Premix based on selected hydraulic binders, perfectly spherical closed-cell expanded polystyrene beads with a maximum diameter of 2 mm with high thermal insulation power, treated with specific additives that ensure a homogeneous mixture, avoiding EPS flotation phenomena. Suitable as a lightweight screed for embedding pipes and systems and for single-layer screeds suitable for direct laying of ceramic floors with cementitious adhesive (see specifications below). Certified recycled content of 15%.