A plasticized PVC formulation for foam extrusion including polyvinyl chloride, at least one plasticizer, at least one nucleating agent and a chemical blowing agent, wherein the plasticized PVC formulation is a dry blend containing 0.5 to 5% by weight of one or more nucleating agents and 0.1 to 3% by weight of the chemical blowing agent, wherein the blowing agent is sodium bicarbonate and the nucleating agent is talcum, and a foam extrusion method using said formulation. The extruded plasticized PVC foam is particularly suitable for rock shield pads used for pipeline protection. The foams are lightweight and require less consumption of materials with comparable properties to corresponding solid articles.