2017 Volume 73 Issue 3 Pages 251-270
Recently, fly ash, which is a byproduct from burning pulverized coal in coal-fired power plants, has been used to improve a durability of concrete structures in Okinawa Prefecture. Especially, the superstructure and substructure of Irabu bridge, which has been in service since January 2015, was constructed by using fly ash concrete in order to achieve the durable more than 100 years.
This paper showed results of durability investigations on fly ash concrete (FAC) which a part of fine aggregate was replaced by non-JIS fly ash exposed to the coastline in northern Okinawa Main Island for about 11 years.
It was found from the results that FAC reduces the chloride permeability of concrete, natural current method and polarization resistance method can diagnose the corrosion levels of reinforcing bar in FAC and normal concrete (BC) specimens using the same criteria, and progress of carbonation does not affect to corrosion of reinforcing bar in FAC and BC specimens under a coastal area with high humidity.
Also, from petrological diagnosis on a concrete core taken from BC specimen, it was revealed that ASR is not the main cause of the cracks observed on the surface of specimens.
