Good afternoon, @Georgiana 
- and welcome to our comunity 
The short answer is yes. 
Indeed, you can add all your volunteer work experiences to your LinkedIn account.
You may, however, need to ask for a certificate from organizations you work with as a volunteer to prove that information (or for someone working there to act as a referee for you) if you apply to a job.
Also, you may want to have a look at the Community Recognition Program. I believe you will find it useful.
Happy translating! 
I hope this helps.
Have a great afternoon, Georgiana. 