Chapter 6 Natural Pozzolans Christos Dedeloudis, Monika Zervaki, Kosmas Sideris, Maria Juenger, Natalia Alderete, Siham Kamali-Bernard, Yury Villagrán and Ruben Snellings Abstract This chapter is dedicated to several kinds of natural pozzolans that occur around the globe and describes their specific characteristics, origin and use in concrete. Moreover, the advantages and disadvantages of their use in concrete mixes are highlighted in terms of concrete properties. In particular, the referenced C. Dedeloudis (&)  M. Zervaki Imerys Functional Additives, Andrea Metaxa 15, 14564 Kifissia, Greece e-mail: Christos.dedeloudis@imerys.com M. Zervaki e-mail: Monika.Zervaki@imerys.com K. Sideris Laboratory of Building Materials, Democritus University of Thrace, 12 Vas. Sofias Street, 67100 Xanthi, Greece e-mail: kksider@civil.duth.gr M. Juenger Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, 301 E. Dean Keeton St. C1748, Austin, TX 78712, USA e-mail: mjuenger@mail.utexas.edu N. Alderete  Y. Villagrán Magnel Laboratory for Concrete Research, Ghent University, Tech Lane Ghent Science Park, Campus a, Technologiepark 904, 9052 Zwijnaarde, Belgium e-mail: nataliamariel.alderete@ugent.be Y. Villagrán e-mail: yuryvillagran@conicet.gov.ar N. Alderete  Y. Villagrán Department of Concrete Technology, LEMIT, 52 Entre 121 Y 122 S/N, 1900 La Plata, Buenos Aires, Argentina S. Kamali-Bernard Laboratoire de Génie Civil et Génie Mécanique, INSA-Rennes, 20 Avenue Des Buttes de Coësmes, CS 70839, 35708 Rennes Cedex 7, France e-mail: siham.kamali-bernard@insa-rennes.fr R. Snellings Sustainable Materials Management, Boeretang 200, 2400 Mol, Belgium e-mail: ruben.snellings@vito.be © RILEM 2018 N. De Belie et al. (eds.), Properties of Fresh and Hardened Concrete Containing Supplementary Cementitious Materials, RILEM State-of-the-Art Reports 25, https://doi.org/10.1007/978-3-319-70606-1_6 181