Concrete is a highly alkaline material which reacts chemically with oil or alkyd based finishes to weaken their adhesive bond. This will gradually generate a sandy or dust-like condition at the surface. Grade level or sub-surface floors are continually subjected to moisture penetration. All concrete should be cast over a vapor barrier. Sub-surface concrete should also be case over a generous level of gravel with further means to remove water when conditions are severe.
Moisture is the primary cause for adhesion failure.
Other possible causes include hard-troweled concrete which presents a physical barrier to adhesion by not permitting penetration of coatings. Older concrete can become crumbly, and accumulations of grease or oil create a barrier limiting adhesion. Remove paint by scraping and sanding. Clean floor by scrubbing with hot water and a strong detergent solution. Avoid mild dishwashing detergents.