Dry mix mortar cracking problem

1. What is plastic cracking of dry-mixed mortar?

Plastic cracking refers to the cracking of the mortar before or during the hardening process. It generally occurs in the early stages of mortar hardening, and plastic cracking cracks are generally thicker and shorter in length.
Reason analysis: Shortly after plastering, the mortar will produce shrinkage stress due to rapid moisture reduction in the plastic state. When the shrinkage stress is greater than the bonding strength of the mortar itself, cracks will occur on the surface.
1.1 It is often related to the material properties of the mortar and the ambient temperature, temperature and wind.
1.2 The larger the cement content, the smaller the sand fineness modulus. The higher the mud content, the greater the water consumption. Mortar is more prone to plastic cracking.

2. What is shrinkage and cracking of dry-mixed mortar?

Shrinkage cracking refers to cracking of mortar after hardening. It generally occurs in the late stage of mortar hardening, dry shrinkage and cracking, and the cracks are characterized by being thin and long. As shown in the picture: Cause analysis: Dry shrinkage cracking is a crack caused by water loss and volume shrinkage after the mortar hardens. It usually takes a year or even 2 to 3 years to gradually develop.
2.1 The mortar uses a large amount of cement and its strength is too high, resulting in volume shrinkage.
2.2 The post-maintenance of mortar is not in place.
2.3 The drying shrinkage value of mortar admixtures or admixtures is large.
2.4 The wall itself is cracked and the interface is not handled properly.
2.5 The mortar labels are used indiscriminately or incorrectly, and the elastic modulus of the base material and the mortar are too different.
Preventive measures: Reduce the amount of cement and add appropriate admixtures to reduce the drying value. Strengthen publicity and guidance to the construction party, strengthen management, and strictly require construction according to the ready-mixed dry-mix mortar construction method.
The above is about “Dry mix mortar cracking problem”