Title: Effect of Early-Age Cracking on Corrosion Initiation in Reinforced Concrete

Author(s): James D. Lafikes, David Darwin, Matthew O’Reilly, and Omid Farshadfar

Publication: Web Session

Volume: ws_S18_SettlementCracking_Lafikes.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 11/16/2018

Abstract:
Many factors-such as concrete slump, compressive strength, and evaporation rate affect the tendency of concrete to crack. While good construction practices can minimize cracking, the vast majority of flat reinforced concrete structures, such as bridge decks, will develop some degree of cracking, which can lead to early corrosion initiation, durability issues, and rapid deterioration. The majority of these cracks are small-less than 0.01 in. (0.25 mm) in width, and there is some debate about the impact cracks of this size have on the service life of structures, particularly with respect to initiation of corrosion on the reinforcing steel in concrete. Laboratory specimens evaluating corrosion in cracked specimens do exist; however, the cracks in these specimens are usually artificially created (typically with stainless steel shims extending to the level of reinforcing steel) and are wider than 0.01 in. (0.25 mm), sometimes significantly so. This presentation will describe the creation of a settlement cracking test capable of inducing cracks as small as 0.001 in. (0.025 mm) in width over the surface of a reinforcing bar. Initial corrosion initiation tests show early corrosion initiation in specimens with maximum crack widths as small as 0.002 in. (0.05 mm), suggesting that even narrow cracks are potentially detrimental to service life.