Commonly used methods are X-ray techniques [20; 21], computational tomography (CT) [22; 23; 24], ultrasonic tomography [25; 26], etc. X-ray methods are an effective technique for accurately showing the level of cracking but have limitations associated with expensive equipment. In addition, long-term use of X-rays can cause serious side effects on the human body. CT scanning techniques have the advantages of non-destructive, dynamic, quantitative detection, high-resolution digital image display, etc. However, the method requires complex software for analysis. Although ultrasonic tomography can achieve general evaluation of concrete structure damage, and can not fully reveal the structural micro-crack extension state. In general, there are deficiencies in the whole process of monitoring concrete crack propagation. The most commonly used techniques to examine the process of concrete crack propagation are acoustic emission (AE) and digital image correlation (DIC) [27]. AE are the stress waves caused by the rapid release of energy within the concrete structure due to the elastic deformation and crack growth of the material itself when the concrete structure is subject to external force or internal force [28; 29]. AE are commonly related to concrete structural damage. Thus, AE can evaluate the whole process of the concrete structure cracking [30; 31]. However, it is sometimes difficult to establish a quantitative relationship with the crack propagation parameters of concrete structures. In addition, the evolution of strain is the macro-performance of concrete material in the process of fracture [32]. DIC recognizes the surface of the measuring concrete structure in digital camera images and allocates coordinates to the image pixels. The first image of the concrete structure represents the undeformed state. After or during the deformation of the concrete structure, extra images are recorded. Then, the computing system compares the digital images and calculates the displacement and deformation of the concrete structural characteristics [33; 34]. Therefore, DIC technology overcomes the disadvantage of traditional strain gauges, i.e., that they cannot accurately identify the position of crack initiation and the crack propagation path [35]. An effective experimental method for obtaining the process of concrete cracks propagation is by comparing AE and DIC. The strain parameters obtained by DIC can be quantitatively linked to the crack propagation stage. Therefore, it is necessary to study the law of frost-heave crack propagation by revealing the strain evolution at the crack tip and establishing the strain criterion of the frost-heave crack propagation. Based on DIC and AE technology, in this study, the process of frost-heave crack propagation in concrete specimens was studied respectively. An evolution law of generalized strain (\(\epsilon\)) and AE events location on the surface of the specimens during frost-heave crack propagation is revealed. The validity of applying surface strain to study frost-heave crack propagation is verified by comparing two experimental results. Then, based on linear elastic fracture mechanics and traditional strength theory, a double-strain criterion for frost-heave crack propagation is proposed. Furthermore, the proposed double-strain criterion is successfully applied to study the influence of different factors on the propagation state of cracks. The research results provide important theoretical and experimental support for crack maintenance and the prevention of frost-heave in slab-tracks in cold areas.