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(qū)不同有很大差異。南方尤其是沿海地區(qū)氣候潮濕，全年絕大多數(shù)時(shí)間空氣相對(duì)濕度在90%左右，在這潮濕的氣候環(huán)境下，GRC輕質(zhì)構(gòu)件的含水率始終不下，如果不采取特別的烘干措施，構(gòu)件在自然狀態(tài)下的含水率無法小于《標(biāo)準(zhǔn)》規(guī)定的10%。因此，南方尤其是沿海地區(qū)更容易開裂。開裂通常發(fā)生在構(gòu)件與構(gòu)件以及構(gòu)件與梁的接縫處。開裂的寬度與構(gòu)件的干縮值、冷縮值以及構(gòu)件的橫向長(zhǎng)度等有關(guān)，絕大多數(shù)裂縫寬度在0.5mm以內(nèi)。

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(gòu)件的材性和在安裝、構(gòu)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(gòu)件的材性主要應(yīng)達(dá)到兩個(gè)目標(biāo)：一是降低構(gòu)件的收縮值，其中包含干縮值和冷縮值，以減少構(gòu)件的收縮變形；二是提構(gòu)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(dá)到構(gòu)件的收縮變形與拉伸變形的平衡。但目前GRC輕質(zhì)構(gòu)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(gòu)件的安裝構(gòu)造上：目前的主攻方向普遍是放在構(gòu)件接縫處理和按縫材料上。在構(gòu)件本身的質(zhì)量合格的前提下，構(gòu)件的接縫處始終是薄弱環(huán)節(jié)，裂縫容易在這里產(chǎn)生。單純用“粘牢”的辦法來防止裂縫產(chǎn)生較困難，即使在構(gòu)件的接縫處貼上玻纖布增強(qiáng)也很難。構(gòu)件一定會(huì)收縮，靠硬拉難以拉住，結(jié)果往往構(gòu)件開裂或是構(gòu)件縫開裂，因?yàn)椴]有收縮變形與拉伸變形的平衡問題。更何況構(gòu)件安裝時(shí)需上下、前后反復(fù)錯(cuò)動(dòng)才能對(duì)齊，難以做到砂漿飽滿，多數(shù)是安裝后再補(bǔ)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(gòu)件縫開裂而言，思路和方法都是正確的。但實(shí)踐起來卻有一個(gè)矛盾難以，即彈性砂漿的彈性與構(gòu)件飾面材料的低彈性之間的矛盾。構(gòu)件飾面材料(如膩?zhàn)?的拉伸率卻遠(yuǎn)沒有彈性砂漿這么大，構(gòu)件表面仍然會(huì)開裂。若為此而要求飾面材料也達(dá)到同樣的拉促率，成本上不現(xiàn)實(shí)

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