Longtime customers of concrete giant Boral chose other suppliers during a two-year union ban on the company, to avoid the dispute.

So says Boral as it seeks more than $28 million in damages following a two-year black ban placed on it by the CFMEU in 2013-2014.

On the first day of a four-week hearing at Victoria’s Supreme Court on Monday, Boral’s lawyer Stuart Wood QC said union heavies used intimidation and conspiracy tactics to stop Boral trucks being allowed onto construction sites.

The court was told Boral was targeted by the union because it had continued to supply concrete to construction company Grocon, with which the union had an ongoing battle.

In his opening statement, Mr Wood said some customers told Boral staff they would rather choose another concrete supplier than endure delays and other action that the union had threatened.

Often alternative suppliers cost more than Boral but it was deemed a small price to pay to avoid getting caught up in the dispute, he said.

Boral wants damages for losses on 16 specific projects, loss in market share from 2013 and in the future and reduced profits because they needed to discount to entice customers to continue to use them.

Mr Wood said many customers had the mindset that: “you do what the union says or you don’t get work”.

This attitude meant Boral lost the opportunity to supply a large number of projects including Werribee Plaza, Olympic Park, Ballarat Aquatic Centre and Swinburne University in Hawthorn.

He said 14 customer witnesses would be called over the next month, many who would be subpoenaed to appear.

By Melissa Meehan