Why add redispersible latex powder in self-leveling mortar

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"Why add redispersible latex powder in self-leveling mortar
Due to the particularity of self-leveling floor construction: self-leveling layer is secondary additional layer; construction thickness is usually thinner than the general floor mortar; after construction, for rapid delivery, usually do not do maintenance or maintenance time is very short; self-leveling layer need to resist the thermal stress from different materials; sometimes self-leveling material is used for difficult to attach the base surface. Therefore, even if there is the auxiliary effect of the interface treatment agent, in order to ensure that the self-leveling layer can be firmly attached to the base for a long time, adding a certain amount of latex powder can ensure that the self-leveling material has long-term and reliable bonding force. No matter on the absorbent base surface (such as commercial concrete), organic base surface (such as wood) or non-absorbent base surface (such as metal, such as ship deck), the bond strength of self-leveling material is significantly improved with the increase of latex powder content. Taking the failure form as an example, the bond strength test of self-leveling material mixed with latex powder occurs in the self-leveling material or in the base surface, but not in the interface, it shows that its adhesion is good.
Although the wear resistance of the bottom self-leveling material is not as high as that of the surface layer, because the ground inevitably has to bear various dynamic and static stresses [from furniture casters, forklifts (such as warehouses) and wheels (such as parking lots), etc.], a certain wear resistance is one of the important properties of the long-term durability of the self-leveling ground, the increase in the amount of latex powder, the wear resistance of the self-leveling material is significantly improved; however, the self-leveling material without latex powder has worn through the bottom after 7 days of laboratory curing and only 4800 times of reciprocating rolling. This is because the latex powder enhances the cohesion of the self-leveling material and improves the plasticity (I. e., deformability) of the self-leveling material, so that it can well disperse the dynamic stress from the roller.
The content of latex powder increases the tensile strength and elongation at break of self leveling floor materials. With the increase of latex powder content, the cohesion (tensile strength) of self-leveling materials has been significantly improved, and the flexibility and variability of cement-based self-leveling materials have also been significantly improved. This is consistent with the tensile strength of latex powder itself is more than 10 times that of cement. From the test results, when the content is 4%, the tensile strength increases by more than 180% and the elongation at break increases by more than 200%. From the point of view of health and comfort, this increase in flexibility is beneficial to reduce noise and improve the fatigue of the human body standing on it for a long time.
Under the condition of constant water-cement ratio and air content, the amount of latex powder has a strong influence on the flexural and compressive strength of cement-based flooring materials. With the increase of latex powder content, the compressive strength decreased slightly, while the flexural strength increased significantly, that is, the compression ratio (compressive strength/flexural strength) decreased gradually. This reflects the brittleness of self-leveling floor materials with the increase of latex powder content decreased significantly. This will reduce the elastic modulus of self leveling floor material, improve its crack resistance.
Self-leveling mortar products are complex, and their various properties can be significantly improved by adding latex powder. It can play an important role in increasing the tensile strength, flexibility and adhesion of self leveling floor materials. Adding redispersible emulsion powder can improve the water retention performance of fresh cement mortar, as well as the bonding performance, flexibility, impermeability and corrosion resistance of hardened cement mortar."

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Redispersible latex powder