Investigate Of The Cracks In The Infilled Wall Made Of The Concrete Blocks For Frame Structure In Chongqing

The cracks in the frame structure infilled wall with the lightweight concrete blocks has become a very serious quantity problem in the realm of construction and restricted the application of lightweight concrete blocks which are new type building materials.According to the large numbers survey of the cracks actuality in Chongqing, this paper investigated the basic performance of light aggregate concrete blocks, autoclaved aerated concrete blocks and mortars which influence the cracks in the laboratory and monitored the deformation of the frame structure infilled wall with the autoclaved aerated concrete blocks and shale particle concrete hollow blocks in the construction local.At the basic of systemic investigate, this paper analyses the primary reasons of cracks in the frame structure infilled wall with the lightweight concrete blocks,the main reasons are as follows:(1) The lightweight concrete blocks are poor quality and large shrinkage.(2) The autoclaved aerated concrete has the poor quality of durability,the carbonation and water contain circulation reduced the compression strength and rupture strength.(3) The shrinkage increased markedly when the water contain ratio of lightweight concrete blocks is very higher.(4) The temperature difference between indoor and outdoor and different seasons caused biggish temperature deformation of the infilled wall(5) The absorption rate of autoclaved aerated concrete blocks is higher but the evaporation rate is smaller, when the water contain and relative humidity are changing,the deformation difference is appearing in the surface layer and interior of blocks. (6) The detailing requirement is not reasonable and there is a lack of the measures to avoid the cracks in the frame structure infilled wall.(7) The construction quality is poor, the thickness of mortar joint is not achieved the prescript of criterion. (8) The water preserving capability and workability of mortar are poor, so the shrinkage difference between mortar and blocks is bigger and the felt strength between mortar and blocks is lower. According to the large numbers survey of the cracks. According to the analysis of cracking reasons in the infilled wall, this paper bring forward some measures to avoid the cracks. The measures are as follows:(1) At the time to masonry infilled wall,according to the temperature and relative humidity of environment to control the water contain of lightweight aggregate concrete blocks is less than 6%～8% and control the water contain of autoclaved aerated concrete blocks is more lower.(2) Avoiding to masonry infilled wall in the high temperature of the season.(3) Enhances the workability and the consistency of mortar,controls the consistency of mortar is not less than 9.0 cm. Improves the construction quality,controls the thickness and flatness of mortar joint to achieve the prescript of criterion.(4) Improves the construction quality of the bricking upper infilled wall,the bricking upper infilled wall should carry through when the infilled wall has masonry thirty days. (5) The mortar for coating and configuration column should carry through when the infilled wall was masonry sixty days.(6) Configuration column spacing and tense reinforcing steel bar achieve the prescript of criterion,and avoiding to excavate hole in the infilled wall.