The reason is that cement solidified graded macadam is selected for the water-stable layer, and the purpose of engineering maintenance is achieved by compaction. The principle of action is to choose graded macadam as aggregate, and when filling the gap of aggregate, you can choose the corresponding amount of cementing material and mortar, and pave and compact according to the principle of embedding and squeezing. Its compactness and compactness are similar, and the principle of interlocking between gravels is the basis of strength growth.