Improving sustainability on tunnelling projects through efficiency

The challenge

Steel fibre reinforced concrete (SFRC) has been used in numerous segmentally-lined tunnels in Australia over the last decade.

Precast segment manufacturers work toward a common goal: to strip moulds as soon as possible to increase production speed and capacity. To achieve this, manufacturers require high early strengths from the concrete. However, these high early strengths lead to concrete strengths of 70-90Mpa or even more, which can cause steel fibres used for reinforcement to snap.

The solution

GLC chose high performance steel fibre Dramix® 4D 80/60BGP. Similar to other Dramix® products, these fibres offer tensile strengths of 2,200MPa compared to 1,850MPa, to better handle high strengths.

For the Sydney Metro West – Western Tunnelling Package, Dramix® 4D 80/60BGP coupled with highperformance concrete allowed the project team to reduce the dosage rate to 28kg/m3 while still achieving the required residual flexural strengths.

Bekaert previous segmental projects used 35-40kg/m3 rates, this creates significant financial savings as well as improvements to the project's sustainability.