Most definatly! It contributes to keeping the pH high. However, you can do the same thing with careful measuring of sodium bicarbonate....and then use sand for the nicest look, maintenance and digging possibilities.
I have crushed coral in my 55g, but I wish I had used sand because for one thing, algae has grown on the crushed coral and makes it look dirty, and because it traps alot of debris--just like any gravel would.
If you want to use crushed coral to help buffer the water, but still want the option of using sand in the tank, you do have the option of filling a canister filter up with the CC.