There are many factors causing the cracking of GRC lightweight members, but the main reason is the shrinkage deformation of members. In the process of shrinkage, the component will produce shrinkage stress, resulting in tensile deformation of the component and joint material. When the tensile deformation is not enough to offset the shrinkage deformation, cracks will occur.

開裂的程度隨地區不同有很大差異。南方尤其是沿海地區氣候潮濕，全年絕大多數時間空氣相對濕度在90%左右，在這潮濕的氣候環境下，GRC輕質構件的含水率始終不下，如果不采取特別的烘干措施，構件在自然狀態下的含水率無法小于《標準》規定的10%。因此，南方尤其是沿海地區更容易開裂。開裂通常發生在構件與構件以及構件與梁的接縫處。開裂的寬度與構件的干縮值、冷縮值以及構件的橫向長度等有關，絕大多數裂縫寬度在0.5mm以內。

The degree of cracking varies greatly with different regions. The climate in the south, especially in coastal areas, is humid, and the air relative humidity is about 90% most of the year. In this humid climate environment, the moisture content of GRC lightweight components is always not lower. If special drying measures are not taken, the moisture content of components in natural state cannot be less than 10% specified in the standard. Therefore, the south, especially the coastal areas, are more prone to cracking. Cracking usually occurs at the joints between members and between members and beams. The crack width is related to the dry shrinkage value, cold shrinkage value and transverse length of the member. Most crack widths are within 0.5mm.

目前開裂問題的途徑主要是：從改善構件的材性和在安裝、構造。

At present, the main way to solve the cracking problem is to improve the material properties of components and in installation and structure.

改善構件的材性主要應達到兩個目標：一是降低構件的收縮值，其中包含干縮值和冷縮值，以減少構件的收縮變形；二是提構件和接縫材料的彈性，增加拉伸變形值。通過這“一增一減”來盡量達到構件的收縮變形與拉伸變形的平衡。但目前GRC輕質構件的特性使拉伸值與收縮值平衡比較有困難。

To improve the material properties of components, two objectives should be achieved: one is to reduce the shrinkage value of components, including dry shrinkage value and cold shrinkage value, so as to reduce the shrinkage deformation of components; The second is to improve the elasticity of components and joint materials and increase the tensile deformation value. Through this "one increase and one decrease" to try to achieve the balance between shrinkage deformation and tensile deformation. However, the characteristics of GRC lightweight components make it difficult to balance the tensile value and shrinkage value.

在構件的安裝構造上：目前的主攻方向普遍是放在構件接縫處理和按縫材料上。在構件本身的質量合格的前提下，構件的接縫處始終是薄弱環節，裂縫容易在這里產生。單純用“粘牢”的辦法來防止裂縫產生較困難，即使在構件的接縫處貼上玻纖布增強也很難。構件一定會收縮，靠硬拉難以拉住，結果往往構件開裂或是構件縫開裂，因為并沒有收縮變形與拉伸變形的平衡問題。更何況構件安裝時需上下、前后反復錯動才能對齊，難以做到砂漿飽滿，多數是安裝后再補塞砂漿，故不容易保證粘牢。

On the installation structure of components: at present, the main attack direction is generally on the component joint treatment and joint materials. On the premise that the quality of the component itself is qualified, the joint of the component is always a weak link, and cracks are most likely to occur here. It is difficult to prevent cracks simply by "sticking", and it is difficult to solve even if glass fiber cloth is pasted at the joints of components. The component will shrink, and it is difficult to pull it by hard pulling. As a result, the component often cracks or component joints crack, because the balance between shrinkage deformation and tensile deformation is not solved. Moreover, the components need to be staggered up and down, back and forth repeatedly during installation, so it is difficult to make the mortar full. Most of them are filled with mortar after installation, so it is not easy to ensure the adhesion.

采用彈性砂漿增加拉伸變形值的方法，單就防止構件縫開裂而言，思路和方法都是正確的。但實踐起來卻有一個矛盾難以，即彈性砂漿的彈性與構件飾面材料的低彈性之間的矛盾。構件飾面材料(如膩子)的拉伸率卻遠沒有彈性砂漿這么大，構件表面仍然會開裂。若為此而要求飾面材料也達到同樣的拉促率，成本上不現實

The method of increasing tensile deformation value with elastic mortar is correct only in terms of preventing member joint cracking. But in practice, there is a contradiction that is difficult to solve, that is, the contradiction between the elasticity of elastic mortar and the low elasticity of component facing materials. The tensile rate of component facing materials (such as putty) is far less than that of elastic mortar, and the component surface will still crack. If the finishing materials are required to reach the same pulling rate for this purpose, the cost is unrealistic