How to improve the crack resistance of waterproof mortar


Release time:

2020-06-08

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polymer cement mortar
 
 
Polymer mortar is a kind of organic polymer material to replace part of the cement, and cement together as a cementitious material of a mortar. Commonly used polymers are polyvinyl acetate, ethylene copolymer emulsion, acrylate copolymer emulsion, styrene-butadiene rubber emulsion and other polymers. Mixing a certain proportion of polymer can overcome the common problems of large shrinkage, brittleness and low bond strength of ordinary mortar, and can effectively improve the plastic deformation ability and bond strength of mortar, and the anti-cracking effect is obviously improved. But polymer mortar should pay attention to the following issues:
 
 
① In cement mortar, cement hydration requires a humid environment, while the polymer needs a dry environment to lose water and coagulate into a film. Therefore, the maintenance of polymer mortar must not only fully hydrate the cement but also ensure the polymer film formation, that is to say, it should be wet in the early stage and moderately dry in the later stage.
 
 
The higher the polymer content, the higher the compressive strength of the mortar, but the strength of the mortar with different polymers is different. Taking polyvinyl acetate as an example, Qian Xiaoqian's research shows that when the dosage is 10-15% of cement and the water cement ratio is about 0.4, the compressive strength of polymer cement mortar is about 30-40% lower than that of mortar without polymer, but the tensile strength and bonding strength are improved, and the deformation modulus is reduced by more than 30%.
 
 
Silicone waterproof mortar
 
 
The main component of organic silicon is methyl sodium silicate, which contains a polar factor-OH, which is easy to generate hydrogen bonds. The branched and reticular molecules of methyl silicone resin generated by further polycondensation reaction are hydrated with cement. It fills the pores and pores of mortar and increases the density and impermeability of mortar. Because these methyl silicone polymer has high plastic strength, it can reduce the shrinkage crack of mortar, reduce the shrinkage stress, and improve the crack resistance of mortar. In addition, because it disperses stress, it can prevent stress concentration and improve the interface effect and plasticity of mortar. Comprehensive improvement of the tensile properties of mortar. Before the construction of the grass-roots surface brush silicone water (1:8) solution once after the start of painting.
 

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