About 40 years ago, the rapid development of American industry, more and more cars on the road, tire overcapacity, nowhere to put it, can only be reduced to industrial waste. Considering that the exhaust gas pollution from the collective burning of 2 million tires was too spectacular, the Americans came up with a bad idea to "place" these waste tires on the seabed, and they were not bothered.
2 million tires piled up in the sea, taking up 140,000 square meters of underwater space, the size of 31 football fields. After 40 years, the tires have been soaked in the sea for a long time, producing a large number of toxic substances, wiping out the fish in this area, and even the coral reefs are almost dead.
This practice seriously endangers the marine environment, and the surrounding population is also greatly affected. Fortunately, the United States did not continue to dispose of waste tires in this way of harming others and harming themselves. However, the United States still produces about 300 million waste tires every year, and 85% to 90% of the waste tires are crushed into pieces as derivative fuels. An estimated 650,000 tons of inert tire dust from tire wear enter the environment each year.
A large part is also exported to China and some countries in Africa. Severely damaged waste tires will be sold to small workshops that process rubber pellets, and if they are not seriously damaged, they will flow into the informal tire trading platform through a series of retreading means such as grinding and engraving, and continue to harm people. However, since China banned the import of "foreign garbage", this black industrial chain has not been rampant before.
In 2004, a conscientious civil engineer in the United States saw the environmental pollution caused by tires. I came up with a new way to use used tires to make a roadbed.
His name was Samuel G. Bonasso is a professor of civil engineering at West Virginia University and a registered civil engineer.
Semuel is an experienced civil engineer who has built ski lifts for several U.S. states, has received four patents for modular bridge construction systems, and has extensive experience in road construction. During a traditional road construction project, Semur found that potholes and ruts were common to every road. Especially in places where large vehicles are often crushed, but most of the potholes have only undergone simple repairs, and after repairing, they are still prone to failure, and they cannot be done once and for all.
Inspired by the hive system, he came up with the idea of simply disposing of used tires as skeletons, and then filling the skeleton with rubble or other natural renewable materials to synthesize a building unit that could be used permanently. A subgrade can be formed by neatly arranging multiple building units on roads that need to be built or repaired. After many modeling, laboratory tests and field tests, Semour has put together a complete set of construction processes.
First cut off the upper and lower edges of the tire, leaving only the side circle part, the tire is laid on the road according to the honeycomb structure; directly let the gravel truck pour the gravel into the tire; then manually fill the gap between the tire tires, compaction, and form a complete roadbed; and finally lay a layer of asphalt on the gravel, and the road is repaired. Semuel called this approach mechanical concrete®.
End potholes on the pavement
Potholes are almost all caused by water, which first softens the subgrade material, then causes the ground to crack, produce ruts, and finally sink, accumulating rainwater to form potholes. This method is equivalent to the use of physical gathering and extrusion to fix the stone horizontally and horizontally. Coupled with the use of a single aashto #57s model stone, the porosity and strength make it unaffected by water, even when the pavement is frozen or waterlogged. Use this method to repair potholes, and the location of the potholes will not be damaged again.
Stronger
The traditional asphalt pavement is a flexible pavement, which needs to withstand the extreme vertical deformation and bending deformation of the pavement, and the road surface will be damaged after a long time, and the tire can be added to slow down its bending deformation value. Tests have shown that the roads for laying tires are much stronger than the general roads for direct gravel paving. Each square meter can withstand a load of 150 tons, and trucks over 30 tons will not damage the road. In addition to the strong load carrying capacity, rubber tires also have a certain shock absorption effect.
Fast construction and low cost
The use of mechanical concrete is faster than the construction method of directly using compacted gravel, and some even do not have to lay asphalt layers, and the stones can be used immediately after placing them. Because less equipment, less stone, and less labor are required for construction, construction costs are also 25% to 50% lower than traditional methods.
Low maintenance costs
The road near a new power plant in Fort Morton, USA, uses the mechanical concrete construction method, and nearly 300 coal trucks pass by every day, making the road prone to breakdown. But since switching to this subgrade, the maintenance cost of the road has dropped by 75%.
environmental protection
This brings us back to the scrap tire disposal problem mentioned at the beginning of the article, a 1-mile (1.6 km) road that requires about 12,000 tires. If all 2 million tires dumped in the U.S. were used to build roads, about 192 miles (308 kilometers) of roads could be built. Both the road has been built and the black garbage has been disposed of, killing two birds with one stone, maximizing the use of waste, which is both environmentally friendly and in line with the needs of sustainable development.
Seeing that the mechanical concrete road construction method worked, Semur applied for a patent in 2008 and founded a company to promote this method. At present, this simpler and more powerful way of road construction has been fully developed in the United States industry, and five states in the United States, including Texas and California, are using this method to build roads.
In fact, China used waste tires to build roads as early as the 1980s. However, we process the rubber prototype of the tire into rubber powder particles, and then combine it according to a certain coarse and fine grade ratio, and then add a high polymer modifier, which is fully mixed under high temperature conditions and formed after sufficient swelling with the matrix asphalt.
In fact, the advantages of rubber asphalt are similar to samuel's invention of mechanical concrete. Rubber powder is added to asphalt concrete, and a 5 cm thick road can produce an ordinary pavement of 10 cm thick effect. After adding rubber powder, the viscosity of asphalt is greatly improved, the ability to resist deformation is enhanced, and there is better water resistance, and the noise is also much smaller; the service life is also 1 to 3 times longer than that of ordinary asphalt pavement; it can effectively solve the problem of domestic waste tire pollution.
Some highways in China use rubber asphalt, the "Longbai Rubber Asphalt Expressway" that runs through Yunnan and Guizhou, the "Heda Expressway" that runs through the three eastern provinces, and some urban roads in Changsha, Wuxi, Weifang and other cities use rubber asphalt.
Although the technology looks powerful, it has not yet been used on a large scale in the United States, and the patented technology was only patented in Canada in 2013 and has not yet been promoted globally. Moreover, this construction method is obviously not suitable for use on highways, but more suitable for country lanes.
Brother Lightning speculated that the reason why China does not use this way to pave the way is mainly because China's development speed is too fast. The needs of urban construction will change every year, and it may be necessary to repair the subway this year and the pipeline next year. Once a part of the mechanical concrete subgrade is damaged, the tightness and solidity of the remaining part will be greatly reduced, which may cause the paralysis of the entire road surface and cause greater losses.
Why don't you think China just uses tires to build roads? Feel free to leave your insights in the comments section.