Searching Limerick Workhouse Records

Hello,

I have hit a roadblock searching for my great-grandfather's family.

The mother of the family died young in 1872, leaving 5 children under the age of 14. I wonder if at least the younger children ended up in some kind of state/county care.

Does anyone have thoughts about searching for orphans or workhouse records, or any thoughts about what may have been the course of events for a family like this in LImierick in 1872? 

My great-grandfather would have been 9 years old when his mother died in 1872, and he came to the U.S. about 1891. Where he could have been in between, is my research question.

Thanks for any thoughts!