BarChip Fibre Reinforced Shotcrete
El Melón II Road Tunnel, Chile
BarChip fibre reinforced shotcrete is supporting the 2.8 km El Melón II tunnel in Valparaíso, Chile. Located approximately 150 km north of Santiago on Chile’s 2000-mile Route 5 highway, El Melón II is built parallel to the existing Melón I tunnel. The total project consists of around 5 km of new roadworks of which 2.8 km will be El Melón II Tunnel. The original tunnel will run in the southbound direction while El Melón II tunnel will run northbound, enabling continuous 2 lane traffic in both directions with a maximum speed of 120 km/hr.
El Melón II is a 2-lane tunnel approximately 8 m high and 11 m wide. The initial ground support consists of BarChip fibre reinforced shotcrete with rock bolts. The shotcrete was specified for 30 MPa at 28 days with a maximum aggregate size of 10 mm and a slump of 220 mm. The specification called for an early age performance of 500 Joules at 7 days and 700 Joules at 28 days, tested according to EFNARC.
During mix design and optimisation 5 different fibre options were tested. The BarChip fibre solution, developed through close cooperation between BarChip, the project consortium and the shotcrete supplier, offered the highest performance and the best workability and was subsequently chosen for the project’s shotcrete mix.
Tunnel excavation works were completed in late 2020 with no major issues recorded. The Barchip shotcrete solution, batched and delivered by Melón Hormigones S.A, surpassed all quality controls and performed in-line with results seen during controlled testing.