No there is expression in Mendix which could add bussiness days. So you have to build your own logic to skip weekend days. You could create easily a microflow which automatically skips weekend days.
You can do that by checking your date with formatDateTime($object/Date1,"EEE")
. If it's 'Sun' or 'Sat' you need to add another day till it isn't a weekend day.
Hi Marc, please have a look at the non working day calculator in the Mendix AppStore. That will probably help you.