Study On The Control Measures Of Temperature And Shrinkage Cracks For Ceramsite Concrete-block Building

Concrete block, with a number of advantages such as soil-and-energy-saving, lightweight, high strength, fast construction and increasing net area, and so on, is the most suitable substitute of clay brick and will have broad development potential. However, further development of Concrete block buildings is restricted by the problems of temperature and shrinkage cracks in Concrete block buildings. Therefore, it has important practical meanings to study the temperature and shrinkage cracks problems in Concrete small block buildings and find effective measures to control temperature cracks in the walls.There axe several reasons leading to the cracks in Concrete block buildings, but most of the cracks in Concrete block buildings are non-loading cracks(deformation cracks) with temperature and shrinkage being the most important reasons. The locations and shapes of different types of cracks in the Concrete block buildings are summarized in this paper. Controlling measures to alleviate the cracks are also summarized based on various cracks, and the repairing methods of the cracks in Concrete block buildings are also introduced briefly.The mechanism of temperature and shrinkage cracks in Concrete block wall is analyzed, and the approximate calculation method of temperature stress in Concrete block wall and the practical calculation method of shrinkage deformation are summarized.Nonlinear analysis on the block-wall subjected to horizontal load and temperature difference is performed using concrete material model by finite element software ANSYS. The characteristics of the distribution and development of the cracks and deformations are also studied. The comparison between the theory analysis and test result indicates that the analysis model of block-wall crack being put forward in this paper is reasonable in certain degree.One of measures provided by the building code to alleviate cracks in Concrete block wall is to install sliding-layer in longitudinal wall. The effects of the sliding-layer installed in longitudinal wall under the influence of temperature are analyzed by the finite element program. The finite dement analysis indicates that the cracking temperature difference has little changes, the locations of the initial cracks move towards the center, the sections near the sliding-layer don't crack in general, and the lateral displacement of wall reduces in certain degree, after the partial sliding-layer is installed between the longitudinal wall and roof panel in Concrete block building. From the result of analysis, this measure has no obvious effect to prevent cracks, and reducing wall length and expansion joint spacing has no effective impact to alleviate wall cracking.The necessity and significance of energy-saving of the building is introduced. The ways meeting energy-saving standard of Concrete block wall are summarized. The paper tries to combine crack resistance with energy-saving of the building and bearing, and studies a kind of new type ceramsite concrete block suitable for regions where summer is hot and winter is cold. All kinds of requirements which should be satisfied by the new type block are analyzed. The design of Concrete block is also performed based on these requirements.