Dynamic Characterization of Tire Derived Aggregates (TDA) and its Application in Civil Engineering

Abstract

The substantial increase of scrap tires worldwide has resulted in the disposal of millions ‎of scrap ‎tires to stockpiles or landfills annually. These stockpiles raise a ‎significant risk to ‎the environment and human health, such as fire hazards, breeding ground for ‎insects, and ‎contaminating underground water. Therefore, reusing scrap tires has become an ‎important ‎necessity to reduce their impact on the environment and the public health.‎ Civil ‎engineering projects provide opportunities for the recycling of large volumes of waste ‎tires. Scrap tires are currently widely utilized in numerous civil engineering applications, ‎in the form of tire derived aggregates (TDA). This is due to the advantageous properties ‎of TDA, including high energy damping ability, low unit weight, and low cost. ‎Incorporating TDA in civil engineering projects is a safe, cost-effective approach to scrap ‎tire recycling. To safely integrate TDA in various civil engineering applications, the ‎material characterization and behavior should be fully investigated. Owing to the high ‎damping capacity and great linear elastic deformation of TDA, it could be used as a ‎geomaterial in seismic and vibration reduction applications.‎ In this dissertation, the dynamic response and characteristics of TDA is fully explored by ‎the means of large-scale cyclic triaxial, cyclic simple shear and bender element tests. ‎Furthermore, various important factors that could influence the behavior of TDA are also ‎investigated. These factors are consolidation pressure, shear strain, particle size, specimen ‎size, loading rate, number of cycles, effect of saturation, drainage condition, particle ‎orientation and hysteresis loop asymmetry. Due to the lack of the experimental data for ‎TDA in the literature, understanding the influence of these factors on the dynamic ‎response of TDA help to fill the knowledge gap in this area. Moreover, based on the ‎experimental data obtained form the conducted tests, shear modulus degradation model ‎for TDA is proposed. The proposed model along with the detailed investigation of the ‎dynamic characterization of TDA are of a paramount importance for practitioner ‎engineers in utilizing TDA in civil engineering applications associated with seismic ‎isolations and vibration mitigation.‎ Following the dynamic characterizing of TDA, the use of TDA in vibration reduction ‎applications was investigated experimentally. The performance of TDA trenches and ‎TDA buried trenches in mitigating sinusoidal vibrations were evaluated by conducting ‎full-scale tests. Numerous vibration tests were conducted in a steel tank with dimensions ‎of 2.75 m long, 2.25 m wide, and 1.80 m deep. The trench depth and the frequency of the ‎vibration source were varied from 0.2 to 0.6 m and 100 to 200 Hz, respectively. The ‎innovation aspects of this work include: (1) not only the frequencies are varied but also ‎different trench depths were considered, (2) the use of TDA as an infill material, (3) the ‎mitigation of the propagated vibrations in the X, Y and Z directions are investigated, and ‎‎(4) the performance of burying TDA trenches with two different soil covers was also ‎investigated.‎ Finally, 2D plain-strain Plaxis model was developed to provide more insights on the ‎various parameters that affect the performance of buried trenches which are used to ‎mitigated the propagating vibrations from a machine foundation.‎