Alkali silica reaction: A view from the nanoscale

Understanding the formation of Alkali-silica reaction gel (ASR gel) and its behavior in cement pore network solutions is the key to mitigate one of the main causes of the strength retrogression of concrete. We herein propose a scenario to explain how ASR formation in cement pores can damage the cement paste structure that is supported by state-of-the-art atomistic simulations. We show the formation of an ASR gel at the atomic scale and how the drying or calcification affects its structure and strength. Moreover, we demonstrate that the alkali ions that are released during calcification are attracted by the gel and remain in its vicinity. The high concentration of ions in the solution modifies the interaction of the ASR gel with the cement pore walls and can lead to concrete damage.