It is what the Church calls a valid, natural marriage. It is not a sacrament:
Can.* 842 §1. A person who has not received baptism cannot be admitted validly to the other sacraments.
Marriage between the baptized is, by its nature, a sacrament:
Can.* 1055 §1. The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life and which is ordered by its nature to the good of the spouses and the procreation and education of offspring, has been raised by Christ the Lord to the dignity of a sacrament between the baptized.
§2. For this reason, a valid matrimonial contract cannot exist between the baptized without it being by that fact a sacrament.