Effect of Cracking and Accelerated Curing on the Corrosion of Steel Embedded in High Performance Concretes Exposed to an Industrial Effluent

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Title: Effect of Cracking and Accelerated Curing on the Corrosion of Steel Embedded in High Performance Concretes Exposed to an Industrial Effluent

Author(s): T. Thuresson, C. M. Hansson, P. T. Seabrook and M. Tullmin

Publication: Special Publication

Volume: 170

Issue:

Appears on pages(s): 965-1006

Keywords: Accelerated curing; chlorides; concretes; corrosion; high-performance concretes; precast concrete; silica fume.

Date: 7/1/1997

Abstract:
High Performance Concrete (HPC) has been developed primarily for its strength having a compressive strength in excess of 70 MPa, approximately double the strength of conventional concrete. The porosity of this type of concrete, especially when silica fume is added to the mix, much lower than conventional mixes. It is, therefore, assumed that high performance concrete provides significantly better protection against corrosion of reinforcing steel than conventional concrete, but this has not yet been substantiated. A field exposure program is underway with cast-in-place and pre-cast samples, containing embedded reinforcing steel probes exposed to pulp & paper industry effluent at two locations on Vancouver Island, B.C., Canada. The cast-in-place samples were loaded in three-point bending prior to exposure to initiate cracks in the location of the corrosion probes. Probes were also embedded in uncracked areas of the beams. One lower quality concrete, one industrial standard concrete, one HPC and one HPC containing silica fume were included in the test matrix. Parallel laboratory corrosion studies are being conducted on cast-in-place specimens exposed to a simulated effluent. The initial results of the field exposure showing the difference in corrosion protection of reinforcing steel in the four different types of concrete subjected to accelerated curing and conventionally cured are presented. Laboratory results investigating the effect of cracking on the corrosion protection provided by the four types of concrete are also presented. The reinforcing steel corrosion was evaluated using linear polarization resistance (LPR) and the more recently developed electrochemical noise measurement technology. The suitability of these techniques to measure and monitor the corrosion of reinforcing steel in concrete is also discussed.