Electrical Conductivity Test

Published: April 9, 2019 | Last updated: July 5, 2023

What Does Electrical Conductivity Test Mean?

An electrical conductivity test indicates the amount of soluble ions present in the soil. Electrical conductivity is determined using a conductivity cell that measures the electrical resistance in a 1:5 soil:water suspension. This is one of the tests required for a geotechnical investigation and is used to determine the characteristics of soil in order to arrive at the correct method of trenchless construction.

Geotcehnical test results are important in order to select the right equipment and drilling fluid mix required to carry out pipeline installation successfully.


Trenchlesspedia Explains Electrical Conductivity Test

For the electrical conductivity test, the soil sample is taken at a depth of 0 to 3 inches from different spots along the proposed route. The !:5 soil:water suspension is prepared by weighing 10 gram air-dry soil and adding 50 ml de-ionized water in a bottle. The bottle is shaken mechanically for 1 hour at 15 rpm in order to dissolve soluble salts. The conductivity meter is calibrated to obtain the cell constant. The electrical conductivity is measured at the same temperature as the suspension.

The conductivity cell is rinsed with the soil suspension and refilled without disturbing the settlement. To test another sample the cell should be rinsed with de-ionized water. The Electrical conductivity is measured as:

EC = (S x 1.413) / K, where:

S = measured suspension EC

K = measured solution EC


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