Extraordinary maintenance intervention on the A31 Brescia-Padua

The increase in performance and the improvement of environmental sustainability standards are two of the objectives achieved with the extraordinary maintenance intervention carried out on the A31 motorway in the stretch between Vicenza north and Longare which involved the reconstruction of the entire infrastructure package road. The A31 motorway belongs to the motorway network under concession to the company “Autostrada Brescia Verona Vicenza Padova SpA”. The intervention concerned the emergency, driving and overtaking lanes.

Before starting the works, feasibility and optimization studies were carried out in order to identify the best formulations of the mixtures, with the aim of defining the components of the mixture, the related physical-mechanical characteristics and the dosages necessary for the production of a bituminous conglomerate capable of satisfying the acceptance requirements set out in the Special Tender Specifications.

The most appropriate technical solution was identified in the use of Gipave®, the supermodifier based on graphene and recycled hard plastics. The product, in addition to graphene, is composed of polymers deriving from the processing of recycled plastics otherwise destined for the incinerator and, thanks to its specific formulation, is able to significantly increase the performance of a road superstructure compared to traditional methods.

At the same time, material from the cold demolition of old pavements (milled) was used to package the bituminous mixtures. The maximum percentage of milled material for the base and binder layers was equal to 30% of the weight of the aggregate mixture.

The mixtures used for the maintenance intervention were subjected to performance tests during the mix design and post-production phases.

Four different laboratories were involved in this intervention: one for the mixture design phase and three for the post-production verification phase. The tests carried out were Marshall stability, indirect tensile strength (ITS), measurement of voids using a rotary press, stiffness modulus at different temperatures and resistance to rutting.

The results of all the tests listed above respected the performance requirements included in the Technical Standards of Specifications.

In conclusion, the extraordinary maintenance intervention carried out on the A31 motorway has allowed the creation of a high-performance, eco-sustainable and safe section of motorway for users. In fact, thanks to the use of these additives, we contribute to the reduction of polluting emissions into the atmosphere; this reduction is allowed by two factors: on the one hand the lack of incineration and elimination of plastics, on the other, the extension of the useful life of the road which reduces the need for maintenance and the corresponding production, transport and paving operations which are instead delayed in time.

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