Are there scholarships that are purely based on academics, without the addition of essays?

Not very many.
The only scholarships that will be purely academic-based will be some of the entrance scholarships you are applying for through the universities (and even many of those will factor in your extra-curricular activities). 

Almost all scholarships want to get a sense of who you are as a person and your commitment to the school/community so that is why they ask for an essay.