If cell isnt filled, show nothing. But cell is always filled because there is a function in it?

For example I got those formules in my excel: I got those formules below on the cells B1, B2, B3

[=IF(A1>0;A1;"")]
[=IF(A2>0;A2;"")]
[=IF(A3>0;A3;"")]

So if A1 is filled it shows the number of that cell. If A3 isnt filled it shows nothing ("").

Now in my next row (C1, C2, C3) I want to check if they are empty, if they are empty fill the cell with "" nothing. If they arent empty i want to CONCATENATE them. Example:

=IF(b1>0;(CONCATENATE(b1;"test"));"")
=IF(b2>0;(CONCATENATE(b2;"test"));"")
=IF(b3>0;(CONCATENATE(b3;"test"));"")

But this doenst work... I tried:

IF(isblank(b1);"";(CONCATENATE(b3;"test")))

This also didnt work...

It probably doenst work because in the cells B1, B2, B3 there are formules, so they actually arents empty... But it doenst display anything, so they actually are empty..

Sorry for my bad english I hope someone understand the problem