The contractor said its North Goonyella contract remained suspended due to a fire last year, however, it was expected to restart in the next eight months.
"Margin improvement was hampered by suspension of North Goonyella contract and geotechnical issues at Narrabri and Wambo development projects," the company said in a presentation on its H1 2018 results.
"Contract terms continued to be improved as opportunity presented."
Mastermyne's tendering pipeline is at more than $2 billion, with $1.2 billion in core business, and $800 million in whole-of-mine projects.
New contracts have been awarded at Anglo American's Grosvenor mine for secondary support and its Aquila mine for initial mine establishment works.
Contract extensions have also been secured at Wambo, Integra and Appin projects in New South Wales.
Fleet rates continued to improve in H12019 and utilisation was maintained above 86%.