2002 Volume 13 Issue 2 Pages 129-138
Eco-cement is made from municipal waste incinerator ash, which contains much amount of Al2O3 and Cl-. Consequently Eco-cement contains much more amount of interstitial phase and Cl- than OPC. Although 20 to 40 mass% of Cl- in Eco-cement dissolved into free water within 3 hours, Cl- concentration decreased rapidly after that. In the case that Cl- content in cement was adjusted to 0.1 mass% by NaCl, almost all of Cl- in free water was bound as Friedel's salt in mortar with Eco-cement, OPC and Blastfurnace Slag Cement. The value of [Cl-/OH-] molar ratio of free water in each mortar was under 0.6 at 28 days, so steel corrosion is likely not to occur. In the case that Cl- content was increased to 1.0 mass%, Eco-cement bound more amounts of Cl- than other cements by producing much amount of Friedel's salt. Remained Cl- in free water, which was not bound as Friedel's salt was sorbed in hydrates such as C-S-H.
