Characterization of Delayed Ettringite Formation in Maryland Bridges

Abstract :-
The research investigated the significance of Delayed Ettringite Formation (DEF) presences in the Maryland Bridge Inventory. The objective of the research included investigating possible presence of DEF, correlations between the presence of DEF in cast-in-place concrete and moist map cracking, and correlations between presence of DEF in cast-in-place concrete and air entrainment agents (AEA). The research required coring a target population, so that scanning electron microscope (SEM) with energy dispersive analysis x-ray (EDAX) could be utilized to identify DEF in the concrete. Combination of visual identification, SEM and elemental identification with EDAX are used to verify the presence of DEF in the concrete samples. The research was conducted in two phases with the first suggesting a possible link between moist map cracking and DEF. The research identified numerous ettringite morphologies in bridge concrete. Characterization of the ettringite morphologies suggested that lamellar ettringite could be linked to DEF-related damage. From this work, a second phase was developed to establish a link between degree of moist map cracking and DEF.

Author:- Ceary, Micah


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