STRENGTH CHARACTERISTICS OF TYRE CHIPS-SAND MIXTURES

Abstract: Waste tyres are more and more widely used for geotechnical applications as backfill material that is either a substitute for natural soils or combined with them. Beyond the economical and environ-mental concern, these materials can help solving problems with low shear strength soils. This study aims at investigating a mechanical behaviour of tyre chip–sand mixtures thanks to a triaxial tests campaign. Two factors were studied: (i) the tyre chip content, from 0 to 100% by mass and (ii) the orientation of the pieces of tyre, with four varying orientation conditions. This paper focuses on the stress–strain behaviour of the different mixtures and their volumetric variation during the tests. The angle of friction and cohesion for each mixture are presented. The optimum percentage mass and optimum unit weight, which gives the maximum shear strength, are also determined. The influence of the different parameters is discussed. 1. INTRODUCTION Tyre disposal is a huge challenge faced by waste management engineers, particu-larly in more economically developed countries where there exist stockpiles of tyres in alarming volumes. Their disposal proves to be a serious problem as tyres do not de-compose. Waste tyres pose a threat to public health and to the environment in terms of current methods of their disposal due to the following three reasons: (i) they occupy large volumes in already overcrowded landfills, (ii) waste tyre storage can be a dangerous fire risk, (iii) waste tyre dumps provide the breeding ground for vermin, including rats and mosquitoes.