Long-term Hardening Characteristics of Prestressed Anchorage Grout

Grout plays an important role in the transmission and maintenance of anchoring force, and in the protection of anchorage materials against corrosion. Thus, the hardening characteristics of grout directly affect the anchoring effectivity and long-term reliability. We have excavated a prestressed anchorage which has been in service for 20 years, and have tested the grout which has worked for that long period under complicated geological conditions through strength tests and have analyzed its mineral composition using scanning electron microscopy (SEM) and X-ray diffraction (XRD).The results show that the mineral composition of the 12.5 m segment differs from other segments, and corresponds with poor coagulation characteristics of the 12.5 m segment grout. Analysis shows that unhydrated tricalcium silicate may be the reason for the localized poor coagulation.