Yves Ouellet, spokesman for the alliance of construction unions, said the 175,000 workers had already made several concessions to "reduce the cost of projects" at the request of their bosses and are ready for a lengthy strike.
"The motivation is still there," Ouellet said of picketing workers who marched outside Quebec job sites. "These are issues close to their hearts. It's not necessarily about monetary gains."
He said workers now expect a reasonable offer.
Current stumbling blocks revolve around wage increases and working conditions.
Government conciliator met with both sides on Tuesday but there was no resumption of negotiations.
Jean Pouliot, a spokesman for the construction companies' alliance, described the strike as "an exaggerated tactic" that was premature.
He said the unions had spent months establishing protocols for bargaining, which delayed the start of negotiations.
Pouliot said he believes the conciliator had gotten a clear mandate from the government to get the talks moving.
"That's really what we want — to sit down at the table and negotiate with our employees," he said.
Premier Pauline Marois reiterated Tuesday she has no intention of legislating an end to the strike.
Liberal Leader Philippe Couillard said Marois should consider the option if there is no agreement reached by midnight Friday.