The admixture is encapsulated in a material, such as gelatin or wax, which ruptures, shatters, or disintegrates in the wet cementitious mixture during a period of mechanical...http://www.google.com/patents/US5320851?utm_source=gb-gplus-sharePatent US5320851 - Mixture is encapsulated in material which ruptures, shatters or disintegrates during mechanical mixingAdvanced Patent SearchPublication numb