ARDEX K 301 Exterior Self-Smoothing Levelling and Resurfacing Compound is a special fast setting cement-based product designed to smooth and level rough and damaged concrete surfaces in external and internal situations. ARDEX K 301 is a grey powder consisting of special ce- ments, graded aggregates and high quality synthetic resins. When mixed with water, a fluid mortar is produced which sets within 2 hours and can normally be walked on after approximately 2-3 hours at 20°C. ARDEX K 301 can be applied from 2mm to 20mm in thickness. The set and hardened ARDEX K 301 is usually ready to receive light wheeled traffic after 48 hours at 20°C.