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宝盈娱乐官网有裂縫的原因

發布時間:2019-04-03    編輯:上海bbin平台新型建材有限公司    瀏覽次數:50次

 1. 干縮變形產生裂縫

 
  加氣混凝土砌塊是高分散毛細孔結構,且大部分空洞呈封閉狀態,隨著時間的變化孔內的水分就不斷減少,在表面張力的作用下,毛細孔內就形成收縮應力,當這種應力達到一定程度砌體就會產生干縮。干縮變形特征是早期發展快,以后逐漸變慢并在相當長的時期內延續,使整個砌體處于徐變狀態。干縮裂縫分布廣、數量多、裂縫強度較嚴重,干縮變形是產生裂縫的主要原因。
 
 2. 砂漿對裂縫的影響
 
  普通砂漿的導熱系數約為0.9W/(m·K),線膨脹系數約為4×10-4mm(/m·℃),與加氣混凝土砌塊相差達到10倍左右,一旦環境溫度變化一定程度,則在砌筑砂漿、抹灰砂漿與砌塊之間產生溫度應力,當該應力大于粘結強度時裂縫就產生,該裂縫主要表現在頂層梁底與墻體之間,門、窗框與墻體之間,裂縫呈水平裂縫與斜拉縫砌塊。
 
 3. 施工不足產生裂縫
 
①未控制好砌塊的含水率,加氣混凝土砌塊出釜時含水率大多在35~40%,砌塊出釜(10~30d)后含水率在堆放正常的情況下可降至30%,此時方可上墻施工。
 
②砌筑時不按相關規范要求進行施工,砌塊表層的含水率、砌塊搭接長度、一次性砌筑高度不合理等造成裂縫。
 
③砌筑時未嚴格控制灰縫的飽滿度。
 
④未合理設置拉結筋,或未按規范在跨度或高度較大的墻體內設置構造柱、圈梁。
 
⑤抹灰前不進行除塵、濕潤墻面等措施。
 
⑥未在不同材料交界處進行加強措施處理。
 
 
1. Dry shrinkage creates cracks

The aerated concrete block is a highly dispersed capillary structure, and most of the holes are closed. With the change of time, the water in the hole continues to decrease. Under the effect of surface tension, the capillary hole forms a contraction stress. When this stress reaches a certain level, the masonry will produce dry shrinkage. Dry deformation is characterized by rapid early development, gradually slowing down and continuing over a long period of time, leaving the entire masonry in a state of creep. Dry shrinkage cracks are widely distributed, numerous, and the fracture strength is serious. Dry shrinkage deformation is the main reason for cracks.

2. Impact of mortar on cracks

The thermal conductivity of ordinary mortar is about 0.9 W /(M · K), the line expansion coefficient is about 4 × 10-4mm(/ M · °C), and the difference with the aerated concrete block is about 10 times, once the ambient temperature changes. To a certain extent, The temperature stress is generated between the masonry mortar, the mortar mortar and the block. When the stress is greater than the bond strength, the crack is generated. The crack is mainly represented between the top beam bottom and the wall, between the door and the window frame and the wall. The cracks are horizontal cracks and sloping seams.

3. Insufficient construction resulting in cracks

1 The water content of the block is not controlled properly. The water content of the gas-filled concrete block is mostly 35 to 40 % when it is filled. The water content of the block(10 to 30D) can be reduced to 30 % when the pile is normal. At this time, construction can be done on the wall.

2 When masonry does not carry out construction according to the relevant specifications, cracks are caused by the water content of the surface layer of the block, the length of the block, and the unreasonable height of the one-time masonry.

3 The fullness of the gray seam was not strictly controlled when masonry was made.

4 There is no reasonable setting of tendons, or structural columns and girders are not installed in the walls with large spans or Heights according to specifications.

5 Do not carry out dust removal, wet wall and other measures.

Enhanced measures were not taken at the junction of different materials.
 



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