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Some Roman concrete has stood in seawater for nearly 2,000 years, and recent research suggests certain Roman mixes could seal their own small cracks.

MIT study, Science Advances, 2023

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Roman builders mixed lime with rubble and volcanic ash, often from around Pozzuoli near Naples. In 2017 a team led by the geologist Marie Jackson showed that seawater seeping through Roman harbour walls slowly grows new minerals inside them, binding the concrete more tightly over time. A 2023 study led by Admir Masic at MIT examined the small white lumps of lime in Roman concrete, long dismissed as a sign of careless mixing, and concluded that they come from mixing with quicklime while hot. When water later seeps into a crack, it dissolves some of this lime, which crystallises again and can fill the gap. Having no steel bars to rust, Roman concrete also escapes a main cause of decay in modern concrete. The Pantheon's dome in Rome, nearly 1,900 years old, is still the largest unreinforced concrete dome in the world.

Türkçe oku
Bazı Roma betonları yaklaşık 2.000 yıldır deniz suyunun içinde ayakta duruyor. Son araştırmalar, kimi Roma karışımlarının küçük çatlaklarını kendi kendine kapatabildiğini düşündürüyor.
MIT araştırması, Science Advances, 2023

Romalı ustalar kireci moloz taşla ve çoğu zaman Napoli yakınlarındaki Pozzuoli çevresinden gelen volkanik külle karıştırırdı. 2017'de jeolog Marie Jackson'ın yönettiği bir ekip, Roma liman duvarlarına sızan deniz suyunun beton içinde zamanla yeni mineraller oluşturduğunu ve betonu giderek daha sıkı bağladığını gösterdi. MIT'den Admir Masic'in yönettiği 2023 tarihli bir çalışma ise Roma betonundaki küçük beyaz kireç topaklarını inceledi. Uzun süre özensiz karıştırmanın izi sayılan bu topakların, sönmemiş kirecin sıcakken karıştırılmasından kaldığı sonucuna vardı. Bir çatlağa sızan su bu kirecin bir kısmını çözer; kireç yeniden kristalleşerek çatlağı doldurabilir. Paslanacak çelik donatısı olmayan Roma betonu, modern betonun bozulmasının başlıca nedenlerinden birinden de uzak kalır. Roma'daki Pantheon'un yaklaşık 1.900 yıllık kubbesi, bugün hâlâ dünyanın donatısız en büyük beton kubbesidir.

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