If the cement stabilized macadam base can't lift the core, it is judged as unqualified. 1, the core sample can only be taken after the curing period, otherwise the cement will not reach the strength and the crushed stone will not bond. It usually takes 7 days to core. If the coring is unsuccessful, it means that the paving water is not in place when it is stable, or the base is unqualified. 2. After paving is stable, it shall be maintained in time. Don't let vehicles walk on it, or the lower part will be good after coring, but the surface will be hairy or loose, which will affect the acceptance. 3. When sampling, the core should be drilled at an appropriate position. If it is not drilled to the bottom of the cement stabilized base, the core sample will not be lifted. 4. After drilling to the end, the core sample can't be lifted, and it can't form a whole, indicating that the cement consumption is small, which can be directly judged as unqualified. 5. The coring of water-stabilized macadam layer mainly detects the thickness, compressive strength, integrity and compactness of the core sample, and can also identify the gradation of macadam through the core sample. After field sampling, cut it into specimens with the height-diameter ratio of 1: 1, smooth the cross section with quick-setting mortar or sulfur mortar, and then test it according to the unconfined compressive strength test method. In order to prevent coring from affecting strength, only a drill bit with a diameter of 150mm can be used.