Is this an AC or DC signal?
DC + AC = DC

Plainly put: No.
It's AC with a DC offset, if you will.
This is less about whether the sign changes (that sign is just relative to some arbitrarily defined reference), but about whether the energy transport happens mainly in the DC or AC component.
That's all that makes the difference between &quot;AC with DC offset&quot; and &quot;DC with AC ripple&quot;.