Convert Excel NumberFormat to string

Greetings,

I would like to concatenate a string value to a numberformat as fraction, the issue is when I contatinate a string value it reverts back to a decimal.
/
Cells(r, i + 1).NumberFormat = "# ?/?"
Cells(r, i + 1) = Str(Cells(r, i + 1))
/*
Produces----> 5/8

while this
/
Cells(r, i + 1).NumberFormat = "# ?/?"
Cells(r, i + 1) = Str(Cells(r, i + 1))
Cells(r, i + 1) = Cells(r, i + 1).Value & " Day"
/*
Produces----> 0.625 Day

Any assistance would be greatly appreciated, thanks in advance for any help and support.
Best Regards