Magnasite flooring

I need to fill in some hollows/low spots in my magnesite floor, (magnesite laid over a concrete slab). I know I can use self levelling cement but at $40 per bag that it will be very expensive given the area so I was thinking of using a pre mixed sand cement mix instead and screeing it over the magnesite. I need to be able to feather the cement/sand mix from a depth of 18mm at the lowest spot in the magnesite floor to 0mm at the highest spot. I am wondering if it is possible to use a cement sand mix for such a shallow job? I need to do this because I want to lay a floating timber or laminate floor and at the moment the floor is not flat enough. I have painted the magnesite with Bondcrete to seal it and to help the cement stick to it. I have been told that if I also mix Bondcrete into the cement/sand mix this will allow me to use such a thin spread of cement without it crumbling, especially near the edges where it feathers to nothing. Should I use extra cement into the mix to make it stronger? Please help. Thanks in advance.


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