Table of Contents
Introduction:
The rapid chloride permeability test of concrete is an in-situ test to check concrete permeability. This test is very simple and gives results very fast.
Rapid Chloride Permeability test is powered by AASHTO T 277 or ASTM C 1202.
The rapid chloride permeability test of concrete is conducted to check the Concrete’s Ability to Resist Chloride Ion Penetration.
In this test, we check the electrical Indication capacity of concrete to Resist Chloride Ion Penetration. This test enables the prediction of the service life of concrete structures. It can also be utilized for durability-based quality control purposes.
In this test, the steady voltage (V) is applied to a concrete specimen for 6 hours, and the current (i) going through the concrete is recorded to find the coulombs.
What is a coulomb?
As we know, electric Current is measured in amperes. A coulomb is an ampere – second;
which implies 1 ampere passed through the concrete specimen in 1 second is a 1 coulomb, and the charge passed in 60 seconds would be 60 coulombs. The more permeable the concrete, the higher the coulombs; the less porous the concrete, the lower the coulombs.
Apparatus of Rapid Chloride Permeability Test:
This test apparatus comprises two reservoirs. One of them has 3 % of NaCl solution and another reservoir has 0.3 M NaOH Solution, Concrete having a thickness of 50 millimeters and diameter 90 to 100 millimeters is used as a test specimen.
Test Procedure of Rapid Chloride Permeability Test of Concrete:
- The concrete specimen having a diameter of 100 millimeters and thickness of 50 millimeters is cast and saturated.
- The concrete sample is placed in between the two reservoirs having NaCl solution in one reservoir and NaOH solution in the other reservoir.
- These reservoirs are connected to the DC supply and the voltage of 60 Volts is applied to the concrete specimen at both ends for six hours.
- Now measure the current going through the concrete at various time intervals.
- The current going through the concrete is calculated by an LCD which is connected to the cell.
Test Formula:
Rapid Chloride Permeability Test Formula is given in the below figure.
Table for test results:
| Charge (Coulombs) | Chloride Permeability |
|---|---|
| >4000 | High Permeable Concrete |
| 2000 – 4000 | Moderate |
| 1000 – 2000 | Low |
| 100 – 1000 | Very Low |
| <100 | Negligible |