Calcium Carbonate 824 Calcium carbonate 1317-65-3 Whittaker Extenders / Fillers >> Limestone Rubber - Elastomer (Chloroprene, Butyl …) SEALANT >> Putty Calcium Carbonate - Technical Grade (Dolomitic Limestone) Dolomitic limestones are used as fillers and extenders in both solvent and aqueous coating systems. They are also used as fillers and extenders in building products, caulks, sealants, cements, putties, rubber, plastic and many other areas as a lower cost alternative to traditional ground limestone products. Low-cost fillers, increased opacity. Dolomitic limestone. Used as a filler and as an extender in caulks, sealants and putties. Offers increased opacity.