The conciliator in the dispute asked both sides to take a break earlier Sunday evening to consider some of the issues being discussed, but negotiations later resumed.
About 175,000 construction workers put down their tools last Monday, shutting down work sites across the province.
The main sticking points in the negotiations include wages and working conditions.
Quebec Premier Pauline Marois has said her government won't tolerate a lengthy strike.
If a deal isn't reached soon, Marois could introduce back-to-work legislation before leaving Wednesday for a work mission in Mexico.
Eric Cote, a spokesman for the Quebec construction association, an industry group, said it remains committed to reaching a deal.
"I think after 25 hours of negotiations, it's normal that we can take a step back," he said.