In the quest for sustainable construction materials, alkali-activated mortars (AAMs) have emerged as a promising alternative to traditional ordinary Portland cement (OPC). However, their long-term behavior, particularly regarding steel corrosion, remains a critical area of study. A recent investigation led by Nina Gartner from the Slovenian National Building and Civil Engineering Institute sheds light on this very issue, offering valuable insights for the construction and energy sectors.
Gartner and her team explored the corrosion behavior of steel embedded in three types of AAMs—fly ash, slag, and metakaolin-based—over a year-long period. The study, published in *Case Studies in Construction Materials* (translated as *Case Studies in Building Materials*), employed advanced monitoring techniques to assess the long-term corrosion processes in these alternative binder systems.
The researchers utilized coupled multi-electrode array (CMEA) sensors to measure partial currents and electrical resistance (ER) sensors to track thickness reduction. “The ER sensors allowed us to evaluate general corrosion rates over time, while CMEA provided insight into corrosion initiation and its spatiotemporal distribution,” Gartner explained. This dual approach enabled a comprehensive understanding of the corrosion processes at play.
The study revealed distinct corrosion patterns depending on the precursor material. Metakaolin-based AAMs exhibited severe corrosion, slag-based AAMs showed localized pitting, and fly ash-based AAMs experienced moderate damage. These findings highlight the importance of selecting the appropriate precursor material for specific applications, particularly in the energy sector where infrastructure often demands high durability and resistance to harsh environments.
The researchers also employed X-ray computed microtomography (microCT) to evaluate the corrosion damage on the embedded steel and sensors. This advanced technique provided detailed visual analysis, further enhancing the understanding of the corrosion processes.
The study’s findings have significant implications for the construction and energy sectors. As the demand for sustainable and durable construction materials grows, AAMs present a viable alternative to traditional OPC. However, their long-term performance must be thoroughly understood to ensure their safe and effective use.
Gartner’s research underscores the importance of advanced monitoring techniques in assessing the corrosion behavior of steel in AAMs. “Our study demonstrates the complementary value of CMEA and ER sensors in characterizing the long-term corrosion processes in these alternative binder systems,” she noted. This knowledge is crucial for the development of more durable and sustainable construction materials, ultimately benefiting the energy sector and beyond.
As the construction industry continues to evolve, research like Gartner’s will play a pivotal role in shaping the future of sustainable building practices. By understanding and mitigating the corrosion processes in AAMs, we can pave the way for more resilient and environmentally friendly infrastructure.