What is the minimum slope for an exterior concrete slab to properly drain water, but not to be so much a slip hazard?

This question contains two parts going in different directions.

The typical answer (the one supplied by most building codes) is 1/4″ per foot for drainage. The actual minimum slope for drainage is closer to 1/64″ per foot. At that slope gravity stops becoming the driving force behind water. Air movement, surface tension, and capillary flows start dominating water movement.

At what point does concrete become a slip hazard? This varies a great deal. Again, if we go by values supplied by code it gets placed at 6% slope (6′ per 100′). Actually, a lot of codes use roughly this slope to warn about a number of conditions.

Basically, water drainage we predict, slipperiness is dependent on specific conditions of you walking on the concrete.