A Study On The Freeze Injury Of Brick Construction In Heritage Buildings

After a long period of time, the durability of brick heritage buildings declines. And also, with their different geographical location and climatic conditions, brick buildings appreciate diseases occurred in different situations. Among them, the freeze injury of the brick construction in heritage buildings is one of the major diseases. Through the visits of heritage buildings in cold regions, to a research institution, the results of freeze injury census show that there occurred different degrees of freeze injury on nearly 95% of the brick heritage buildings. Freeze injury of brick construction in heritage buildings is widespread.The status of research is the basis for the study on freeze injury of brick construction in heritage buildings. Firstly, in this paper, natural properties of the brick heritage buildings in cold regions were discussed: From the natural environment of heritage buildings in cold regions, there are extreme cold climatic conditions and micro alkaline soil base; From the material point of view in the properties of heritage buildings, the brick and mortar of heritage buildings, as compared with modern material, whether from the production process, the mechanical properties or even the antifreeze performance has a certain gap, which directly affect the performance of the brick masonry. Natural attributes of brick heritage buildings in cold regions is an important factor affecting the occurrence of freeze injury.Through the field investigation, we found that the main manifestations of freeze injury on brick construction heritage buildings can be divided into the cracks in the wall, the crisp base in the wall and the wall mortar joint off these three kinds. Through the collation of statistical information on the investigation, we identified these three freeze injury forms on basic shape and distribution of the laws that: Cracks in the wall are mainly distributed on the wall upon each long edge of the window, the wall under a high window of the gable side and the wall under the eaves, the number of diagonal cracks is more than vertical cracks; Crisp base in the wall are mainly distributed on the foundation wall and the roof edge of the wall, the number of slightly wall crisp base is more than serious wall crisp base; The wall mortar off is often associated with wall crisp base simultaneously.The emergence and development of freeze injury of the brick construction in heritage buildings is a process of repeated freezing and developed. In this process, retention and repeated freezing and thawing of moisture in the masonry, is the main cause of the freeze injury of the brick construction in heritage buildings. In this paper, the causes of the retention of moisture and freeze-thaw cycles play an important role as the starting point to explore the reason and the weaknesses of the cracks in the wall, the crisp base in the wall and the wall mortar joint off.In short, the thesis use the freeze injury of the brick construction in heritage buildings for study, research from the status quo of freeze injury, the form of freeze injury and the freezing mechanism these three aspects to clarify the nature of freeze injury of the brick construction in heritage buildings, hoping to provide theoretical basis on how to avoid it and expect to contribute to the future on the subject of renovation and reuse of brick construction in heritage buildings.