Perhaps the earliest recognized event of cement is from twelve million yrs back. A deposit of cement was formed after an incidence of oil shale Found adjacent into a bed of limestone burned by organic causes. These ancient deposits had been investigated within the 1960s and seventies.[nine] GRC: glass fibre https://keeganfqqmv.idblogmaker.com/29438262/a-simple-key-for-manufacturing-of-portland-cement-unveiled