Investigate And Control Measures Of The Cracks In The Lightweight Aggregate Concrete Blocks Filled Wall

The cracks in frame structure infilled wall with the lightweight aggregate concrete blocks have been become a very serious quantity problem in the realm of construction and restricted the application of lightweight aggregate concrete blocks which are new type building materials.According to the large numbers survey of the cracks actuality of lightweight aggregate concrete blocks in the city zone of Chongqing, it is very serious that the cracks in the infilled wall with the lightweight aggregate concrete blocks and every building is existing the crack problems.According to the large numbers survey of the production and application actuality of lightweight aggregate concrete blocks in Chongqing, this paper consideres the primary problems are the higher water absorption in blocks ,poor quality in masonry, inconsequence in fabric measures, poor workability in mortar , faultiness in criterion of check and accept.Based on the above problems, this paper investigated the performance of light aggregate concrete blocks and mortars of which influence the cracks in the laboratory, and proved the reliability of the controlling measures infilled wall with the 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 infilled wall with the lightweight aggregate concrete blocks,the main reasons are as follows:①The lightweight aggregate concrete blocks are poor quality, compression strength and large shrinkage;②The amount of shale particle in the block is very lower and the amount of fly ash in the block is very higher, result in the shrinkage of blocks is higher;③The shrinkage increased markedly when the water contain ratio of lightweight aggregate concrete blocks is very higher;④The temperature difference between indoor and outdoor and different seasons caused biggish temperature deformation of the infilled wall;⑤In the course of construction, in order to mason that the blocks is wetted with a lot of water, result in the shrinkage or expanding of blocks are not uniformity;⑥The difference in the shrinkage of blocks and mortar is bigger when the relative humidity is changing;⑦The detailing requirement is not reasonable and there is a lack of the measures to avoid the cracks in the infilled wall.⑧The construction quality is poor, the thickness of mortar joint is not achieved the prescript of criterion.⑨The 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 analysis of cracking reasons in the infilled wall, this paper bring forward some measures to avoid the cracks. The measures are as follows:①Using the good quality blocks, the time of conservation is not less than 28d;②At 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%;③Avoiding to masonry infilled wall in the high temperature of the season;④Enhances the workability and the consistency of mortar,controls the consistency of mortar is not less than 90 mm;⑤Improves the construction quality,controls the thickness and flatness of mortar joint to achieve the prescript of criterion;⑥Improves 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;⑦The mortar for coating and configuration column should carry through when the infilled wall was masonry thirty days;⑧Configuration column spacing and tense reinforcing steel bar achieve the prescript of criterion,and avoiding to excavate hole in the infilled wall.