In this study, a fixed load was applied to the PC girder affected by the alkali-silica reaction, and the deflection was measured to evaluate the load-bearing performance. The loading tests were performed on three PC girders in total: a healthy girder, a girder undergoing deterioration due to alkali-silica reaction, and a girder where deterioration had converged.
It is known that concrete deteriorated by alkali-silica reaction has a significant decrease in static elastic modulus. Therefore, after the loading test, cylindrical cores were taken and the compressive strength and static elastic modulus were also investigated at the same time.
As a result, it was confirmed that the compressive strength and static elastic modulus tended to decrease due to the influence of the alkali-silica reaction. In particular, the static elastic modulus showed a tendency to decrease by about 50% compared to when the structure was in a healthy condition.
In general, PC girders whose static elastic modulus has decreased due to alkali-silica reaction will definitely exhibit a larger deflection amount in a load test compared to healthy girders. However, the amount of deflection obtained did not change regardless of the progress of the alkali-silica reaction.
The coarse aggregate used in the PC girder has a characteristic that when it is affected by alkali-silica reaction, many cracks occur inside the coarse aggregate as the coarse aggregate expands. If a load is applied to concrete in this state, there is a high possibility that it will break. However, in the case of PC girders, the rigidity of the girders themselves is high due to the application of prestress. It has also been confirmed that the expansion of coarse aggregate due to alkali-silica reaction causes slight changes in the shape of PC beams and at the same time increases the amount of prestress in the PC steel. It was thought that such effects might result in no change in the amount of deflection measured by the load test.
The authors have so far been conducting research into the propagation of broadband ultrasonic waves through concrete under stress, and the evaluation of the static elastic modulus using the obtained propagation characteristics. In this study, broadband ultrasound was used to clarify the propagation characteristics before and after loading, evaluate the apparent static elastic modulus, and evaluate the load-bearing performance of the PC girder.