## 1 Introduction  
It is now understood that once cement concrete pavement has been poured and completed, environmental factors can cause temperature and humidity gradients inside the concrete, resulting in slab surface shrinking, expansion, and warping, which cause large tensile stresses. Ultimately, these stresses can trigger cracking and even spalling [1]. Especially under the coupling effect of high temperature, high humidity, heavy rain, and strong wind, media such as water and erosion ions in the environment accelerate to penetrate into the interior of concrete along microcracks, causing further crack growth, increasing the probability of diseases such as concrete pavement peeling, affecting service life performance, and further reducing service life.  
In recent years, much emphasis has been placed on temperature differences and their impact on cement concrete pavement panels domestically and abroad [2; 3; 4; 5; 6; 7], Scholars have also conducted numerous studies on mechanics [8; 9]. China's pavement panel design specification now incorporates the influence of temperature variation on pavement panel design calculations.  
Unlike the effect of the temperature field, the effect of the moisture field has been largely understudied and is not considered in current concrete pavement design and calculations [10]. Recent research has highlighted the significant impact of humidity on the deformation and stress of pavement panels, especially during the early stages of development [11; 12]. [PERSON] et al. found that the humidity gradient along the board body can cause the board to warp [13]. Based on the coefficient of thermal expansion, [PERSON] et al. could linearly equivalent the humidity gradient to a temperature gradient and calculated the humidity stress through the equivalent temperature gradient [14; 15]. [PERSON] et al. considered the influence of bending creep on humidity stress [16; 17], and [PERSON] and [PERSON] analyzed the influence of temperature and humidity on the structural modulus of concrete pavement [18; 19; 20]. [PERSON] et al. [21] conducted experiments to measure the curvature of concrete panels due to humidity strain after 1 to 2 years. [PERSON], [PERSON] et al. [22] carried out numerical simulations and found that the humidity warpage of pavement panels under extremely dry conditions was significant, with a magnitude of up to 2.52 mm and a corresponding equivalent temperature difference of \(-107\ ^{\circ}\)C/m, which is comparable to the daily temperature difference. In addition, a significant moisture difference could cause a large moisture shear stress in the surface layer of concrete pavement panels, leading to delamination and early edge spalling of the panels [23].  
At present, research on the moisture field is still primarily focused on a two-dimensional perspective [24], which limits the ability to consider the influence of the diffusion effect on the moisture field in multiple dimensions. Additionally, there is a lack of research on the moisture field in special climatic regions. To address the above problems, this article studies the early age humidity field behavior and the effect of cement concrete pavement panels from the perspective of a three-dimensional humidity field, combined with a humid and hot climate environment, in order to provide theoretical support for further improving pavement performance.