Why doesn't China use cement (concrete) pavement as widely as the United States?

Our country's highways are developing rapidly, and many new and renovated highways have been built and rebuilt in recent years, which are basically adoptedasphalt pavementAt present, more than 95% of highways are asphalt pavement.

But not all highways are asphalt, and a small number of them doCement pavement。 However, in the early stage of the development of highways in our country, there were many cement pavements. Cement is very cheap compared to asphalt, a ton of cement only costs more than 300 yuan, and a ton of asphalt costs more than 3,000 yuan, which is more than 10 times the price of cement, so why is asphalt pavement gradually replaced with cement pavement?

The use of cement pavement on the highway is not only cheap, cement pavement has high strength, anti-densation, vibration resistance, will not soften under high temperature conditions, long service life, good pavement flatness, this is the biggest advantage of cement, so cement has become the most common building material instead of lime early. In addition, cement is resistant to flooding and erosion, and will not shorten its life in rainy areas. The cement pavement is lighter in color, and the road surface is clear at night.

Compared with cement pavement, asphalt pavement has low strength, and the pavement is easy to soften and become sticky in summer, not resistant to water immersion, not resistant to erosion, and is easy to fall off once cracks appear, resulting in uneven pavement potholes. Asphalt is toxic, especially in the hot summer months and has a pungent smell. It is difficult to see the real situation of the road surface at night, and it is easy to mistakenly enter potholes.

Despite so many advantages and asphalt pavement has so many disadvantages, several fatal disadvantages of cement pavement are also that it has fallen out of favor, at least on highways. Due to its high strength and rigidity, cement has a serious shortage of its own resistance to thermal expansion and contraction, so for the life of the highway, the cement pavement must be set at a certain lengthexpansion jointsto solve the problem of thermal expansion and contraction.

This is like the seamed rails in the past, there will be regular clicking sounds and bumps when the train is running, and now the railway builders have made unremitting efforts to solve the problem of thermal expansion and contraction of the railsSeamless rails。 However, due to the characteristics of cement, it is not possible to solve its thermal expansion and contraction problem well. Highway cars are driving at a high speed of more than 100 kilometers, and the bumps and noise caused by expansion joints greatly reduce comfort.

The existence of expansion joints also destroys the integrity of concrete, and rainwater is easy to penetrate deep into the base, destroying the strength of the highway, piece by pieceConcrete roadParticularly prone to movement and damage. The national highway near my house used to be next to the cement pavement, and after a few years of construction, under the weight of the large truck, the cement pavement broke into large pieces and the base was empty. Later, the entire line was changed to asphalt pavement.

In addition, the cement pavement has high rigidity and lack of elasticity, and the car has high tire noise and poor comfort when driving at high speed. Once cracks appear on the cement pavement, it is difficult to repair and the maintenance cost is high, unlike asphalt pavement, where it is easy to dig out the damaged parts and repair them locally. On the contrary, asphalt pavement has good elasticity, high comfort, and is easy to repair, which can effectively prevent water seepage into the base.

Although asphalt pavement on highways has gradually replaced cement pavement, and more and more national highways and urban roads have also adopted asphalt pavement, not all asphalt has been used instead of cement for road construction, but basically both are used, giving full play to their respective advantages and avoiding their respective disadvantages. Cement is generally used in the base layer, and reinforced concrete is used in highways to improve the strength of the road and extend the life of the road. The combination of the two makes good use of their advantages to make up for the disadvantages and achieves the best cost performance. Not only the highway, but also the airport runway.