Multifunctional thin layers with Gipave® in Sardinia

In summer 2021 Iterchimica, thanks to the collaboration with the University of Cagliari, ANAS, Impresa Aurelio Porcu & Figli and the contracting company De Sanctis Costruzioni SpA, created a technical solution aimed at solving some problems that affected a section of pavement road in Sardinia. The solution involved the creation of a thin layer of 1 cm of bituminous conglomerate (micro-paving) containing Gipave® which made it possible to avoid the demolition and reconstruction of the binder layer and the consequent consumption of raw materials.

The work involved a stretch of over 5 km on the current SS 125 of Cagliari, in particular the 1st Lot of the Tertenia – San Priamo section, part of the road connection from Cagliari to Tortolì. The initial project involved the creation of a 15 cm foundation layer, a 15 cm sub-base layer in cemented mix, an 8 cm base layer in bitumen mix, a connecting layer (binder) in bituminous conglomerate with modified bitumen of 7 cm and one of draining wear of 5 cm.

The solution developed by Iterchimica and the Research Team was adopted following the problems encountered during the post-production tests conducted by the official laboratory in charge: as regards the binder layer, a slight lack of sand was highlighted compared to as foreseen by the mix design. The analysis of the results, in fact, highlighted that if on the one hand the excessive porosity of the bituminous mixture would not have affected the mechanical performance of the binder, on the other it could have limited the durability of the layer in the long term.

Considering floors, drains and levels, it was considered interesting to evaluate the possibility of creating a thin layer of 1 cm of highly performing bituminous conglomerate to better absorb and distribute the load to the lower layers, reducing the deformation not only of the binder layer but of the entire flooring. The thin layer was also designed with the function of completely sealing the binder layer, improving the waterproofness of the drainage installation surface.

The results of the tests conducted demonstrated a general improvement in performance due to the presence of the thin layer and a clear increase in the stiffness of the binder layer.

Micro-paving has allowed us to obtain environmental benefits: it has in fact made it possible to avoid the destruction and reconstruction of 1.749 t/km of modified binder, compared to the installation of only 250 t/km of micro-paving with supermodifier at graphene base (Gipave®).