Hydrogen and Concrete - Literature review

This work on the interactions of hydrogen with cementitious materials is conducted as a literature survey as a part of the VTT project H2Matters. The goal of this study is to summarize what is known about hydrogen behaviour, transport, and interactions with cementitious material, as well as current modelling capabilities, and highlight knowledge gaps that require further research. Preventing hydrogen leakage from underground hydrogen storage is important for preventing economic, safeguarding from hazard due to hydrogen flammability, and because of the effect of a leakage on the public opinion and acceptance of storage sites. There may be possible, but still unknown effects on atmosphere and climate change, on materials both at the storage facility or other above the ground structures, and on aquifers and biota. Concrete structures will not be the sole barrier of hydrogen, but it is important to minimize the possibility of leaks and safeguard the structural soundness.
The transport of gasses in cementitious materials is governed by the pore structure and saturation state of the material. The research on the effects of hydrogen on cementitious materials is rather scattered and concentrated on oil well cements. In this review it was found that the testing of both the hydrogen transport in cementitious materials and the hydrogen effects on cementitious materials has mostly been studied with a very limited number of binder compositions and most of the research has been done on pastes. Mortar and concrete studies, and studies where actual hydrogen is used, are either scarce or lacking altogether. There are known geochemical effects of hydrogen on rocks, but the possible implications of these studies on mortar/concrete aggregate or binder mineral phases, have not been considered in the published studies found.
Majority of the studies surveyed conclude that the effects of hydrogen on cementitious materials is insignificant, however the test durations are often very short. When planning structures with long service life, even the more subtle changes in the structural and barrier materials should be well understood. This is essential for making sound material and engineering decisions. Both the physical, chemical and thermal environment to which the materials will be exposed in a real-life storage facility have a significant effect on the possible ageing mechanisms. Material research should be done with realistic exposure conditions and on materials with actual compositions considered for these environments.