Astacio is a hard-throwing righty at six-foot-five and 200 pounds. The team liked his potential and added him to the 40-man roster prior to the season.
Astacio has spent the last two years in the Pirates' Minor League system, including a stint in Double-A Altoona last season. The 23-year old hails from the Dominican Republic.
The Pirates have also announced that injured shortstop Jack Wilson has begun rehab with the organization's extended Spring Training team.
Wilson has been sidelined with a left calf strain since April 3, and the Bucs have struggled to find a suitable defensive replacement.
Wilson will play on Thursday and Friday, then likely head to Altoona to play there on Saturday.
Michael Phillips is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.