Scrap Tire Derived Geomaterials - Opportunities and Challenges

Proceedings of the International Workshop IW-TDGM 2007 (Yokosuka, Japan, 23-24 March 2007)

Hemanta Hazarika, Kazuya Yasuhara

• Publisher: CRC Press
• Year: 2007
• Print ISBN: 9780415460705
• eBook ISBN: 9781134044627
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

SCRAP TIRE DERIVED GEOMATERIALS is a compilation of peer-reviewed papers presented at the International Workshop on Scrap Tire Derived Geomaterials (IW-TDGM 2007) in Yokosuka, Japan in March 2007.The workshop was the first ever international forum on scrap tire derived geomaterials (TDGM), bringing together people from various disciplines working i

Technical papers

Part 1 Mechanical properties, modeling and novel applications

Scrap Tire Derived Geomaterials – Opportunities and Challenges – Hazarika & Yasuhara (eds)
© 2008 Taylor & Francis Group, London, ISBN 978-0-415-46070-5

Size effect on tire derived aggregate mechanical properties

M. Arroyo, J. Estaire,¹ I. Sanmartin & A. Lloret
Department of Geotechnical Engineering and Geosciences, UPC, Barcelona, Spain ¹Laboratorio de Geotecnia, CEDEX, Madrid, Spain

ABSTRACT: Tire derived aggregate might substitute for other granular materials in civil engineering structures. Processing the tires to obtain granulate materials has a cost that increases rapidly as the aggregate size decreases; this reason favors the use of large aggregate sizes. Minimizing the risk of self-combustion is another reason why large aggregate sizes are favored in civil engineering applications. The use of relatively large aggregate sizes (30 to 3 cm) poses a characterization problem. Geotechnical test equipment is classically designed to deal with smaller granulate sizes. Tire derived aggregates of smaller sizes are available and may be employed as an analogue, but the doubt remains about the validity of the properties thus derived for the larger aggregate sizes employed in civil engineering structures. A testing program has been designed to explore possible size effects in shear resistance and compressibility of tire derived aggregates. This communication presents some results of that testing program, with an emphasis on shear resistance.

1 INTRODUCTION

During the last decade disposal of used tires has been a subject of major regulatory activity in Europe in general and Spain in particular. The EU Landfill Directive (EU, 1999) forbade the landfill disposal of whole tires since 2003 and of shredded tires since 2006. In 2001 Spain Environment ministry presented the first national plan on waste tire (PNNFU, MMA 2001). A hierarchy of waste management strategies was established: prevention, re-use, recycle, energy production and disposal, in order of priority. The plan established a goal of 20% of total waste tire production recycled by 2006.

The last available statistics (MMA, 2007) indicate that currently about 300,000 tons of waste tires are generated per year in Spain. In 2005 (last year for which data is available) only 13,5% of the total production was recycled and still 50% of the residue was disposed of in landfills. Therefore there is still a large scope for improving the situation.

The use of shredded tires as tire derived aggregate (TDA, Humphrey, 2007) in civil engineering works has a number of benefits from the environmental viewpoint. First, it is a low-cost recycle product, because large sizes (up to 30 cm) might be employed and the production costs are lower than for finer materials. Second, it has a large consumption potential: thousands of tons of residue may be employed in a single project. Thirdly, exploiting its properties (mechanical, hydraulic, acoustic, thermal) may offer substantial improvements on construction costs in a number of circumstances.

The mechanical property of TDA fill that has attracted more interest up to now is its being lightweight. TDA fill may substitute advantageously for other construction lightweight materials (expanded clay, polystyrene). A lightweight fill has advantages when building over low-bearing capacity soils or when fill loads over or onto structures.

TDA fill has been already employed successfully in a number of civil engineering projects. The vast majority of these projects have been embankments; there is a more limited experience in other applications, like retaining walls. To consolidate this experience and expand into newer applications, some fundamental knowledge of the TDA mechanical properties seems advantageous.

Figure 1. Granulometric curves of the TDA samples employed in this study.

Laboratory studies of TDA have been already numerous (Humphrey et al., 1993; Ahmed, 1993; Drescher et al., 1999; Lee et al., 1999; Moo-Young et al., 2003). However, there are still a number of open issues with respect to TDA mechanical behaviour. A prominent one is how best to model this material: a comprehensive constitutive model is still lacking. With direct bearing on this main problem a second one appears: how best to test this material on the laboratory? The sizes of most TDA employed as fill are larger than what is easily tested with conventional soils laboratory equipment. If the same material employed in field applications has to be tested large and cumbersome specimens are required. However, if smaller TDA sizes are tested there might be doubts about how representative are the results obtained for field applications.

This last question can be summarized as follows: is there any significative size effect on TDA mechanical response? Some results from an experimental campaign specifically designed to answer that question are presented in this communication.

2 MATERIALS AND METHODS

Several samples of TDA were sent from a commercial shredding operation to the geotechnical laboratories at UPC and CEDEX. The granulometric curves of these samples are presented here in Figure 1. The main identification characteristics of the samples are summarized in Table 1, including median grain diameter, D₅₀, specific weight, G, initial water content, w_ini, maximum adsorbedwater w_max. The smaller sized samples have a more uniform granulom...

Table of contents

• COVER PAGE
• TITLE PAGE
• COPYRIGHT PAGE
• PREFACE
• ORGANIZATION
• ACKNOWLEDGEMENTS
• PHOTOGRAPHS
• ABOUT THE EDITORS
• KEYNOTE PAPERS
• SPECIAL INVITED LECTURES
• THEME LECTURES
• TECHNICAL PAPERS