What is the waterproof effect of paraffin emulsion for gypsum?

Influence of emulsification conditions on paraffin emulsion

The preparation of paraffin emulsion requires higher emulsification conditions. The main factors affecting the stability of paraffin emulsion include stirring speed, emulsification time and emulsification temperature. Three influencing factors of the trial:

(1) The stirring speed is l200r/min～1400r/min. If the stirring speed is slow, the paraffin wax is difficult to disperse uniformly in the water phase, the obtained paraffin wax emulsion is unstable, and the phenomenon of demulsification and stratification will occur; if the stirring speed is too fast, foam will be generated and energy loss will be caused.

(2) The emulsification time is 40min. If the emulsification time is short, the emulsifier is not completely dispersed, the formed emulsion is unstable, and the emulsion will be layered quickly; if the emulsification time is long, the emulsion will solidify into a paste and lose its fluidity after being placed. Results of large particles.

(3) The emulsification temperature is 85℃～90℃. When the emulsification temperature is lower than 85°C, the obtained paraffin wax emulsion is unstable and easy to delaminate.

 Features of paraffin emulsion waterproofing agent

Hemihydrate gypsum is hydrated to form dihydrate gypsum, and the crystals cross and overlap each other to form a spatial network structure, which is the source of strength for gypsum materials. The solubility of dihydrate gypsum is relatively large, and the contact points of crystals are reduced due to contact with water, showing poor water resistance. Under the action of surfactant, paraffin emulsion particles are arranged in a directional arrangement on the surface of gypsum particles, the hydrophilic groups are connected with the surface of gypsum particles, and the hydrophobic groups are uniformly facing outwards, forming a dense protective layer after water loss.

Paraffin wax emulsion is used as a waterproofing agent for gypsum products. It has the characteristics of less dosage, easy operation, simple process, and high production efficiency, which is equivalent to the production efficiency of ordinary gypsum products. However, waterproof gypsum products modified with inorganic materials such as cement, slag, fly ash, and lime have high apparent density, generally between 1300kg/m3 and 1400 kg/m3. Lightweight materials need to be added to reduce the apparent density of the product. . Secondly, the amount of inorganic waterproof material is large (generally about 30%), and the curing time and production cycle of the product are long.

When adding inorganic modified materials, paraffin wax emulsion and glass fiber to the desulfurized building gypsum, the water resistance of the product is significantly improved and the mechanical strength is sufficient; the optimal ratio of water-resistant gypsum products is: modified building gypsum 94% (containing 8% of inorganic modified materials), 5% of paraffin emulsion, 1% of glass fiber, and the softening coefficient of gypsum products reaches 0.65.