• Purchasing Notes
• Applications
• Features & Benefits
• Product Information
• Specifications
• Downloadable Document (PDF)
  

Gecor 6™

A unique patented field system for measuring the rate of corrosion and other parameters of reinforcement bars.

Purchasing Notes

• We recommend the R-C-3100 R-Meter Complete System™ for locating and analyzing the rebar under test.
  

Applications

• Corrosion Rate Analysis

• Structure Service Life Analysis

• Repair Cost Estimation

Features & Benefits

• The U.S.Strategic Highway Research Program (SHRP) describes the system as giving the corrosion rate most closely matching the true values.

• The system gives important complementary measurements for the interpretation of corrosion rate results.

• The 'A' sensor measures the corrosion rate and half cell potential.

• The 'B'� sensor measures concrete resistivity, ambient temperature and relative humidity.

• Corrosion rate measurement time is 2-5 minutes and up to 100 readings can be stored in the memory for later downloading to a PC.

• Weighing only 9 lbs. the system is easy to use, portable, and menu driven.

Product Information

The Gecor 6™ utilizes the polarization resistance technique to establish the corrosion rate.

This is a quantitative measure of the amount of steel oxidizing at the time of measurement. Up to 100 readings can be stored in memory for later uploading to a Personal Computer. Relative humidity, temperature, half-cell potentials and concrete resistivity also can be measured. Weighing only nine pounds, the system is easy to use, portable and menu driven.

To view videos on the Gecor 6 unit, click on the link below.

• Gecor 6 Operation (see video)
  

• Preparing Rebar for Electrical Connection (see video)

• Gecor Sensor Preparation Video (see video)

Measuring the corrosion of reinforcement bars polarization technique

Rebar Corrosion and its effects:

Corrosion of reinforcement concrete affects the safety and durability of concrete structures in the following ways:

1. The steel cross section is reduced, weakening the structure.

2. The concrete is cracked due to the volume increase in rust.

3. The steel to concrete bond is reduced when cracking and spalling are initiated.

Corrosion is worsened where there is low concrete cover over the steel, high relative humidity and increased moisture present.

Corrosion Rate:

A true measure of the corrosion rate is possible using the polarization resistance technique. It has been well established in the laboratory by Stern and Geary that corrosion current is linearly related to polarization resistance.

Over a period of four years Gecor 6™ was developed by several research organizations. The polarization resistance is measured with a central reference electrode, surrounded by an external counter electrode. A unique guard ring and external electrode system confines the area of the rebar tested. This makes the Gecor 6™ the only field method for determining polarization resistance that is verifiable with proven laboratory techniques.

Gecor 6™ gives the corrosion rate (Icorr) which is a quantitative measurement of the amount of steel turning into oxide at the time of measurement. The current can be converted into metal section loss by Faraday’s Equation.

Corrosion rate values measured by Gecor 6™ give precise information on the risk of corrosion and the following broad criteria have been established:

Icorr <0.2µA/cm² Passive condition
Icorr 0.2 to 0.5µA/cm² Low corrosion
Icorr 0.5 to 1.0µA/cm² Moderate corrosion
Icorr >1µA/cm² High corrosion rate

Corrosion rate measurements with Gecor 6™ should be taken at strategic locations. Other data such as chloride concentration, carbonation depths or half cell potentials and resistivity that can also be measured with Gecor 6™, should be considered.

Corrosion rates vary during the life of the structure, depending on the variations in the concrete moisture content, the chloride concentration and the temperature. Measurements at different intervals should be carried out in order to get average Icorr values.

Complimentary Measurements:

Corrosion potentials can be taken, and interpreted to give a probability of corrosion. However, these half cell potential values do not give precise information on the risk of corrosion. A direct relationship between corrosion rate and corrosion potential has not been established.

Concrete resistivity of the area around the sensor is defined from the formula:

RESISTIVITY = 2 x R x D

Where R is the resistance of a pulse between the sensor electrode and the rebar network, and D is the electrode diameter of sensor B.

Concrete resistivity measured by Gecor 6™ is useful in the interpretation of corrosion rate because it is related to the moisture content.

>100 to 200k cm Very low corrosion rate even with high chloride concentration or carbonation.
50-100k cm Low corrosion rate
10-50k cm Moderate to high corrosion rate where steel is active
<10k cm Resistivity is not the controlling parameter of the corrosion rate

Since the rate of oxidation is directly related to the amount of heat energy available, temperature has a direct effect on corrosion rate. Relative humidity decreases with increasing temperature, and resistivity increases with increasing temperature.

Relative humidity influences the amount of moisture in the pores of the concrete to sustain the corrosion reaction as well as water run off, dew formation, etc.

Specifications

The meter with 'A' sensor will measure and store:

• Corrosion rate (Stern & Geary law).

• Corrosion potential

• Concrete Polarization Resistance

• Date, time and location of reading

The meter with "B"� sensor will measure and store:

• Concrete resistivity

• Relative humidity

• Temperature (°C)

Downloadable Document

• Gecor6_Complete_Data.pdf