Effects of Fly Ash on Mechanical Properties of PC Girder Using Reac-tive Andesite Aggregates

抄録

In the Hokuriku region, alkali-silica reaction (ASR) caused severe degradations in many concrete bridges. However, criteria for repair and replacement works of these structures are still unclear. For the development of damage evalua-tion procedure, it is necessary to investigate the load-carrying capacity of prestressed concrete (PC) girders affected by ASR-induced deterioration in actuality. This study constructed two full-size PC specimens from the high-early-strength Portland cement and reactive aggregates, and then exposed them to outdoor environmental conditions. One of them was specially mixed with a controlled amount of fly ash. After one and a half years of outdoor exposure, destructive loading tests were carried out to investigate the difference in loading capacity of the girders. From results of the long-term exposure and the tests, the flexural strength and the rigidity of the specimen with fly ash were not degraded while ASR was also effectively suppressed. In addition, cylindrical concrete cores were taken at different positions of both girders to analyze the relationship between mechanical properties of concrete such as compressive strength, static elastic modulus, and ultrasonic wave propagation speed. Results of the coring test showed that the mechanical properties of concrete cores varied according to their collecting positions and directions.