The Blue Book is usually a collection of specifications and details that local governments (Towns, counties, etc.) use as a default for their design and maintenance projects. Larger entities (for example, Clark County, Nevada) have their own set of Standard Specifications. And sometimes these are referred to as Blue Books locally.
I would guess that they mean to use the Blue Book materials as your design assumptions (Class AA concrete is 4000 psi, reinforcing is 60,000 psi, etc.). In my experience, the Blue Book does not have any design procedures or guidelines beyond that.