Sensor for oxygen evaluation in concrete

This paper includes results from a research work carried out for developing and optimising a sensor to measure the limiting current of oxygen reduction in concrete. Platinum, stainless steel and carbon steel materials were tested as working electrodes in saturated Ca(OH)2 solution. Linear correlations were obtained between the limiting currents of oxygen reduction and the oxygen concentration in solution. The measurements of the limiting current density due to oxygen reduction have been made in concrete specimens with a sensor consisting of platinum and stainless steel, as working electrodes, graphite, as a counter electrode, and activated titanium, as a reference electrode, under different conditions of water and oxygen accessibility to the concrete. The results show that this sensor detects oxygen content variations in the interstitial solution of the concrete, providing qualitative information about the evolution of oxygen availability in concrete. (c) 2006 Elsevier Ltd. All rights reserved.