Passage
For centuries, materials scientists have marveled at the durability of ancient Roman concrete, which has survived for two millennia in harsh marine environments where modern concrete degrades in decades. A key breakthrough came when researchers analyzed the mineralogical composition of mortar samples from the ancient harbor of Caesarea. They discovered the presence of a rare mineral, aluminous tobermorite, which crystallizes within the concrete. The researchers hypothesized that this crystallization process is actively triggered by the percolation of seawater through the concrete's pores. Rather than damaging the structure, the mineral growth reinforces it over time, filling microscopic cracks and increasing the concrete's overall tensile strength. To support this claim, scientists conducted laboratory simulations exposing Roman-style volcanic ash mortar to saline solutions. Over several months, they observed a significant increase in the concentration of tobermorite crystals alongside a measurable decrease in mortar permeability. This finding suggests that the ancient builders intentionally designed a material that relies on environmental interactions to achieve long-term structural integrity.
Question
Based on the passage, match each of the researchers' claims about ancient Roman concrete with the specific evidence or findings used to support it.
- Seawater exposure actively drives the mineral crystallization process.In laboratory tests, volcanic ash mortar exposed to salt water showed increased crystal growth and lower permeability.
- The growth of aluminous tobermorite increases the concrete's durability.Mineral growth fills microscopic cracks and enhances the concrete's tensile strength.
- Ancient Roman engineers intentionally developed a material that utilizes environmental factors.Mortar samples from the Caesarea harbor contained a rare mineral that forms within the concrete.