During the match casting operations of precast segments for segmental post-tensioned concrete box girder bridges, a problem can arise due to the heat of hydration of the newly cast segment. When the segments have a particularly high ratio of wing span to segment length, warping of the match cast segment can occur due to a thermal gradient that is caused by the high temperatures in the adjacent newly cast concrete. This warping, or bowing, has subsequently caused problems during erection operations. This paper presents the results of a field study of this phenomenon. Concrete temperatures and segment deformations measured during the casting of several segments for the San Antonio "Y" project are reported along with observations from the erection operations. A simple method is presented to determine whether, for a given bridge, measures to reduce the thermal gradient during match casting should be taken.
