What is the correct way to observe and measure cracks?

1, and the cracks to be observed shall be numbered uniformly. At least two groups of observation marks shall be set for each crack, one at the widest part of the crack and the other at the end of the crack. Each group of marks consists of one mark on both sides of the crack.

2. For the observation of the position, direction and length of cracks on concrete buildings, mark the two ends of cracks with paint, or draw grid coordinates on the concrete surface, measure with a steel ruler, or regularly measure the coordinate difference with a grid plate. For important cracks, punctuation marks can also be buried in their representative positions, that is, metal bar mark points are buried on both sides of the cracks, and the change of the distance between the two points can be measured regularly with vernier calipers, so that the change of the crack width can be accurately obtained. Close-range photogrammetry should be adopted for many cracks with large area and inconvenient manual measurement.

3. When it is necessary to continuously monitor the change of cracks, the automatic recording method of crack meter or sensor can also be adopted. The observation period of cracks should depend on the change speed of cracks. Usually it can be tested once every two months at first, and then once every month or so. When cracks are found to increase, the observation times should be increased until continuous observation is made for several days or once a day.