Effect of redispersible emulsion powder on the performance of thick layer gypsum-based self-leveling mortar


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2020-02-28

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Redispersible emulsion powder is an important additive that affects the performance of thick-layer gypsum-based self-leveling mortar. The effect of redispersible emulsion powder on the physical and mechanical properties of thick-layer gypsum-based self-leveling mortar was tested, and the principle of redispersible emulsion powder to improve the mechanical properties of gypsum-based self-leveling mortar was revealed through microscopic analysis.

Redispersible emulsion powder is an important additive that affects the performance of thick-layer gypsum-based self-leveling mortar. The effect of redispersible emulsion powder on the physical and mechanical properties of thick-layer gypsum-based self-leveling mortar was tested, and the principle of redispersible emulsion powder to improve the mechanical properties of gypsum-based self-leveling mortar was revealed through microscopic analysis.

Redispersible emulsion powder is a widely used organic binder, which can be used in gypsum-based building materials to improve the performance of products. It was found that the initial fluidity of thick-layer gypsum-based self-leveling mortar first increased and then decreased with the increase of rubber powder dosage because the dissolved water of rubber powder has a certain viscosity. When the dosage is low, the increase of slurry viscosity improves the suspension ability of slurry to filler, which is conducive to the flow of slurry. When the dosage of rubber powder continues to increase, the increase of slurry viscosity leads to the increase of slurry viscosity and the decrease of fluidity. The amount of rubber powder has almost no effect on the fluidity of mortar in 20min.

Rubber powder as an organic binder, the development of strength depends on the evaporation of slurry moisture, film formation bond strength, thick layer gypsum self-leveling mortar pouring 24h still has a high moisture content, the strength of rubber powder has not been developed, the performance of gypsum-based self-leveling mortar 24h strength with the increase of rubber powder content showed a decreasing trend. When the content of rubber powder is 2.0%, the 24h flexural strength and compressive strength of mortar are decreased by 25.5 and 11.9 respectively compared with those without rubber powder. Under the absolute dry state, the water in the gypsum-based self-leveling mortar evaporates, and the rubber powder can form a continuous film with good bonding force. The absolute dry strength of the gypsum-based self-leveling mortar increases with the increase of the rubber powder content. When the rubber powder content is 2.0, the absolute dry flexural strength and compressive strength of the mortar increase by 63.5 36.8 respectively compared with that without rubber powder.

There are a large number of rod-like and columnar dihydrate gypsum crystals and irregular filler dihydrate gypsum crystals and between dihydrate gypsum crystals and filler in the gypsum-based self-leveling mortar without adding rubber powder. The strength of the gypsum-based self-leveling mortar is generated by irregular and close packing. In the gypsum-based self-leveling mortar with 2.0 redispersible latex powder, the rubber powder forms filamentary connection in the gypsum-based self-leveling mortar, and the dihydrate gypsum crystal and filler, an organic bridge is formed between crystals, and an organic film is formed on the dihydrate gypsum crystal, which wraps and connects the overlapping parts between the dihydrate gypsum crystals, thus increasing the cohesion and bonding force of the gypsum-based self-leveling mortar, and improving the strength of the gypsum-based self-leveling mortar. The rubber powder has film-forming property in the mortar, which can improve the cohesion and bonding strength of the dry mortar, the film-forming substance between the dihydrate gypsum crystal and the filler forms an effective bond between the dihydrate gypsum crystal and the filler, which improves the cohesion between the dihydrate gypsum crystal and the filler, thus improving the bonding strength of the gypsum-based self-leveling mortar on the macro. When the content of rubber powder is 2.0%, the bond strength of mortar is 46.5% higher than that without rubber powder.

Thick layer of self-leveling cement through re-dispersible emulsion powder to adjust the performance of desulfurization gypsum or phosphogypsum, adding industrial waste as aggregate, make full use of industrial waste residue, both to achieve economic benefits, but also have good social benefits.







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