EXPERIMENTAL STUDY ON THE PHYSICAL AND MECHANICAL PROPERTIES OF GRAVEL-RUBBER MIXTURES AS GSI

Geotechnical Seismic Isolation (GSI) is a potential and emerging technique to mitigate the earthquake effects on structural systems; different geo-materials can be used as GSI, among which Gravel-Rubber Mixtures (GRMs). Rubber grains used for GRMs are obtained from scrap tyres, thus being an effective way to recycle and reuse End-of-Life Tyres (ELTs), whose disposal is an environmental and health issue. The evaluation of the physical and mechanical properties of GRMs is one essential and preliminary step for their adoption as GSI systems. In addition, the availability and cost efficiency of the gravel type and recycled rubber should be carefully considered based on the geographical context. This experimental study investigated the GRMs obtained by typical angular gravels of the central part of Sicily (Italy) mixed with tyre rubber particles. The GRMs were prepared at different volumetric rubber content (VRC) of 0%, 10%, 30%, 50% and 100%. Laboratory compaction tests were performed to understand the compaction properties. In addition, consolidated compression triaxial tests were carried out to evaluate the strength, deformations and strain energy of the GRMs under three levels of confining pressure (50, 100, and 150 kPa). The results indicated that the relative density of the samples and the angular shape of gravel grains influence the strength, deformation and energy-absorbing properties of GRMs. The experimental results were compared with those in the literature on GRMs as GSI; the tested GRMs show a higher angle of shear strength, more dilative behaviour, and higher energy-absorbing capacity.