Delayed ettringite formation in Swedish concrete railroad ties

摘要

A petrographic examination of cracked Swedish concrete railroad ties identified delayed ettringite formation (DBF) as the damaging mechanism. This was unexpected because the concrete railroad ties were steam-cured with a maximum concrete temperature below 60 deg C.The consensus in the published literature is that DEF only occurs in concrete subjected to heat curing above 70 deg C. However, DEF is not only influenced by the curing temperature, but also by various other factors, such as cement composition (alkalis, C_3S. C_3A, SO_3, and MgO), fineness, etc. If an unfavorable combination of these parameters exists, delayed ettringite may occur at lower temperatures than 70 deg C.In this paper, the influence of various parameters on DEF is discussed with reference to the investigated concrete.