Cement Mixer Mobile Crusher

Best crusher dust cement mix lecappuccino0100612 hi, would like to know if there any problems using crusher dust for my concrete instead of sand and gravel, the crusher dust has a fair bit of powder so it mixes ok but im want to use it for footings for raised floor of ganny flat, was going to use mix of 41 have used it for chooks pens etc and seems alright but dont know how strong.