1 Physical Chemistry of Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland.
2 Department of Architecture, MIT, Cambridge, MA, USA.
3 Department of Civil and Environmental Engineering, MIT, Cambridge, MA, USA.
4 Building Archaeology and Construction History, Deptartment of Architecture, ETH Zurich, Zurich, Switzerland.
5 Physical Chemistry of Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland. flattr@ethz.ch.