About 50 janitors who work at Providence College began a three-day strike yesterday after negotiations failed to bring about an agreement on a new contract.

The workers are members of the Service Employees International Union Local 615, which represents some 12,000 janitors across New England. Their contract with Hurley of America, the subcontractor that Providence College hired for cleaning services, ended at midnight Thursday.

The strike began yesterday about 7 a.m., when the workers formed picket lines around two of the main entrances to the campus, one on Huxley Street and another on Eaton Street. The union said it planned to end the strike tomorrow, with the janitors returning to work Monday.

The strike comes just as Providence College is playing host to a large number of visitors. This is Family Weekend for upperclass students, and about 700 families are expected to attend, said Ed Caron, vice president of the college. That would probably bring about 1,000 visitors to the Providence campus, which has about 3,800 undergraduate students.

Caron said the dispute was between Hurley and the union, and that the college cannot intervene as a matter of law.

“Under federal law, we cannot be involved in the negotiations,” he said. Some students have requested that the university intervene, but Caron said that “it’s not a choice.”

He said that pickets were orderly and civil yesterday, and that the campus was operating normally. There were some workers from Hurley who cleaned the 49 buildings on campus as usual.

Sasha Warner-Berry, an organizer for the union, said the main issues behind the strike were pension and wage increases, as well as the term of a new contract.

Right now, the janitors make between $11.43 and $11.89 an hour, depending on the shift.

“The company’s offer did not come close to where we wanted to see the wage increase,” she said. “Our goal is not only to have a cost-of-living increase, but also to help move the families out of poverty.”

The janitors, Warner-Berry said, make only about half of what the Rhode Island Poverty Institute says a Rhode Island family needs to cover their basic necessities.

As for pensions, she said the company had proposed a five-year contract with no increase in pension benefits, but the union wanted some increase over that period.

A spokesman for Hurley of America in Boston did not return a call for comment.

However, Hurley has posted a “fact sheet” on campus to tell its side of the dispute. It said the union “walked away from a generous offer and ordered its members to strike.”

The company said it offered the union a wage increase of 50 cents per hour per year over five years. That amounts to increases of 3.7 to 4.4 percent each year, or a total of about 22 percent over five years.

The company said it would continue to provide 100-percent employer-paid health insurance, a pension plan and an optional 401(k) plan, additional paid time off and increased paid vacation. The offer represented a total compensation increase of nearly 30 percent over the five years, Hurley said.

On the picket line yesterday, the janitors were joined by students and professors, many of whom have shown support for the union’s cause, said Warner-Berry. Besides marching with the pickets, students brought them coffee, food, scarves and gloves on a day that was rainy and cold.

She said that some 20 or 25 teachers either canceled classes, or moved them off campus, in support of the striking janitors.

tbarmann@projo.com