Effect of Redispersible Emulsion Powder in Ceramic Tile Adhesive

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New Earth Group


Effect of Redispersible Emulsion Powder in Ceramic Tile Adhesive

  redispersible rubber powderOr emulsions, which are very different from hydraulic mineral cementitious materials, it is surprising that the combination of these two types of materials can produce a new material completely different from traditional cement mortar by adding only a few weight percent of white polymer powder. It is the modification effect of this product on mortar that finally establishes the construction process of today's thin layer tile adhesive. Compared with previous construction operations, this is a very economical method in terms of both time and materials. In the early thirties, patents for the modification of gelling systems using synthetic polymer emulsions were first recorded. Less than thirty years later, this product was available in various forms of powder. These products make the operation of the construction site easier and finally open the market.
Various direct and indirect effects of redispersible powder on the bond strength of tile adhesives: on the one hand, the latex film forms a flexible connection between the mortar and the tile, on the other hand, the redispersible powder in the fresh mortar increases the air content and affects the formation and wettability of the surface. Subsequently, during the setting process, the redispersible rubber powder will also affect the shrinkage behavior and the hydration process of the cement. All these parameters, which are influenced by the redispersible powder, contribute to the bond strength.
During the mixing process, the powder particles will be re-dispersed into the whole fresh mortar without coalescing with the cement particles. The "lubrication" of the redispersible rubber powder particles makes the mortar mixture have good fluidity, so as to obtain better construction performance. In addition, the air-entraining effect of the redispersible powder makes the mortar compressible, making it easier to trowel. Depending on the type of redispersible rubber powder, a more plastic or more viscous modified mortar can be obtained.
The cellulose ether and the redispersible rubber powder can keep the water in the mortar. Some of this water will be lost due to drying to escape the pores. The remainder is consumed by the hydration of the cement, creating gel pores. Therefore, the number of gel pores reflects the degree of hydration. The addition of 0.4 weight percent cellulose ether (as a proportion of the plain mortar) will reduce the degree of hydration. Compared with dense concrete, the total porosity of the tile adhesive is unbelievably high, exceeding 40% by volume. Such a high porosity is not problematic, however, since the tile adhesive is not subjected to high compressive stresses. To further improve workability, tile adhesives generally contain very fine-grained fillers, but the finer the filler, the higher the water requirement.
The addition of redispersible rubber powder has a positive effect on the development of bond strength. The tensile strength of the polymer film is an order of magnitude higher than that of the plain mortar. Therefore, the tensile strength (cohesive strength) of mortar can be improved by adding redispersible rubber powder. A soft, high tensile strength polymer film can be bonded to a smooth vitreous tile surface, resulting in improved properties of the mortar, including excellent bond strength. Polymer and cement co-exist in a new composite material with excellent properties, which exhibits high quality and new properties.

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