mixtures.

STUDY OF A ROAD TEST TRACK WITH AND WITHOUT CRUMB RUBBER. SOLUTIONS FOR NOISE POLLUTION

End-of-life tires are waste materials that pollute landscapes when they are disposed of in tire dumps. However, its life cycle is not finished when they are scrapped. The rubber of end-of-life tires could be used for new purposes as construction material in road rehabilitation. A gap-graded mix characterization was carried out in this work by means of laboratory and field performance tests. The mixture has a high content of crumb rubber (CR) by weight of bitumen. Crumb Rubber was added to the binder by a wet process. Close proximity methodology has been used in in-situ characterization of the acoustic behaviour. Moreover, absorption and dynamic stiffness tests were also conducted to determine the noise generation mechanisms involved in noise. According to the results achieved, a reduction of the noise emitted by the tire/pavement interaction could be accomplished with the construction of roads with mixture with CR added by a wet process. In addition, this would result in a decrease of the amount of waste tires in landfills.

Effect of Shear Time and the Crumb Rubber Percentage on the Properties of Composite Modified Asphalt

This paper presents a laboratory study of Styrene-Butadiene-Styrene (SBS)/ crumb rubber modified asphalt by the two-step method. The conventional properties of the modified asphalt were determined. The effects of crumb rubber content and shearing time on the performance of the crumb rubber modified asphalt and composite modified asphalt. The results show that the crumb rubber contents and shearing time have significant impacts on the performance of the modified asphalt. With the crumb rubber content increasing, the high temperature performance was improved and the low temperature chanethe softening point increases and penetration decrease, and the ductility change little. It is comfortable for workability at the crumb rubber content of 20%. The viscosity is an important measurement for the workability of the modified asphalt. After adding the stabilizer, the viscosity increases until the shearing time reaching 1.5h, then it will decrease gradually.

삼축압축시험에 의한 폐어망 보강 저회-폐타이어 혼합토의 전단특성

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.

Experimental Study on Mechanical Properties of Recycled Asphalt Mixture with Different Proportion of Rubber Powder

Through a series of mechanical properties experiment of recycled asphalt mixture composed of waste asphalt mixture 20% and different content of rubber powder, the paper analyzes and compares the elasticity, tensile strength and bending strength of asphalt mixture and recycled asphalt mixture, concluding that recycled asphalt mixture that mixed with crumb rubber content of 20% can completely replace the new asphalt mixture in the application. It has great significance for the future to recycling waste asphalt mixture in the highway.

Crumb Rubber (CR) as an Alternative Binder to Supplement Bitumen: Nigeria as a Case Study

This research investigated the suitability of Crumb Rubber (CR) as an alternative binder to supplement bitumen. The emerging trends in the world has challenged researchers to seek means of converting waste to wealth partly because of the environmental concerns they pose and partly because there is a general dearth of raw materials as the stock of the existing ones are fast depleting. In this research, the traditional Marshall Test method was arbitrary used to test 20%, 40%, and 60% CR proportions replacement of bitumen against the control (0% CR). The results were assessed based on the provisions of Asphalt Institute Marshall Criteria to determine the conformity with engineering properties-Stability, Flow, and Void analysis. The results indicated that 40% CR content resulting in Stability - 11.0KN, Flow - 4.3mm and VIM-14.45% trailed those with content 0% CR, but adequate in engineering properties to replace bitumen in asphalt mix. The results meet the criteria of medium class traffic specified by Asphalt Institute (1979).

Road pavement rehabilitation using a binder with a high content of crumb rubber: Influence on noise reduction

Although performance of pavements depend on the characteristics of materials used, design accuracy and construction quality, crumb rubber modified binders (CRMB) are materials with an increasing use in road pavements due to their enhanced properties and to the environmental protection by re-using a waste material. This paper presents the laboratory characterization and the evaluation of field performances of a gap-graded mix with 20% of crumb rubber by weight of bitumen, added by a wet process. Acoustical field characterization has been performed by determining, at different speeds, sound levels and noise spectra measured in close proximity. Road profiles along the test sections and sound absorption of compacted sample cores also have been studied to analyze their relationship with the noise emitted. Results show that the use of a binder modified with a high content of crumb rubber reduces the noise emitted by the tyre/pavement interaction.

