Two former managers of a company convicted of supplying substandard concrete to the Big Dig highway project in Boston have avoided prison time for their roles in the scheme.

A federal judge on Wednesday sentenced 64-year-old Robert Prosperi of Lynnfield and 53-year-old Gregory Stevenson of Furlong, Pa., to three years of probation, including six months of home confinement.

Federal prosecutors had requested prison sentences of at least seven years for each former manager at Aggregate Industries Inc.

U.S. Attorney Carmen Ortiz said the government was "disappointed" with the sentences because they do not "reflect the seriousness of the offense."

The men were convicted in August of 135 felonies, including conspiracy to commit highway project fraud. Their lawyers argued for leniency because they did not profit personally from the scheme.