Air Entrainment was discovered accidentally from the mid-1930s.[two] At that time, cement manufacturers were using a grinding help to reinforce the process of grinding cement. This grinding aid was a mixture of varied chemicals, which includes salts of wood resin, which had been additional on the cement during the grinding https://ebs-emulsion-cas-no-110-305825.ka-blogs.com/88643513/rumored-buzz-on-fiber-for-concrete-mix