BOSTON -- Bartolo Colon threw a side session yesterday afternoon, his second in the last three days, and is set to rejoin the Pawtucket Red Sox for a rehabilitation stint.

The veteran right-hander, who has been on the disabled list since June 17 because of a lower back strain, will travel with the PawSox to Scranton. He’s scheduled to make a start Tuesday night and will be expected to work two innings to build up his arm strength.

Colon, who signed as a free agent last spring, won his first three starts and was 4-2 with a 4.09 earned-run average in six outings for Boston after his contract was purchased from Pawtucket on May 21.

David Aardsma, who was placed on the DL on July 20 because of a right groin strain, is expected to work an inning for the PawSox at McCoy tomorrow.

The Sox will proceed slowly with Aardsma, making sure he doesn’t suffer any setbacks as he works his way back to Boston. It’s probably the right-hander, who is 3-2 with a 2.75 ERA in 38 games out of the bullpen, will be rejoining the Red Sox sooner than later.

skrasner@projo.com