Energetically Modified cement (EMC) containing up to 70 % of pozzolans have been tested to have the ability to deliver long term pozzolanic reactions (calcium oxide + wateer + silicon dioxide) leading to the formation of additional amounts of C-H-S gel. This can fill voids and cracks of widths up to 0,2 mm, up to twice the crack width that usually can be healed. EMC is Portland cement mechanically activated in a process with a pozzolan, silica sand or blast furnace slag. The process was discovered 1992 at Luleå University of Technology and has been further developed since then.