Laboratory Characterization of a Reclaimed Rubber Compound for Low-Cost Elastomeric Isolators

Abstract

Although seismic isolation devices are effective in protecting structures during an earthquake, they are generally large, heavy, and expensive, making their application prohibitive for housing buildings. In the last few years, different strategies have been investigated to make seismic isolators cheaper and lighter for housing buildings in developing countries. Lower costs can be obtained at different scales: simplifying the installation process of devices, reducing energy consumption during manufacturing, and using recycled materials. Both weight and cost of isolators could be reduced by adopting flexible reinforcements in place of steel reinforcing plates, also allowing easier installation without bolted connections in unbounded configuration. Costs can be further reduced by replacing natural rubber with a recycled elastomer. It has been demonstrated that trying to give a second life to rubber is challenging, since devulcanization process, capable of breaking chemical bonds between rubber and sulphur, is highly polluting and requires high consumption of energy. In the present work, a recycled compound has been preliminary developed with mechanical properties not significantly lower than virgin rubber. Obtained parameters are satisfactory for use in unbounded isolators with flexible internal reinforcement where internal stresses are significantly reduced. In particular, a novel compound has been properly formulated in order to be lower cost in comparison to traditional one. Mechanical characterization of the material showed excellent properties including shear modulus and hardness similar to those of a soft rubber, even if a reduced ultimate deformation capacity is achieved. Furthermore, rubber adhesion with different fabrics has been investigated. Preliminary results are very promising and pave the way for the development of high-performance and low-cost rubber isolators.