During construction of road and railway projects, expansive soils may be encountered. Their use as construction material for embankments presents difficulties, due to their tendency to swell or shrink. Traditional solutions include mixing soil with cement or quicklime, or to import materials from other locations. As an alternative to these solutions, the present paper proposes a less expensive and more sustainable solution, consisting in mixing the natural expansive soil with rubber particles obtained from scrap tyres. Especially, the "Facies Tap" (a typical soil of southeastern Spain) is studied in this paper. This soil, which is mainly a white argillaceous marlstone, is mixed with six different amounts of rubber content (2.5, 5, 10, 15, 20 and 25% in terms of weight) and submitted to several geotechnical tests, including compaction, free swelling, unidimensional consolidation, direct shear testing and undrained shear compression. The addition of rubber particles to the soil up to a 15% makes it lighter and less prone to swelling, while compressibility remains similar to the natural soil and the drained shear strength slightly increases. Based on experimental results, the optimum rubber content mixed with the soil to prevent its swelling is established at around 3%.

No abstract

No abstract

No abstract

Insa Franco, R.; Hidalgo Signes, C.; Martínez Fernández, P.; Medel Perallon, E. (2015). Characterisation of an unbound granular mixture with waste tyre rubber for subballast layers. Materials and Structures. 48(12):3847-3861. doi:10.1617/s11527-014-0443-z. Abstract. Scrap tyres are a solid waste material produced in large quantities. One potential way of disposal is to use rubber particles from shredded tyres as a construction material. Within this context, this paper presents a comprehensive set of laboratory and field tests carried out to evaluate the characteristics of coarse aggregates mixed with rubber particle. The main objective is to assess whether these mixes could be used to form the subballast layer in new railway lines. All the technical features usually required for subballast were tested, including degradation, bearing capacity, density, resilient modulus, etc. The results show that adding between 1 and 10% of rubber (in weight) improves resistance to degradation. On the other hand, bearing capacity is reduced, but still well over the usual range for common subballast if the rubber content is limited to less than 5%. Moreover, the extension and compaction of these mixes can be done using conventional construction equipment. 1 CHARACTERISATION OF AN UNBOUND GRANULAR MIXTURE WITH WASTE TYRE RUBBER FOR SUBBALLAST LAYERS