ERE Probe

ERE-Probe

Purpose

The ERE-Probe is a reference half-cell that is embedded in concrete and can be used to:

• Monitor the reinforcement potentials in critical areas for corrosion such as construction joints, splash zones in marine structures, bridge decks, and bottoms of bridge columns exposed to ingress of chlorides
• Monitor the efficiency of cathodic protection
• Monitor the ingress of the depassivation front, due to chloride penetration or carbonation, in combination with installing the CorroWatch

Principle

The ERE-Probe (Embeddable Reference Electrode) is a stable, long life reference electrode for monitoring the half -cell potential of reinforcement. It is based on a manganese dioxide electrode in a steel housing with a chloride-free, alkaline gel and having a porous cement plug at one end. The housing is made from a corrosion resistant material. Diffusion of ions through the porous cement plug is low because the pH of the alkaline gel corresponds to that of pore water in normal concrete. The diameter of the ERE-Probe is 20 mm and the length is 85 mm
In new structures, the ERE-Probe is attached to the reinforcement by plastic straps before placement of the concrete. In existing structures, a hole is drilled to the required depth and the ERE-Probe is embedded using an appropriate mortar. A high impedance voltmeter is used to measure the half-cell potential between the probe and the reinforcement.

Accuracy and Variation

At 23 ºC in a saturated Ca(OH)2 solution, the potential of the ERE-Probe is +160 mV ±20 mV versus a saturated calomel electrode (SCE). The in-place operating temperature is from 0 C to +40 ºC.

Over a long period of time, the variation of each ERE-Probe is within ±5 mV compared with the initial value at the same temperature and for the same electrolyte environment. The expected life time is 100 years.

Testing Example

The ERE-Probe attached to reinforcement before placing concrete

ERE-Probe Ordering Numbers

The ERE-Probe comes with a calibration certificate stating the potential value measured at 23 C in a saturated Ca(OH)2 solution versus a saturated calomel electrode (SCE).