Overview

The $1.86 billion Forrestfield-Airport Link project jointly funded by the Australian and WA governments comprises twin bored tunnels adding 8.5km to the rail network with three new stations—Redcliffe, Airport Central and High Wycombe, two of them underground. In April 2016 the PTA awarded the design, construct and maintenance contract to Salini Impregilo – NRW Joint Venture.

The design of the tunnel track slab evolved from a conventionally reinforced concrete design to a macro synthetic fiber reinforced concrete track slab, enabling significant construction efficiencies and program savings. Further efficiencies were observed in the method of placement, which eliminated a significant amount of in-tunnel truck movements by pumping the track slab concrete from the top of each station box along the tunnel alignment. This meant that in some sections of the tunnel, concrete was being pumped almost two kilometers.

The talk will start with a discussion on trackslabs in general as well as some background on concrete pumping considerations to lay the foundation for an in-depth look at the construction of the Forrestfield-Airport Link trackslab concentrating on aspects such as the pumping the concrete mix design, and the field trials leading up to the final record-breaking pump of almost 2000 meters.

Speaker

Des Vlietstra

Des has a MSc Eng in Advanced Concrete Technology and a Graduate Diploma in Mining Engineering. He started his career in underground mining and rock mechanics which somehow evolved into concrete. He has a special interest in concrete pumping and sprayed concrete which is essentially pumped concrete applied pneumatically. He is an EFNARC nozzleman examiner for robotically applied sprayed concrete and a certified ACI-ICT EN Standards Concrete Field-Testing Technician. Des is a member of the Institute of Concrete Technology and sits on the executive committee of the Australian Shotcrete Society as well as the WA committees of the Concrete Institute of Australia and the Australian Tunnelling Society. Apart from being passionate about concrete and underground space he also enjoys photography.