Long-term use of modern Portland cement concrete: The impact of Al-tobermorite formation

The distribution of compressive strength in thick concrete members exposed to various environments in a nuclear power plant undergoing decommissioning is investigated. X-ray diffraction data, scanning electron microscopy analysis, and chemical analysis data reveal that rock-forming minerals in the aggregate had reacted and portlandite had been consumed to form calcium alumino silicate hydrates (C-A-S-H) when evaporable water content was sufficient. In addition, the study confirms Al-tobermorite formation in modern concrete after 16.5 years of elevated temperature conditions ranging from 40 to 55 degrees C. It is concluded that an appropriate aggregate and binder combination for the concrete enhances the compressive strength of thick concrete members thanks to the reaction of rock-forming minerals with portlandite, and also strengthens the chemical stability through the formation of Al-tobermorite under elevated temperature conditions and sufficient evaporable water content. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

The distribution of compressive strength in thick concrete members in a decommissioning nuclear power plant is influenced by the reaction of rock-forming minerals with portlandite. The appropriate aggregate and binder combination enhances the compressive strength and chemical stability of the concrete.