SILICA (SILICON DIOXIDE-SiO2) is an ever-increasing raw material used in rubber compounds. In recent years silica usage has increased in the rubber industry, especially in the tire industry. As a non-black filler, silica provides improvements in adhesion, abrasion resistance, age resistance, and tear strength. Because of these property improvements, silica is used as a reinforcing filler replacing carbon black, but more often used in conjunction with carbon black. In many applications, silica is used with an organosilane coupling agent. Because they are so closely linked, the two are discussed together in this section.