This study evaluates flash metakaolin geopolymer as an effective binder to replace Portland cement in concrete. A study conducted on the workability of fresh geopolymer concretes has revealed that several applications can be targeted, from fluid to dry concretes: reinforced beam or masonry units directly manufactured in industrial precast plant. Compressive strength of geopolymer concretes showed that these materials could have better mechanical properties than Portland cement concretes, despite a larger porosity. The amount of aggregates (in the range 71-83%) seemed to have a negligible effect on the performance of geopolymer concrete, probably due to the absence of ITZ at the binder-aggregate interface. (C) 2016 Elsevier Ltd. All rights reserved.