https://orcid.org/0000-0002-2166-5111
Abstract
Laboratory testing of a mass of large-particle-sized tire derived aggregate (TDA) to assess performance-related properties such as void ratio, compressive creep, and hydraulic conductivity under large loads poses a number of experimental challenges. Large-particle-sized TDA is shredded scrap tires with particle sizes from 50 mm to over 305 mm. The large particle size of the TDA mass results in experimental challenges, such as the need for a large test chamber and the need for a load application system with a capacity to apply and sustain large loads, while accommodating large vertical displacements from the compression of the TDA mass. As an example, to put these requirements into perspective, a mass of TDA with a nominal particle size of 150 mm requires a test cell diameter of at least 600 mm and preferably a diameter of 700 mm. If a load of 400 kPa were to be applied onto the TDA mass to simulate approximately 35 m to 40 m of overlying material (waste and routinely applied cover materials) in an application such as a landfill, the test apparatus must be capable of delivering over 150 kN of applied load. Furthermore, for a reasonable initial mass of TDA that is 1.2 m thick, the test cell will have to be designed to maintain that load over 0.6 m of vertical displacement because of the compression of the TDA mass. This article presents a number of practical strategies that were implemented to overcome the experimental challenges with testing large particle size, highly compressible TDA mass to establish the performance related properties for use in service. In some instances, components of the test equipment had to be re-engineered to accommodate exigencies that had not been anticipated, such as differential compression of the TDA mass. The focus of this article is on equipment design and experimental methodologies. A few sample results from the study are presented to illustrate the successful implementation of the design methodologies. Although TDA has been studied in this work, the strategies described herein can be applied to a wide range of highly compressible materials under large loads.
