(1) Unreasonable mix ratio and poor gravel gradation.(2) The surface of the formwork is rough or the cement slurry and other impurities are not cleaned up. After the formwork is removed, the concrete surface is bonded. (3) If the formwork is wet or not wet enough, it will absorb the concrete moisture on the surface of the component and cause excessive dehydration of the concrete surface.(3) The joints of the tracking board are not loose, causing local mud leakage.