According to the different ratio, the use of redispersible polymer powder to modify the dry mixed mortar can improve the bond strength with various substrates, and improve the flexibility and deformability of mortar, bending strength, wear resistance, toughness, bonding force and density, water retention ability and workability.
A large number of tests show that the amount of RD powder is not the more the better. When the content of RD powder is too low, it only plays some plasticizing effect, but the enhancement effect is not obvious. When the amount of RD powder is too large, the strength will decrease. Only when the content of RD powder is moderate, it not only increases the deformation resistance, improves the tensile strength and bond strength, but also improves the permeability and crack resistance. The ratio of lime and sand, the ratio of water and cement, the gradation and type of aggregate, and the characteristics of aggregate will ultimately affect the comprehensive performance of the product.
The influence of redispersible latex powder on the strength of mortar is that the tensile strength and flexural strength of mortar can be significantly increased after the addition of redispersible polymer powder, but the compressive strength has not been significantly improved or even decreased. Due to the toughening effect of redispersible polymer powder, the internal tensile strength and interfacial bonding tensile strength of mortar are improved, and the bonding tensile strength between mortar and substrate is greatly improved.
The cracking of brittle materials is mainly caused by tensile failure, when the tensile stress exceeds its own tensile strength value, cracking will occur. Therefore, having a high tensile strength value is a necessary condition for resistance to cracking.
The results show that the tensile strength of polymer-modified cement mortar generally increases first and then decreases with the increase of cement-cement ratio, which indicates that there is a good mixing range. The reason for the decline is generally due to the addition of excessive redispersible emulsion powder leading to the introduction of too many bubbles, resulting in a downward trend in compressive strength. Therefore, the compressive strength should be improved by adjusting the ratio of lime to sand, water to cement, aggregate gradation and aggregate type. The improvement of tensile strength, flexural strength, flexibility, crack resistance and hydrophobicity can be achieved by adding redispersible latex powder, but the more the addition, the better. When the content of rubber powder is too low, it only plays some plasticizing effect, but the enhancement effect is not obvious. When the amount of redispersible powder is too large, the strength will decrease. Only when the content of redispersible powder is moderate, it not only increases the deformation resistance, tensile strength and bond strength, but also improves the permeability and crack resistance. The ratio of lime and sand, the ratio of water and cement, the gradation and type of aggregate, and the characteristics of aggregate will ultimately affect the comprehensive performance of the product.
Post time: Feb-26-2024