# The Influence of Fly Ash Carbonation on the Protective Properties of Concrete Cover Towards Reinforcement

## TL;DR

This study explores how carbonating fly ash affects concrete's ability to protect steel reinforcement, finding that it can significantly extend the material's service life.

## Contribution

The study introduces a novel approach to using carbonated fly ash in concrete to enhance long-term durability and reduce CO2 emissions.

## Key findings

- Concrete with carbonated fly ash showed a compressive strength reduction of up to 9% after 90 days.
- Carbonated ash reduced the carbonation rate of concrete by about 4% compared to non-carbonated ash.
- Concrete containing carbonated ash had an estimated service life over 20 times longer than reference concrete.

## Abstract

To address the challenge of reducing carbon dioxide emissions, this study focuses on carbon dioxide sequestration in calcareous fly ash and its use in mortar and concrete specimens, including reinforced structures. Calcareous fly ash was used in this study because it contains more reactive Ca phases, enabling efficient CO2 capture and long-term storage through mineral carbonation. The research examines the influence of incorporating carbonated fly ash on the protective properties of the concrete cover for steel reinforcement, along with an analysis of the mechanical behavior of the specimens, resistance to weathering carbonation, and the modeling of the service life of reinforced concrete structures. The results indicate that the compressive strength of concrete specimens decreases with the addition of carbonated ash, though by no more than 9% after 90 days. The carbonation rate of concrete increases with the addition of ash; however, a roughly 4% lower rate was observed for carbonated ash compared to non-carbonated ash. No significant impact of ash carbonation on chloride diffusion or the corrosion process of reinforcement in mortars was detected. As a result, the estimated service life of concrete containing both ash and carbonated ash is over 20 times longer than that of the reference concrete.