On the Chloride Distribution in Concrete and Mortar Samples after an RCM Test

Area of Science:

• Materials Science
• Civil Engineering
• Durability of Structures

Background:

• Addressing CO2 reduction in cement and concrete production requires reliable performance evaluation methods.
• The rapid chloride migration (RCM) test is standard for assessing concrete's resistance to chloride ingress.
• Discrepancies between RCM test model assumptions and experimental chloride distribution data prompted further investigation.

Purpose of the Study:

• To investigate chloride distribution in concrete and mortar samples post-RCM testing.
• To identify factors influencing chloride extraction, such as time and sample location.
• To compare chloride distribution patterns between concrete and mortar specimens.

Main Methods:

• Performed rapid chloride migration (RCM) tests on concrete and mortar samples.
• Analyzed chloride distribution profiles using drill powder extraction at various times and locations.
• Compared experimental chloride gradients with theoretical model assumptions.

Main Results:

• Concrete samples exhibited an uneven chloride front, lacking the sharp gradient predicted by models.
• Mortar specimens demonstrated a theoretical profile shape, confirming model assumptions.
• Prompt analysis of drill powder from uniform penetration areas in mortar is crucial for validating RCM test models.

Conclusions:

• The RCM test model's assumption of a sharp chloride ingress front is valid for mortar under specific sampling conditions.
• Chloride distribution in concrete is significantly more complex due to an uneven ingress front.
• Careful consideration of sample type and extraction timing is necessary for accurate RCM test data interpretation.