More than 500,000 tonnes of sandstone will be transported from Metro tunnelling sites at Chatswood and Marrickville to the Western Sydney International site.
More than 148,000 tonnes of sandstone has already been transported to the Airport site since May.
The sandstone is coming from tunnel boring machines excavating the new twin railway tunnels between Chatswood and Marrickville, which are already 50 per cent complete.
Sydney Metro aims to reuse 100 per cent of crushed rock during excavation of the 15.5-kilometre twin tunnels between Chatswood and Marrickville.
Western Sydney International is on track to open for its first passengers in 2026.