Properties of tire derived aggregate for engineering applications

Graduation Date

2013

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Environmental Systems: Environmental Resources Engineering, 2013

Committee Chair Name

Brad A. Finney

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Chemical leachate analysis from simulated septic leach lines, Type B tire derived aggregate, Tire derived aggregate, Type A tire derived aggregate, TDA, Humboldt State University -- Projects -- Environmental Resources Engineering

Abstract

Disposal costs of scrap tires have prompted researchers to investigate beneficial reuses for waste tires. One important application is use of tire chips as tire derived aggregate (TDA), which can be a substitute for rock aggregate in engineering applications. Properties of TDA were investigated through a series of experiments using type A TDA (maximum 8-in. length), type B TDA (maximum 12-in. length) and a 50/50 mixture of type A and type B TDA. Three areas of testing were completed on TDA, which included physical properties, substitution of rock aggregate with TDA in leach fields, and exothermic properties of TDA. A small and large magnitude dynamic vertical compression test was completed using tri-axial cylinders to measure the compressibility of TDA. Density, weight specific gravity, void ratio, and porosity were also calculated during experimental tests. During compression testing, TDA initially exhibited plastic compression under load, but after TDA was subjected to compressive loads it behaved like an elastic material. A constant-head permeameter, under loads up to 95 pounds per square inch, was used to measure the hydraulic conductivity of TDA. The hydraulic conductivity varied for all tests by TDA type (type A or B or a 50/50 mixture), applied pressure, and hydraulic gradient. Implications of substituting TDA for rock in leach fields were also investigated. Results indicated that TDA was a viable substitute for rock aggregate in septic systems with regards to wastewater treatment and durability. A leach field that contained TDA showed increased microbiological growth within the media and statistically significant effluent quality for eight constituents (of 84 tested constituents) when compared to a leach field containing rock aggregate that was under equivalent wastewater loading conditions. A thermal analysis of temperature changesover time was also completed using clean (did not have flammable liquids on the material) type A TDA in (1) a septic leach field, (2) a 20 ft. tall column of packed TDA, and (3) an underground earthen pit, where TDA was placed in the ground within 12 hours of manufacturing. In all thermal experiments, clean type A TDA did not show any hazardous reactions that would cause fire concerns.

https://scholarworks.calstate.edu/concern/theses/6w924f067

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