Water retention: HPMC, as a water retainer, can prevent excessive evaporation and loss of water during the curing process. This water retention property ensures sufficient hydration of cement and improves the strength and durability of the mortar. In high temperature environments, the water retention of HPMC is particularly important to prevent the mortar from losing water too quickly, thereby ensuring the workability of the mortar.
Workability: HPMC has a great impact on the workability of the mortar. By transmitting lubrication, it can reduce the friction between particles, making it easier to apply. This improved workability ensures a more efficient construction process.
Reduce shrinkage and cracks: Shrinkage and cracks are common challenges in mortar applications, resulting in durability being affected. HPMC forms a flexible matrix in the mortar, reducing internal stress and minimizing the occurrence of shrinkage cracks, thereby improving the overall durability of the mortar.
Improve flexural strength: HPMC increases the flexural strength of the mortar by strengthening the matrix and improving the bonding between particles. This will improve the ability to resist external pressure and ensure the structural stability of the building.
Thermal properties: The addition of HPMC can produce a lighter material with a weight reduction of 11.76%. This high porosity helps with thermal insulation and can reduce the conductivity of the material by up to 30% while maintaining a fixed heat flux of about 49W when subjected to the same heat flux. The heat transfer resistance through the panel varies with the amount of HPMC added, and the highest amount of additives results in a 32.6% increase in thermal resistance compared to the reference mixture.
Air entrainment: HPMC can reduce the surface energy of the aqueous solution due to the presence of alkyl groups, increase the gas content in the dispersion, and the toughness of the bubble film is higher than that of pure water bubbles, making it difficult to discharge. This air entrainment may reduce the flexural and compressive strength of the cement mortar specimens, but it will also increase the water retention of the mortar.
Effect of temperature on gelation: Studies have shown that the equilibrium swelling degree of HPMC hydrogel decreases with increasing temperature. Temperature has a significant effect on the swelling behavior of HPMC hydrogel, which may affect its mortar properties at different temperatures.
Effect of temperature and polymer concentration on wetting ability: Changes in temperature and HPMC concentration affect the dynamic surface tension and wetting ability of its aqueous solution. As the concentration of HPMC increases, the dynamic contact angle value of the solution also increases, thereby reducing the spreading behavior of the Avicel tablet surface.
HPMC has a significant effect on the performance of mortar at different temperatures, and can improve the water retention of mortar, improve workability, improve crack resistance, enhance bonding strength, improve durability, reduce shrinkage and cracks, improve water resistance and impermeability, improve freeze-thaw resistance, and improve tensile bond strength. These characteristics make HPMC an important additive to improve the durability of mortar.