Redispersible latex powder can improve the properties of mortar such as flexural strength and adhesion strength, because it can form a polymer film on the surface of mortar particles. There are pores on the surface of the film, and the surface of the pores is filled with mortar, which reduces the stress concentration. And under the action of external force, it will produce relaxation without breaking. In addition, the mortar forms a rigid skeleton after the cement is hydrated, and the polymer in the skeleton has the function of a movable joint, which is similar to the tissue of the human body. The membrane formed by the polymer can be compared to joints and ligaments, so as to ensure the elasticity and flexibility of the rigid skeleton. toughness.
In the polymer-modified cement mortar system, the continuous and complete polymer film is interwoven with cement paste and sand particles, making the whole mortar finer and denser, and at the same time making the whole an elastic network by filling capillaries and cavities. Therefore, the polymer film can effectively transmit pressure and elastic tension. The polymer film can bridge the shrinkage cracks at the polymer-mortar interface, heal the shrinkage cracks, and improve the sealing and cohesive strength of the mortar. The presence of highly flexible and highly elastic polymer domains improves the flexibility and elasticity of the mortar, providing cohesion and dynamic behavior to the rigid skeleton. When an external force is applied, the microcrack propagation process is delayed due to the improved flexibility and elasticity until higher stresses are reached. The interwoven polymer domains also act as a barrier to the coalescence of microcracks into penetrating cracks. Therefore, the redispersible polymer powder improves the failure stress and failure strain of the material.
Adding latex powder to cement mortar will form a highly flexible and elastic polymer network film, which will significantly improve the performance of the mortar, especially the tensile strength of the mortar will be greatly improved. When an external force is applied, due to the improvement of the overall cohesion of the mortar and the soft elasticity of the polymer, the occurrence of micro-cracks will be offset or slowed down. Through the influence of latexr powder content on the strength of thermal insulation mortar, it is found that the tensile bond strength of thermal insulation mortar increases with the increase of latex powder content; the flexural strength and compressive strength have a certain degree with the increase of latex powder content. The degree of decline, but still meet the requirements of the wall exterior finish.
The cement mortar mixed with latex powder, its 28d bonding strength increases with the increase of latex powder content. With the increase of latex powder content, the bonding ability of cement mortar and old cement concrete surface is improved, which ensures its advantages for repairing cement concrete pavement and other structures. Moreover, the folding ratio of mortar increases with the increase of latex powder content, and the flexibility of surface mortar improves. At the same time, it was also found that with the increase of latex powder content, the elastic modulus of mortar decreased first and then increased. On the whole, with the increase of ash accumulation ratio, the elastic modulus and deformation modulus of mortar are lower than those of ordinary mortar.
Post time: Mar-14-2023