'Bamboo bridge' with a capacity of 16 tons

A newly built bridge in China with longitudinal beams made of bamboo composite materials has proved to be highly resistant, even for vehicles with a tonnage of 16 tons. With the advantages of being cheap and environmentally friendly in the manufacturing process, bamboo beams have the same bearing capacity as concrete and steel. The person who came up with the idea of ​​making bamboo bridge girders is Professor Yan Xiao from the University of Southern California (USA) and Hunan University (China).

Instead of using fresh bamboos that have been used as construction materials in Asian countries for thousands of years, Xiao devised a way to combine bamboo pieces into beams like wood. Although he did not reveal the details of the bamboo beam manufacturing process, he said the pieces of bamboo were cut from bamboo and re-arranged in several layers and combined with a special glue. Xiao thinks that this technique has never been used to 'cast' large beams.

In mid-December, workers completed the assembly of a 10-meter-long bridge based on Professor Xiao's design in a village in Hunan Province. Using the ' prefabricated ' bamboo bridge beams, the group of 8 workers takes only 1 week to complete the bridge. Xiao said demand was strong enough to withstand the weight of a 16-ton truck, and based on the results of the bridge structure test, it even had higher bearing capacity.

Bridge with bamboo beams in Hunan Province, China.(Photo: Newscientist)

According to Xiao, when being stretched, bamboo is stronger than steel and in a state of being compressed, bamboo is more durable than concrete . Compared to timber trees, bamboo has a much shorter development time, only a few years high, so it is possible to harvest more on the same land area. In addition, since bamboo is a shrub form, when harvested, it can retain the roots to keep growing.

Bamboo bridges can be used for bridges up to 30 meters long, Professor Xiao said, so they are suitable for overpasses in big cities.'I greatly appreciate the work of Professor Xiao, architect Darrel DeBoer, president and founder of DeBoer Architects, one of the ten green-standard architectural firms in the US. DeBoer notes that the cement production process emits a lot of greenhouse gases, carbon dioxide (CO ₂ ), accounting for about 5-10% of global CO2 emissions. Meanwhile, bamboo absorbs CO2 in the development process. 'From an environmental perspective, bamboo is a great choice,' DeBoer said.

DONG NGUYEN