Convert text to date when text has blanks

I have a date field that is defined as text.  I need to convert it to a date field by creating a new calculated field, but some of the records have blanks in this date field, so the simple conversion doesn't work.  I want my calculated date field to filter out these records that have the blank values, but I can't get my DAX formula to work.  I am trying to use a CALCULATE function but the text field with the date values doesn't appear in my formula as I try to build the formula.  I basically want to say New Date Field=calculate(text_date_field, text_date_field <> " ").  I cannot just exclude the records with the blank values from the dashboard because they are needed elsewhere, so I am trying to build a formula