Which risk increases when Roman concrete (opus caementicium) is exposed to seawater for extended periods?

💡 Explanation

When exposed to seawater, Roman concrete undergoes deterioration as sulfate ions penetrate the porous cement matrix, causing expansive reactions that disrupt the concrete’s integrity. Therefore, sulfate attack increases, rather than alkali-silica, rebar corrosion or carbonation, which involve different chemical processes or materials.

• Which observational distortion complicated astronomical calculations performed using astrolabes during the medieval era?
• Which optical effect arises when a medieval lens distorts point light sources due to irregular grinding?
• Which structural problem contributed significantly to the eventual breaching of the Theodosian Walls surrounding Constantinople?
• Which mechanism allowed Roman concrete fortifications to maintain structural integrity in marine environments despite constant wave action?
• Which phenomenon allowed Ibn al-Haytham (Alhazen) to accurately describe image formation in his 'Book of Optics' (Kitab al-Manazir)?
• Which issue arises when inadequate drainage exists alongside a Roman road built on clay-rich soil?