Ancient Roman builders achieved extraordinary structural durability in maritime concrete structures, such as piers and breakwaters, by utilizing a specific mix of volcanic ash known as pozzolana. Unlike modern Portland concrete, which degrades when exposed to seawater, Roman concrete undergoes a beneficial chemical reaction upon contact with saline ocean water. Specifically, the seawater dissolves the volcanic crystals and tuffs within the concrete, which subsequently recrystallizes as a rare mineral called aluminous tobermorite. This mineral reinforces the cohesive structure of the concrete over centuries, rather than weakening it. Consequently, instead of eroding, Roman maritime concrete structures actually grow stronger over time when submerged in marine environments.
Based on the text, what is true of Roman maritime concrete when it is exposed to seawater?
- AIt is less durable in marine environments than modern Portland concrete.
- BIt decomposes over time because the salt in seawater gradually erodes the volcanic ash.
- It undergoes a chemical reaction that results in the formation of a mineral that reinforces its structure.Answer
- DIt is formulated to prevent seawater from dissolving its volcanic crystals.