1. Dept. of Engineering and Geotechnical, Univ. of Pescara, Viale Pindaro 42, 65127 Pescara, Italy.
2. Professor, Institute of Construction Materials, Univ. of Stuttgart, Pfaffenwaldring 4, 70560 Stuttgart, Germany (corresponding author).
3. Professor, Dept. of Engineering and Geotechnical, Univ. of Pescara, Viale Pindaro 42, 65127 Pescara, Italy.