Effects of Crumb Rubber Size and Concentration on Performance of Porous Asphalt Mixtures

The purpose of this study is to investigate the effect of size distribution and concentration of crumb rubber on the performance characteristics of porous asphalt mixture. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps. Firstly, the mixture design was performed to determine the optimum bitumen content. In the latter step, the mixtures were modified by dry process using crumb rubber in three different grain size distributions of #4~#20, #20~#200, and #4~#200 and rubber content of 10%, 15%, and 20% as weight of optimum bitumen. The permeability, Cantabro abrasion loss, indirect tensile strength, moisture susceptibility, and resilient modulus tests were carried out on the specimens. Test results show that #20~#200 sized rubber particles reduced air voids and coefficient of permeability, while they increased the Cantabro abrasion loss. In general, increasing the crumb rubber size and content decreased the performance characteristics of the porous asphalt mixtures.

Investigations of Physical and Rheological Properties of Aged Rubberised Bitumen

Several road pavement distresses are related to rheological bitumen properties. Rutting and fatigue cracking are the major distresses that lead to permanent failures in pavement construction. Influence of crumb rubber modifier (CRM) on rheological properties of bitumen binder such as improvement of high and intermediate temperatures is investigated in the binder’s fatigue and rutting resistance through physical-rheological changes in this research. The bitumen binders were aged by rolling thin film oven (RTFOT) to simulate short-term aging and pressure aging vessel (PAV) to simulate long-term aging. The effects of aging on the rheological and physical properties of bitumen binders were studied conducting dynamic shear rheometer test (DSR), Brookfield viscometer test, softening point test, and penetration test. The results showed that the use of rubberised bitumen binder reduces the aging effect on physical and rheological properties of the bitumen binder as illustrated through lower aging index of viscosity, lower aging index of , and an increase in with crumb rubber modifier content increasing, indicating that the crumb rubber might improve the aging resistance of rubberised bitumen binder. In addition, the results showed that the softening point increment () and penetration aging ratio (PAR) of the rubberised bitumen binder decreased significantly due to crumb rubber modification. Furthermore, the higher crumb rubber content, the lower after PAV aging, which led to higher resistance to fatigue cracking bitumen.

Analysis of the Low-Temperature Rheological Properties of Rubberized Warm Mix Asphalt Binders

Abstract Warm mix asphalt (WMA) has generated a lot of interest worldwide based on the potential to realize environmental benefits related to lower production temperature and safe disposal of crumb rubber (tires). However, barriers to complete implementation of WMA technology still exist because of the lack of understanding of how different additives affect the performance of crumb rubber modified (CRM) binders. This paper investigates the effects of three WMA additives and crumb rubber concentration on the low-temperature performance of the CRM binders. The WMA additives used in this study were Sasobit, RH, and Advera, and the ambient 40 mesh tire rubber at different concentrations of 10 %, 15 %, 20 %, and 25 % by the weight of asphalt binder were applied in this paper. Burgers model was used to describe the relationship between deformation and time for rubberized WMA binder. The models parameters such as relaxation time, delay time, creep stiffness, m-value and m/S(t)-ratio were applied to evaluate the low-temperature performance of the rubberized WMA binders. Furthermore, the statistical analysis of variance (ANOVA) technique was applied to quantify the effects of different WMA additives and crumb rubber concentrations on the rubberized asphalt binders’ low-temperature performance. It was found that Advera could be used to enhance the low-temperature performance by enhancing the stress relaxation, whereas RH and Sasobit did not exhibit this ability, thereby weakening the low-temperature performance of the CRM binders. The crumb rubber concentration could significantly increase the rubberized WMA binders’ low-temperature performance by influencing the flexural creep stiffness of the control binders.

Investigating the rheological properties of crumb rubber modified bitumen and its correlation with temperature susceptibility

There is substantial evidence on the advantages of using crumb rubber in enhancing conventional bitumen properties, gaining environmental protection and boosting industrial-economical benefits. Thus, the use of this ingenious additive in bitumen modification through sustainable technology is highly advocated.The main objective of this research is to investigate the effects of different blending conditions (of time and temperature) and various crumb rubber contents on the properties of bitumen binders. Testing was conducted using the Dynamic shear rheometer (DSR) test and softening point test. The results showed that differing crumb rubber content

A Study on the Influences of Crumb Rubber Modified Asphalt

In order to study the effects of different factors on the performance of crumb rubber modified asphalt, on the basis of many laboratory tests, this article analyzed such factors as types of crumb rubber, fineness, content, mixing temperature and matrix asphalt. Results show that mixed with the crumb rubber, pavement performance of the asphalt has been improved to varying degree. In the engineering application of rubber asphalt, it is suggested that the 20 mesh crumb rubber modified asphalt of truck tire be adopted, with about 16% to 18% of crumb rubber content at about 175°C. As for matrix asphalt, it should be selected according to the different climatic conditions and the mechanical characteristics of the pavement.