Here are a few quotes from canon law that might help explain the sacramental aspect etc:
“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.”
“Can. 1061 §1. A valid marriage between the baptized is called ratum tantum if it has not been consummated; it is called ratum et consummatum if the spouses have performed between themselves in a human fashion a conjugal act which is suitable in itself for the procreation of offspring, to which marriage is ordered by its nature and by which the spouses become one flesh.
§2. After a marriage has been celebrated, if the spouses have lived together consummation is presumed until the contrary is proven.”
You can read more here:
vatican.va/archive/ENG1104/__P3V.HTM
(you can click next to keep reading the different subtitles under marriage)