Concatenate with times of day

I have a formula where you can put in a time ("9:00 AM") and then the following cells will format for every half hour, i.e.:

9:00 AM

9:30 AM

10:00 AM

10:30 AM

11:00 AM

11:30 AM

12:00 PM

I wanted to change it so that it now read, "9:00 AM to 9:30 AM." When I tried this with concatenate, it converted them to numbers, i.e., 0.375 to 0.395833333333333.

OK, well then, I tried converting the original cells to text. So now I have two columns of cells reading (as text, not formula):

9:00 AM -- 9:30 AM

9:30 AM -- 10:00 AM

10:00 AM -- 10:30 AM

10:30 AM -- 11:00 AM

11:00 AM -- 11:30 AM

11:30 AM -- 12:00 PM

12:00 PM -- 12:30 PM

However, when I concat the plain text cells, it still reads as numbers.

Can anyone tell me how to create a formula for this?