Caggiano, Antonio, Institute of Construction and Building Materials, Technische Universität Darmstadt, Franziska-Braun-Str 3, 64287 Darmstadt, Germany, caggiano@wib.tu-darmstadt.de www.wib.tu-darmstadt.de CONICET, INTECIN, Facultad de Ingeniería, Universidad de Buenos, Italia