The results are presented of an experimental study, aimed to evaluate the suitability of different types of marginal materials, recycled in the lithic skeleton of bituminous mixtures for flexible road pavements. The investigation involved a preliminary study of the physical and geotechnical properties of the granular materials, namely RAP aggregate, steel slag, foundry sand, bottom ash from municipal solid waste incineration (MSWI); then a mechanical characterization of the bituminous concretes was done. The mixtures were mechanically analyzed by means of conventional and advanced testing procedures, such as Indirect Tensile Strength (ITS) test, Indirect Tensile Stiffness Modulus (ITSM) test, and four Point Bending test (4PBT), in order to investigate strength at failure, stiffness, fatigue life and moisture resistance. The results have been really interesting and evidenced useful applications: the binder bituminous mixtures presented an Indirect Tensile Strength up to 2.35 MPa and the Stiffness Modulus, at 25°C and 25 ms, up to 11,904 MPa, depending on the marginal aggregate contents; the same parameters, resulted to be up to 0.85 MPa and 8,567 MPa, respectively, for foamed bitumen bound mixtures. Given the positive mechanical performances, it has been verified that by-products can be used as substitution of the natural lithic materials in the road layers, also with relevant contents on the weight of the aggregate, up to 97%, depending on the specific application.
Re-use of marginal materials in bituminous mixtures for road pavements
BALDO, Nicola
2012-01-01
Abstract
The results are presented of an experimental study, aimed to evaluate the suitability of different types of marginal materials, recycled in the lithic skeleton of bituminous mixtures for flexible road pavements. The investigation involved a preliminary study of the physical and geotechnical properties of the granular materials, namely RAP aggregate, steel slag, foundry sand, bottom ash from municipal solid waste incineration (MSWI); then a mechanical characterization of the bituminous concretes was done. The mixtures were mechanically analyzed by means of conventional and advanced testing procedures, such as Indirect Tensile Strength (ITS) test, Indirect Tensile Stiffness Modulus (ITSM) test, and four Point Bending test (4PBT), in order to investigate strength at failure, stiffness, fatigue life and moisture resistance. The results have been really interesting and evidenced useful applications: the binder bituminous mixtures presented an Indirect Tensile Strength up to 2.35 MPa and the Stiffness Modulus, at 25°C and 25 ms, up to 11,904 MPa, depending on the marginal aggregate contents; the same parameters, resulted to be up to 0.85 MPa and 8,567 MPa, respectively, for foamed bitumen bound mixtures. Given the positive mechanical performances, it has been verified that by-products can be used as substitution of the natural lithic materials in the road layers, also with relevant contents on the weight of the aggregate, up to 97%, depending on the specific application.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
