Hydraulic Lime : A variety of calcined limestone which, when pulverized, absorbs water without swelling or heating and yields a cement that hardens under water
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}