Cathodic Protection Current Accelerates the Alkali-Silica Reaction


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Title: Cathodic Protection Current Accelerates the Alkali-Silica Reaction

Author(s): Mohammad Golam Ali

Publication: Materials Journal

Volume: 90

Issue: 3

Appears on pages(s): 247-252

Keywords: alkali-silica reaction; cathodic protection; corrosion; reinforcing steels; reinforced concrete; Materials Research

Date: 5/1/1993

Results from a study on the effect of cathodic protection (CP) current on the enhancement of alkali-silica reaction are presented. Steel embedded in mortar specimens made of high-alkali cement and reactive crushed Pyrex glass were subjected to 215 and 1076 ma/m 2 (20 and 100 ma/ft 2) cathodic protection current at the steel surface. It is observed that CP current densities of 215 and 1076 ma/m 2 (based on the reinforcing steel surface area) advanced the cracking time by 40 and 60 percent, respectively, compared to cracking time in specimens that were not current-treated. There were 34 and 15 percent reductions in compressive strength due to increased alkali-silica reaction when the specimens were exposed to 1076 and 215 ma/m 2, respectively, for 80 days. Hardness of mortar adjacent to the steel is reduced with increase in current densities at the steel surface. It was also found that CP current has no effect on the tensile strength and ductility of low-strength reinforcing steel in concrete. Results obtained from a simple staining technique suggested the formation of higher alkali-silica gel contents near the steel at a higher current density.