It also acts a barrier over the concrete and rebar. Depending on the highway, Ontario is now using a rubber-based permeable asphalt top layer that lets water wick away to the lower layer.I imagine it is easier to resurface asphalt on a bridge than the concrete if it begins to wear significantly. Bridges have much longer service life than the road surface.
I hadn't noticed that Quebec has concrete bridge decks. Concrete doesn't play well with salt and can get polished to the point that you can barely stand on it. some stretches of US Interstates are completely concrete. Some of most annoying m/c rides have been on those, with the mind and body numbing expansion joints. I could be wrong but the last stretch of concrete highway in Ontario is/was Hwy 49 between Picton and the mainland.