Resistivity Meter (Resi)
One of the major problems facing an engineer today is deterioration of concrete member by corrosion of rebars. So it is prime concern to determine the state of corrosion in the bars. For this several commercial equipment are available, one of these commercial equipment available is Resistivity Meter (RESI). It is portable equipment and can be easily operated.
RESI consists of a display unit and resistivity probe as shown in Fig. Display unit consists of memory of 7200 values and power is supplied to the unit with the help of batteries. Resistivity probe is available with integrated electronics for the measurements by four-point method. In this method resistivity probe is connected with the display unit to obtain brief display. All the functions are tested and checked before starting the measurement process. After checking, unit probe is placed on the area to be measured. Measurement can be done with grid to represent the resistivity value for a large area. The grid of suitable size is marked on the surface and measurements are taken. There are various factors which affect the observations such as moisture content, carbonation and chloride contents, temperature, connection between probe and concrete.
For taking reliable measurements good contact between the foam pad of the resistivity probe and the concrete surface is essential. Though resistivity meter is used to monitor corrosion but if this technique is used with half-cell potential measurements, it will give more accurate results and corroded zone can be monitored more efficiently.
Application: It is used to monitor corrosion in the steel bars by measuring the concrete resistivity.
