Building materials consisting primarily of limestone and other minerals mixed with water and various additives, used for constructing various structures, such as foundations, walls, and roads.
In the annals of human history, concrete has stood as the sturdy foundation upon which modern society has been built. This ubiquitous substance, often dismissed as plain and uninteresting, has flowed through time, hardening into a myriad of structures that span the ages, from the ancient Roman aqueducts to the iconic Sydney Opera House.
Yet, despite its ancient origins and widespread use—second only to water on Earth—our understanding of concrete continues to evolve. For over a century, researchers at the National Institute of Standards and Technology (NIST) have delved into the intricacies of concrete, their expertise making NIST uniquely equipped to tackle scientific questions about this versatile material and its performance.
Recent research by NIST experts has shed new light on a pervasive issue known as concrete cancer, specifically the Alkali-Silica Reaction (ASR). This unintentional chemical reaction causes concrete to crack, resulting in costly and potentially disastrous consequences for structures.
The ASR produces an expanding gel inside the concrete that presses outward, leading to hairline fractures and yellowish discoloration around cracks. Over time, this damage becomes irreversible and can eventually cause structural failure.
To better understand this reaction and its impact, NIST researchers recreated concrete cancer in laboratory conditions by intentionally introducing reactive aggregates to concrete samples and accelerating the ASR process. They then studied how this reaction weakened the concrete by applying mechanical stress using hydraulic presses, helping to understand the progression of damage and its structural implications.
This work was motivated in part by concerns over safety at significant facilities such as the Seabrook Station Nuclear Power Plant, where early ASR symptoms raised alarm about long-term structural risks. The research is aimed at better understanding these reactions and developing mitigation strategies to prevent the costly and dangerous effects of concrete cracking.
In summary, NIST's recent findings highlight:
- The chemical origin of concrete cracks from ASR producing an expanding gel that fractures concrete.
- The slow but irreversible worsening of the damage over years or decades.
- Experimental methods to accelerate and study the reaction and its impact on concrete strength.
- The practical need to assess and manage these reactions in critical infrastructure to extend lifespan and safety.
As we continue to build our world with this remarkable substance, understanding and addressing issues like concrete cancer will be crucial in ensuring the safety and longevity of our structures. The work of NIST researchers in this area is a testament to the ongoing quest to unlock the secrets of concrete and harness its full potential.
[1] National Institute of Standards and Technology. (n.d.). NIST Research Focuses on Alkali-Silica Reaction (ASR) in Concrete. Retrieved from https://www.nist.gov/news-events/news/2020/09/nist-research-focuses-alkali-silica-reaction-asr-concrete
[2] National Institute of Standards and Technology. (n.d.). NIST Researchers Study Concrete Cancer to Save Billions for State Governments. Retrieved from https://www.nist.gov/news-events/news/2019/05/nist-researchers-study-concrete-cancer-save-billions-state-governments
[3] National Institute of Standards and Technology. (n.d.). Concrete: The Liquid Rock. Retrieved from https://www.nist.gov/science-technology/building-structures-materials/concrete-liquid-rock
[4] National Institute of Standards and Technology. (n.d.). NIST Research Aims to Improve Safety of Seabrook Station Nuclear Power Plant. Retrieved from https://www.nist.gov/news-events/news/2020/06/nist-research-aims-improve-safety-seabrook-station-nuclear-power-plant
In the realm of critical infrastructure, NIST researchers are studying the Alkali-Silica Reaction (ASR) in concrete, a chemical reaction that causes concrete to crack, potentially leading to safety issues and costly consequences for structures. Their research aims to develop mitigation strategies to prevent the effects of concrete cracking, such as those seen at the Seabrook Station Nuclear Power Plant.
In the pursuit of advancements in science and technology, understanding and addressing issues like concrete cancer is essential for ensuring the safety and longevity of medical-condition facilities and other critical infrastructures. The investigations by NIST researchers help increase our knowledge about concrete, contributing to its effective use in a wide range of applications.
