Which mechanism limited Roman concrete structures compared to modern formulations, despite its durability?

💡 Explanation

The absence of steel reinforcement in Roman concrete meant it relied primarily on compressive strength, limiting its ability to withstand tensile stresses and large spans because no tensile support existed, causing cracking under tension. Therefore, tensile load limitations restricted the structures' design, rather than pozzolanic, aggregate, or curing issues, which affected strength differently.

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