Two options: truncate the dateval field to give you only the date portion or use a calendar table! You will have to do your own performance testing to determine which method is most efficient for you. But remember, just because the code is shorter, doesn't necessarily mean it is better
See this thread for code to create both a numbers and calendar table.
Then you can join your table to this calendar table to give you a way of grouping by day, something like this
ON your_table.dateval >= calendar.the_date
AND your_table.dateval < DateAdd(dd, 1, calendar.the_date)