Carbonation Test

Ensure the durability and safety of your concrete structures with Eurofins Spectro’s specialized Carbonation Testing services. Carbonation is a critical process in which carbon dioxide (CO₂) from the atmosphere reacts with concrete, potentially compromising its structural integrity and increasing the risk of reinforcement corrosion. Understanding carbonation depth is vital for assessing the longevity and safety of concrete infrastructure. Our expert testing services provide precise and reliable results, empowering you to make informed decisions for maintenance and repair.

Why is Carbonation Testing Important?

Carbonation is a natural process where atmospheric CO₂ diffuses through the porous surface of concrete and reacts with calcium hydroxide [Ca(OH)₂] in the concrete pores to form calcium carbonate (CaCO₃). This reaction leads to a reduction in pH levels from 12.5-13.5 to around 8-9, diminishing the concrete’s alkalinity. This reduced alkalinity compromises the passivation layer protecting the steel reinforcement, making it susceptible to corrosion.

Effects of Carbonation

1. Corrosion Risk: A drop in pH below 10-11 dissolves the steel’s passivation layer, creating conditions for corrosion. Fully carbonated concrete with a pH of approximately 7 significantly increases the risk.
2. Structural Integrity: While carbonation slightly enhances the mechanical strength of concrete, it reduces alkalinity essential for corrosion prevention.
3. Durability Impact: Increased water/cement ratios, high permeability, or insufficient cover depth accelerate carbonation, affecting the durability of the structure.

Our Testing Approach

We determine the carbonation depth in hardened concrete using the Phenolphthalein Method, a proven technique for reliable assessment. This method involves applying a phenolphthalein indicator to the concrete surface:

• Above pH 9: The indicator turns red-purple, indicating sufficient alkalinity.
• Below pH 9: No colour change is observed, signalling carbonation.

The phenolphthalein test is ideal for laboratory or on-site testing of cores, fragments, or specimens removed from hardened concrete. However, it is unsuitable for concrete made with calcium aluminate cement.

Purple color indicates Un-Carbonated concrete and colorless Concrete is a Carbonated Concrete

Key Features of Our Carbonation Testing Services

• Accurate measurement of carbonation depth near the surface of hardened concrete.
• Identification of areas at risk of reinforcement corrosion.
• Tailored testing solutions for site-specific or laboratory requirements.

Applications

• Assessment of existing concrete structures for carbonation effects.
• Maintenance planning for buildings, bridges, and other infrastructure.
• Quality control during construction or repair projects.

Get in Touch

Contact our experts today to learn more about our services and how we can support your project’s success.