## 1 Introduction  
The durability of concrete has received much attention in the field of construction materials due to the need for extended service life [1, 2]. However, cracks are considered to be one of the most important factors affecting the durability of cement-based materials during service, and their appearance is inevitable [3, 4]. The extension of cracks can lead to deterioration of cement-based materials, thus reducing their service life [5]. However, the \"after-the-fact\" nature of conventional maintenance suggests that cracks can only be repaired after they have occurred, which not only increases costs but also requires advanced techniques to accurately detect and locate internal cracks [6]. To meet this requirement, self-healing cement-based materials aimed at automatic crack repair and service life extension have attracted the interest of many researchers [7, 8]. The current self-healing technologies of cement-based materials mainly include: mineral self-healing technology [9], microbial self-healing technology [10] and microencapsulated self-healing technology [11]. The main mechanism of mineral self-healing technology is to mix mineral admixture into cement-based materials, and when there is water infiltration into cracks, the mineral admixture with special composition reacts with the calcium hydrooxide generated by hydration inside the cement-based materials in a pozzolanic reaction or swelling to produce CaSiO\({}_{3}\) gel and other crystals, thus achieving the purpose of healing the crack [12]. However, mineral admixtures have limited effectiveness in healing cracks in cement-based materials with widths exceeding 0.15 mm [13]. Microbial self-healing technology refers to the addition of microorganisms to cement-based materials to promote the production of some water-insoluble organic or inorganic compounds (e.g., CaCO\({}_{3}\)) through the metabolism or respiration of microorganisms for the purpose of healing cracks and filling pores [14]. However, microbial self-healing technology still has some problems to be solved, e.g., the pores of cement-based materials will decrease with age, the activity of extruded bacterial spores will decrease, and the self-healing ability will be reduced. The improper selection of microbial nutrient solution can reduce the mechanical properties and durability of cement-based materials [15]. Microencapsulated self-healing technology involves the direct incorporation of microcapsules (<1000 \(\upmu\)m in diameter) containing healing agents (core materials) into the cement-based materials [16]. When triggered by cracks or changes in the surrounding environment, the outer shell of the microcapsule ruptures, and the healing agent is released to heal cracks or defects in the cement-based materials [17]. Compared with the above self-healing technologies, microencapsulated self-healing technology has good application prospects due to its advantages, such as environmental adaptability and fast healing rate [18]. From the proposal of microencapsulated self-healing technology to the present, many researchers have conducted numerous studies. [PERSON] [19] prepared microcapsules with tung oil, Ca(OH)\({}_{2}\) and epoxy resin as core materials and gelatin as the shell and studied the presence of microcapsules in a strong alkaline environment to evaluate the self-healing ability of microcapsules. The results showed that the microcapsules containing tung oil had a good healing effect on the mortar specimens. [PERSON] [20] investigated the effect of microcapsules with diglycidyl ether of bisphenol A epoxy resin as healing agent and polystyrene-divinylbenzene (St-DVB) as shell material on the self-healing performance of cement-based materials. [PERSON] indicated that the best recovery of mechanical properties of specimens (60% pre-load damage) under standard curing was achieved when microcapsules were mixed at 2% of the cement mass.