Air entrainment was found out accidentally within the mid-1930s.[2] At that time, cement manufacturers were being using a grinding help to reinforce the whole process of grinding cement. This grinding aid was a mixture of various chemicals, like salts of wood resin, which were being included towards the cement in https://ebs-emulsion-cas-no-110-361481.fireblogz.com/66654704/the-smart-trick-of-concrete-accelerator-curing-time-that-nobody-is-discussing