About a third of Ming-era walls have disappeared in the past 500 years; the remaining parts are held together by “living” cement, as research has shown.
The Great Wall of China, with its characteristic high brick walls and ramparts, was built in the Ming region between 1368 and 1644. IFLScience writes that during construction, workers often use rammed earth (soil, gravel and other natural materials) as building materials.
About 30% of the Ming walls have collapsed over the past 500 years, but much of the structure still stands. In a new study, scientists sought to find out exactly what holds up much of the Great Wall of China.
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The results of the scientists’ work were quite surprising: it turned out that the Great Wall of China managed to remain standing thanks to the so-called “living” cement. The fact is that the use of soil as a building material contributed to the emergence of the “living” part of the wall. This allowed cyanobacteria, mosses and lichens to grow there, and according to the researchers, it was they who provided wall stability in the form of the so-called “biocrust”.
In the study, scientists collected samples from 8 sections of the Ming-era wall and found that 67% of them contained biocrust. They also compared the mechanical strength and soil stability of biocrust samples with samples composed of simple compacted soil.
The results show that it is the biological shells that give the wall its impressive stability. Compared to empty compacted soil, biocrust-covered areas reduced porosity, water retention capacity, erosion and salinity by 2-48%, according to the team. At the same time, the compressive strength, penetration resistance, shear strength and overall stability were 37-321% higher.
At the same time, scientists realized that the strength also depends largely on the biocrust composition and the climate of the region where the samples were taken. For example, in the driest regions the dominant species in the composition was cyanobacteria, while in wetter conditions algae were dominant. The results also show that moss-dominated shells have the highest strength and stability, significantly reducing wall erosion.
The authors of the study suggest that biocrusts increased the stability and strength of the Great Wall by releasing substances that bind to compacted soil and form a cement-like structure. As a result, this “living” cement helps mitigate the effects of climate change, such as wind, rain and temperature changes.
Previously Focus He wrote that the Great Wall of China was built on rice porridge.
Source: Focus
Ashley Fitzgerald is an accomplished journalist in the field of technology. She currently works as a writer at 24 news breaker. With a deep understanding of the latest technology developments, Ashley’s writing provides readers with insightful analysis and unique perspectives on the industry.