INVESTIGATION OF GROUTED PRECAST CONCRETE WALL CONNECTIONS AT SUBFREEZING CONDITIONS

摘要

The effect of exposing grouted precast wall connections to subfreezing curing temperatures at early-age was explored in this study. In cold weather construction, heating of the surrounding environment of grouted precast wall connections is usually conducted for short periods of time. Hence, subfreezing conditions can affect the strength of the grout and the bond strength of the connection, which can ultimately compromise the integrity of the structure. In this study, grout specimens typical of that used in precast wall construction were cured at ambient conditions for one day, and then placed in an environmental chamber at subfreezing temperatures (-10°C and -20°C). The compressive strength development of the grout was monitored, and the bond strength of grouted connections cured at cold temperature were quantified and compared to that of specimens cured at ambient temperature. The bond was investigated on 25M deformed steel bars, which is the typical size used in precast concrete wall grouted connections. Test results indicate a reduction in grout strength and the need for a longer embedment length when early-age curing is conducted at subfreezing conditions.