Title:
Proprietary and Carbon Fiber Modified Overlays in the Cathodic Protection of Reinforced Concrete
Author(s):
Rejean J. Brousseau and Glendon B. Pye
Publication:
Materials Journal
Volume:
94
Issue:
4
Appears on pages(s):
306-310
Keywords:
anode; cathodic protection; reinforced concrete; shotcrete; spraying;
titanium mesh;
DOI:
10.14359/313
Date:
7/1/1997
Abstract:
Steel reinforcement corrosion in chloride contaminated concrete is a costly problem that can be mitigated by cathodic protection. A variety of anode systems are currently available for the cathodic protection of reinforced concrete. One of the most effective anode systems is made of a noble metal oxide coated titanium mesh. The titanium mesh is first mechanically fastened on the concrete and subsequently encapsulated with a shotcrete or concrete overlay. This system is performing extremely well on horizontal surfaces. However, delamination of the encapsulating shotcrete overlay has occasionally been observed on vertical surfaces such as piers, columns and walls. The present research project was initiated to address this problem. The performance of three different cementitious overlays (two proprietary and one designed in-house) were investigated under impressed current over a period of 31 months. Samples were polarized outdoors or indoors under constant relative humidity. Numerous performance parameters were monitored on the samples that were energized at three different current densities. The worst performance was obtained with the Thorotop HCR overlay for which high circuit resistance and appreciable increases in the driving voltage were observed. The best overlay for cathodic protection was designed to have maximum adhesion using silica fume, and minimum resistivity by the addition of carbon fibers.