Tire shreds and tire shred  soil mixtures can be used as alternative backfill material in many geotechnical applications. The reuse of tire shreds may not only address growing environmental and ec...

/pdf/behaviour-of-tire-shred-sand-mixtures-2u9smxp58l.pdf

Behaviour of tire shred - sand mixtures

The growing interest in utilizing waste materials in civil engineering applications has opened the possibility of constructing reinforced soil structures with unconventional backfills. Scrap tires are a high-profile waste material for which several uses have been studied, including the use of shredded tires as backfill. A triaxial testing program was conducted to investigate the stress-strain relationship and strength of tire chips and a mixture of sand and tire chips. The test results and additional information from the literature were used in the numerical modeling of wall backfills, both unreinforced and reinforced with geosynthetics. The numerical modeling results suggest tire shreds, particularly when mixed with sand, may be effectively used as backfill.

Shredded Tires and Rubber-Sand as Lightweight Backfill

Waste tyres and their accumulation is a global environmental concern; they are not biodegradable, and, globally, an estimated 1.5 billion are generated annually. Waste tyres in landfill and stockpiles are renowned for leaching toxic chemicals into the surrounding environment, acting as breeding grounds for mosquitoes, and fuelling inextinguishable fires. The properties of waste tyre rubber and engineering applications have been previously reported in a range of publications with respect to the environmental, economic, and technical factors. This study compiles and reviews this research with a focus on geotechnical engineering applications, such as earthworks and infrastructure construction. The applications of waste rubber in construction materials includes cementitious concrete, asphalt concrete, and granular materials for earth structures. Crumb rubber, when used as a sand replacement in flowable concrete fill, improved ductility and strength-to-weight ratio. A 40 MPa concrete mix with 0.6% rubber crumb content exhibited optimal strength and air entrainment capabilities, displaying minimal damage after 56 freeze/thaw cycles. Rubber, as a partial replacement for aggregate in road base and sub-base layers, adversely affected the California Bearing Ratio (CBR) of the graded aggregate base course. Rubber-soil mixtures as the interface of foundation and structure yielded a 60–70 % reduction in vertical and horizontal ground accelerations when subjected to earthquake simulation modelling. There is concern regarding the toxicity of waste rubber incorporated products due to leachates of heavy metals and other chemicals common in tyres. Further comprehensive studies in this area are needed. Leachate studies should be conducted under different pH and liquid to solid ratios.

Recycling waste rubber tyres in construction materials and associated environmental considerations: A review

This paper proposes a promising seismic isolation method particularly suitable for developing countries, which makes use of rubber-soil mixtures. Apart from reducing the level of shaking in the horizontal direction, the distinctive advantage of the proposed method is that it can also significantly reduce the shaking level of vertical ground motion, to which an increasing attention has been paid in the earthquake engineering community. On the other hand, the use of scrap tires as the rubber material can provide an alternative way to consume the huge stockpile of scrap tires all over the world. Moreover, the low cost of this proposed seismic protection scheme can greatly benefit those developing countries where resources and technology are not adequate for earthquake mitigation with well-developed, yet expensive, techniques. The proposed method has been demonstrated through a series of numerical simulations and a parametric study has also been carried out. Lastly, five important issues regarding the concept and feasibility have been discussed.

Seismic isolation by rubber–soil mixtures for developing countries

The volume of scrap tires, an undesired urban waste, is increasing every year. One of the possible alternatives for this waste is to use shredded tires alone or mixed with soil as a lightweight bac...

Strength and deformation characteristics of shredded rubber tire - sand mixtures

Waste tires can be shredded (tire shreds) and re-used as fill material. The fill material may be comprised solely of tire shreds or mixed with sand (rubber-sand). If geosynthetics are to be used with fills containing tire shreds, it is necessary to understand the physical interaction between tire shreds, or rubber-sand, and the geosynthetic of interest. A laboratory testing program consisting of direct shear tests, interface direct shear tests, and geosynthetic pullout tests was conducted to determine the interaction properties of tire shreds and rubber-sand fills with three different flexible geogrids and a woven geotextile. Direct shear and interface direct shear tests were conducted using a large direct shear box with dimensions of 300 mm by 300 mm and a total depth of 230 mm. Pullout tests were carried out in a large pullout box with dimensions of 1.2 m in length by 0.9 m in width and a total depth of 0.5 m. The details of the testing program, the test results, and conclusions based on the test result...

Interaction Between Tire Shreds, Rubber-Sand and Geosynthetics

The results of a direct shear and pullout testing program conducted to evaluate the interaction properties of three types of flexible geogrids having 2 cm, 5 cm and 10 cm square apertures within two types of backfill materials are presented. The first backfill material was a 5 cm nominal size tire shred fill and the second backfill material was a rubber-sand mixture consisting of a blend of 5 cm tire shreds and sand. Direct shear testing was conducted using a large direct shear box having plan dimensions of 30 cm by 30 cm and a total depth of 23 cm. Pullout tests were carried out in a large pullout box having plan dimensions of 1.2 m in length by 0.9 m in width and 0.5 m depth. Coefficients of interaction between 0.22 to 0.49 for tire shreds and 0.25 to 0.53 for rubber-sand were calculated.

Pullout testing of geogrids in tire shreds and rubber-sand

Millions of scrap tires are discarded annually in the United States, the bulk of which are currently landfilled or stockpiled This consumes valuable landfill space, or, if improperly disposed, creates a fire hazard and provides a prolific breeding ground for rates and mosquitoes The use of tire shreds as lightweight fill material can sharply reduce the tire disposal problem The present study, based on laboratory testing and numerical modeling, examines the feasibility of incorporating tire shreds and rubber-sand mixtures as lightweight geomaterial in embankments and backfills

A. Bernal

Papers

Shredded Tires and Rubber-Sand as Lightweight Backfill

Interaction Between Tire Shreds, Rubber-Sand and Geosynthetics

Pullout testing of geogrids in tire shreds and rubber-sand

Laboratory study on the use of tire shreds and rubber-sand in backfills and reinforced soil applications. Final report