It’s actually a biochar from spent coffee grounds. Biochar is a process of slow burn in a low oxygen environment.
So 1: it doesn’t resemble coffee by the time it’s put in. Closer to charcoal. Cute jokes about how nice the concrete will smell are fun, but off base.
And 2: Coffee probably isn’t the only base you could use for the biochar. It makes for a cute fuzzy headline that people love to share but it could prove more effective and economical in the end to make a biochar out of lentil chaff or something else. We need to see this put into practice at scale before we have any idea if gathering up coffee grounds from cafes to make concrete makes sense at all.