Why are highways paved with asphalt instead of concrete?

Recently I have seen city roads being overhauled, replacing concrete roads with asphalt. Road construction is particularly important in the construction of modern cities, but in what type of road to repair the argument can be said to be benevolent, wise and wise. So what kind of road is good?

First of all, the cement road (that is: steel road):

The advantages: First, long service life, but if the grass-roots level is not good or with the same ratio of unscientific cracking and other problems, and even large areas of cracking; Second, load-bearing, asphalt pavement is the opposite. Disadvantages: First, it is not easy to maintain; even if you want to destroy will also increase the cost; Second, the noise, affecting the normal life of the public; Third, the panthermal strong, plus the sudden rise in temperature; Fourth, the smoothness is poor; reduce the comfort of driving.

Return to tarmac (i.e.: flexible road):

The shortcomings are: First, short life, but if the grass-roots level is properly handled can also catch up with the use of cement road life, and even more than the use of cement road life; Second, the grip of the tires is strong, but the car is expensive oil (soft pavement resistance), paving, maintenance costs are high; Third, it is easy to aging, the dark pavement is easy to absorb the heat and produce a certain degree of dissolution. The advantages are too much: first, strong heat absorption, low flood heat; second, easy maintenance; third, good leveling; fourth, low noise.

Because China is not a big oil country, so the asphalt production is not high, and China is a big producer of cement, cement cost is low, in the previous years to consider the cost of cement road has been promoted for a period of time, but in the use of a period of time, found that the cement road has a big defect: dust, the road surface is easy to break, the road surface is broken almost can not be repaired. In the large traffic volume, vehicle load capacity of the main road is extremely unsuitable, because of its flatness can not reach, in the construction of highways are rarely used. Now in the eastern economically developed areas are beginning to use tarmac. But cement pavement due to low cost, construction is simple, can be used in the traffic flow is not small, small car type of road.

The original paving tarmac is used to spray paving, poor water permeability, easy to slip on rainy days, hot days and will melt and stick all over the car. Cement roads are expensive, difficult to repair, and slippery when it rains. Now converted to asphalt pavement (highway), is the use of fried mix (like sugar fried chestnuts with asphalt fried gravel) paved, permeable, not easy to slip on rainy days, high temperature, heat will not melt, easy to maintain, with a paver can be paved 12 meters of road surface, easy to mechanize.

Asphalt pavement is generally black, giving people a deep and steady feeling, driving people will feel more collapsed. But the concrete road is the color of off-white, giving people a feeling of insufficient floating air, no landscape can be said. So in the community or municipal main road, secondary road design, want to go up a bit of class, then choose asphalt pavement.