The authors mention that "Geopolymer is a sustainable alternative to OPC which emits at least 80% less CO2 and requires about 60% less energy as compared to production of OPC". The authors make wrong assumptions on the contribution of OPC to world’s greenhouse gas emissions because they forget the contribution of carbon storage in OPC structures. Pade and Guimaraes (2007) estimate that for a 100 years life concrete structures can store around 28% of CO2 during 70 years life time and as much as 58% after demolition during 30 years. And a very recent study by Xi et al. (2016) showed that “a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO2 emissions from production of cement over the same period”. Also its far from truth that geopolymers are a low carbon technology, Turner & Collins (2013) prove that, Ouellet-Plamondon and Habert (2014) showed that only ´one part geopolymers` shows carbon footprint levels much lower than Portland cement based mixtures. Also Provis et al. (2015) already emphasized that geopolymers “are not intrinsically or fundamentally ‘low-CO2’ unless designed effectively to achieve such performance”. Recently The et al. (2017) confirmed this. Ouellet-Plamondon, C. ; Habert, G. (2014) Life cycle analysis (LCA) of alkali-activated cements and concretes. In Handbook of Alkali-Activated Cements, Mortars and Concretes, 663-686 (Eds) Pacheco-Torgal, F.; Labrincha, J.; Palomo, A.; Leonelli, C.; Chindaprasirt, P., WoodHead Publishing-Elsevier, Cambridge Pade, C.; M. Guimaraes, M. (2007) The CO2 uptake of concrete in a 100 year perspective. Cem. Concr. Res. 37, 1348–1356. Provis, J.L.; Palomo, A.; Shi, C. (2015) Advances in understanding alkali-activated materials. Cement and Concrete Research 78: 110-125. The, S.; Wiedmann, T.; Castel, A.; de Burgh, J. (2017) Hybrid life cycle assessment of greenhouse gas emissions from cement, concrete and geopolymer concrete in Australia. Journal of Cleaner Production 152, 312-320. Tuner, L.; Collins, F., Carbon dioxide equivalent (CO2-e) emissions: A comparison between geopolymer and OPC cement concrete. Construction and Building Materials 43 (2013) 125–130. Xi et al. (2016) Substantial global carbon uptake by cement carbonation. Nature Geoscience 9, 880-883.