Breakthrough of the Santa Lucia Tunnel

With its 15.9 m of diameter, the TBM used for the “Santa Lucia” tunnel in Italy has been the largest one ever used in Europa. The company “Pavimental S.p.A.” has driven this machine to excavate the 7.5 km of tunnel along the highway A1, between Bologna and Florence. MAPEI UTT has successfully participated in the realization of this impressive tunnelling project, providing most of the chemical products used for the TBM excavation. For the soil conditioning, Polyfoamer ECO/100 has been chosen after a selection among 8 products, being the foaming agent with the best combination between high technical performances and low environmental impact. Thanks to its quick biodegradation and minimum eco-toxicity, its use has avoided the classification of the muck as a “waste” and has minimised the time necessary to temporary stock the muck in the job-site area before its final disposal: an average of 7 days with the Polyfoamer ECO/100 against 28 days necessary with the other foaming agents. Also, the Mapequick CBS System 1L (retarding agent with plasticising effect) and Mapequick CBS System 3 (accelerator) have been used for the injection of the two-component backfill grout behind the tunnel lining. Finally, the 32.000 segments, with a thickness of 60 cm, have been produced by the company “Maccaferri S.p.A.” using our Dynamon NRG1015S, superplasticiser admixture specifically designed for the precast concrete industry.