Analysis of internal and external factors causing cracks in mortar putty powder

At present, the cracks and cracks of mortar and putty are a universal problem. Shandong chuangyao biotechnology manufacturer has made a simple analysis on the internal and external causes of cracks in mortar and putty powder

1. The "internal causes" of mortar and putty cracks

The cracks of mortar putty are mainly caused by the large dry shrinkage and fast drying shrinkage of mortar and putty products and the destruction of mortar structure due to large internal stress. Generally speaking, cracks are irregular cracks, which are often called tortoise cracks. Tortoise cracks are mainly caused by the fact that some manufacturers do not fully understand the properties, functions and technical principles of raw materials, the raw materials used do not meet the requirements, and the formula is not scientific and reasonable, resulting in unstable product quality and poor crack resistance. After construction, large-scale cracks, hollowing and falling off problems appear soon after construction.

We all know that the strength and anti cracking effect of mortar have an important relationship with water. The hydration and setting hardening of cement is a progressive and continuous process. The hydration is first followed by setting. The result of setting and hardening depends on the hydration conditions. The more hydration is, the better the water curing is, and the longer the curing time is, the higher the strength will be, the smaller the shrinkage will be, and the better the anti cracking effect will be Good; the hydration and setting hardening speed of cement is also obviously affected by the ambient temperature, that is, if the ambient temperature is high, the hydration and hardening speed will be fast; if the ambient temperature is low, the hydration and setting hardening speed of cement will be slower correspondingly. The cement mortar with early drying, early hardening and early strength will shrink too fast and the shrinkage force is too strong due to poor water retention and poor self-care ability, and it is easy to produce large-area cracking.

Tortoise crack is mainly related to cement. No matter what type of cement it is, there is drying shrinkage problem. From the test results, the strength, stability and crack resistance of sulphoaluminate cement and white cement are not as good as ordinary portland cement. The main reason is that these products have large shrinkage, strong shrinkage force and fast drying shrinkage, which are easy to cause turtle cracks.

2. The "external causes" of mortar and putty cracks

The "external causes" of putty mortar cracks are mainly caused by foundation, construction technology and natural environment. Generally, the unscientific and unreasonable design and construction of buildings, foundation deviation and settlement, too thick plastering at one time during construction, obvious cracks in the base before construction, stress caused by large wind pressure, continuous high temperature and dry weather after construction, etc., will cause cracks. Cracks and cracks are generally manifested in cracks with horizontal and vertical shapes It is of irregular form.

There are basically no reliable materials and technical means to completely repair cracks and cracks. The result will cause great difficulties to building decoration, decoration, waterproof engineering and future maintenance work. This is because the size and shape of cracks in external walls vary with the environmental conditions (foundation settlement, earthquake, etc.) and temperature difference and humidity In other words, the gap size will change when the temperature is low in winter and high in summer, even in rainy days and sunny days in the same season. Cracks and cracks can be divided into different sizes. Large cracks and cracks can be easily seen. Small cracks may not be visible to the naked eye. However, as long as water is poured on the dry wall, the tiny cracks can be clearly seen. For more technical information about building materials industry, please pay attention to Shandong chuangyao biotechnology official website www.cyhuagong.com