Adhesives and Sealants Both precipitated silica and calcium carbonate are used in adhesives and sealants. Silica is used to improve physical and rheological properties in automotive and construction sealant systems including PVC, plastisols, polysulfides, urethanes and epoxies. Calcium carbonate is used as a cost reducing extender in adhesive products. These innovative chemicals provide for Rheology control Tear resistance Abrasion resistance Air permeability Extension Flame retardance Smoke supression Reinforcement Thickening