Investigation of the Durability of 52 Year Aged RC Structures Constructed of Portland Blast-furnace Slag Cement Type-C

Abstract

Synopsis: This paper investigated the durability and hydration reaction of a 52-year-old RC structure to clarify the long-term durability of concrete using Portland blast-furnace slag (BFS) cement type C. The concrete was found to have undergone long-term strength development and to still retain calcium hydroxide and unhydrated BFS. Although it was observed that vaterite was produced and pore volume was increased by the carbonation reaction, C-S-H still remained and remarkable decomposition of hydration products, which is often seen in accelerated carbonation tests of concrete, was not observed. From these results, it is concluded that Portland blast-furnace slag cement type C can be applied to concrete structures that require long-term durability.

41 Year Long-Term Durability of High Volume Blast-Furnace Slag Cement Concrete

“…It has been thought that when C-S-H is completely broken down by carbonation, it becomes silica gel and shows a peak at 1080 cm -1 (Wu et al 2016;Wang et al 2018). Sagawa et al (2017) considering the results of FT-IR analysis using an actual concrete structure with blast-furnace slag cement type C that had been exposed to the natural environment for 52 years, where a broad peak at 980-1080 cm -1 due to C-S-H was shown, concluded that the C-S-H in the carbonated region had not completely broken down, but C-S-H with a lowered Ca/Si ratio and sound C-S-H were mixed. Because the results of the present study showed a similar tendency to those of Sagawa et al, it was also presumed that C-S-H had not completely broken down and some C-S-H remained in the concrete with a GGBS replacement ratio of 70% and a material age of 41 years.…”