## 1 Introduction  
Currently, concrete is extensively used in civil engineering projects [1]. Against the backdrop of China's active promotion of the western development strategy, many construction projects are facing severe challenges in terms of working environments. These projects have imposed stricter standards and requirements on the mechanical and durability properties of concrete, leading to the development of high-strength concrete with superior mechanical and durability properties. The enhancement of concrete is typically achieved by reducing the water-binder ratio [2]. To maintain the workability of high-strength concrete, it is necessary to add high-efficiency water-reducing agents to keep its good fluidity and meet the pumping requirements on construction sites [3]. However, with the widespread application of high-strength concrete in the construction field, we also need to be aware of the adverse issues it may cause. High-strength concrete has a low content of free water available for hydration reactions, and the rapid decrease in free water content during cement hydration due to the large amount of cement used can lead to increased capillary stress, thus exacerbating material shrinkage issues caused by humidity gradients [4; 5]. If high-strength concrete is not adequately moisturized during the early curing stage and hydration is incomplete, it can lead to autogenous shrinkage and drying shrinkage, resulting in cracks in the concrete structure at an early stage. These cracks not only provide a pathway for the intrusion of harmful substances from the outside but also weaken the load-bearing capacity of the concrete structure [6], leading to durability issues and failure to achieve the desired good durability of high-strength concrete [7; 8]. This not only shortens the service life of the concrete structure but also significantly affects its early-stage strength development due to insufficient internal moisture, which slows down the hydration reaction rate of cement paste [9]. Additionally, repairing concrete cracks is not only labor-intensive and costly but also economically inefficient [10]. Therefore, compared to ordinary concrete, high-strength concrete has a higher demand for early-stage curing. To effectively mitigate its early-stage autogenous and drying shrinkage issues, it is necessary to select appropriate curing methods for high-strength concrete to ensure its durability. Concrete curing can be divided into two basic types: external curing and internal curing. Ordinary concrete is typically cured through external methods such as water storage, watering, spraying, or covering with wet sacks [11]. However, these methods have long curing cycles, require significant manpower and resources, and may vary in effectiveness depending on the individual performing the curing. For cement-based materials with a low water-binder ratio, their dense structure and the difficulty of external curing water penetrating into the interior of the concrete make it challenging to provide timely moisture to promote the hydration reaction of the paste. Therefore, this curing method is not effective in mitigating the autogenous drying caused by internal water scarcity in concrete [12], thus limiting its ability to reduce paste shrinkage and ensure good durability. As a result, there is a need for an alternative and more effective curing technique that can pre-store curing moisture inside high-strength concrete, replenish moisture when needed, and participate in the entire hydration process of the concrete until the relative humidity difference between the interior and exterior of the paste reaches zero. This internal curing approach can effectively mitigate autogenous and drying shrinkage. Common internal curing methods include internal curing with saturated lightweight aggregate (LWA) [13; 14] and super absorbent polymer (SAP) [15; 16; 17; 18; 19; 20; 21]. These materials used as internal curing carriers can continuously release water loaded inside the concrete, maintaining a relatively stable internal humidity environment.