Which structural issue primarily limited the height of Roman defensive walls before the widespread use of concrete?

💡 Explanation

Before concrete, Roman walls used layered stone or brick, dry-laid or with weak mortar. When height increased, lateral forces from wind or earth pressure caused wall bulging due to the limited tensile strength. Therefore bulging resulted, rather than settling, compression, or thermal expansion which are secondary effects.

• Which agricultural outcome benefited pre-Columbian maize cultivation within terrace systems?
• Which outcome occurs when pre-Columbian chinampas agriculture experiences prolonged drought conditions?
• Which consequence results when a brass astrolabe's alidade warps due to uneven heating during daytime use?
• Which risk increased when 18th-century shipbuilders transitioned from predominantly frame-first to hull-first methods?
• Which ecological impact resulted from the intensification of chinampa agriculture in pre-Columbian Mesoamerica?
• Which simplification was enabled by the introduction of symbolic algebra during the Islamic Golden Age in astronomical calculations?