1. SINTEF Applied Chemistry, P.O. Box 124, Blindern, 0314 Oslo, Norway, Norwegian Building Research Institute, P.O. Box 123, Blindern, 0314 Oslo, Norway, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway, and Department of Structural Engineering, NTNU, 3034 Trondhein, Norway