Hydroxypropyl Methylcellulose (HPMC) plays a vital role in dry-mixed ready-mixed mortar. Dry mixed ready-mixed mortar is a dry powdery material made by mixing aggregates, cement, fillers and various additives in a certain proportion. It can be used at the construction site by just adding water and stirring. As a highly efficient cellulose ether, HPMC plays multiple functions in dry-mixed ready-mixed mortars, thereby significantly improving the performance of the mortars.
1. Water retention
The main function of HPMC is to improve the water retention of mortar. Since cellulose molecules contain a large number of hydroxyl and methoxy groups, they can form hydrogen bonds with water molecules, thereby enhancing the water retention capacity of the mortar. Good water retention allows the moisture in the mortar to be kept from rapid evaporation for a longer period of time, which is crucial for extending the opening time, improving construction performance, reducing cracks and improving the strength of the mortar. Especially in the construction of high-temperature or low-water-absorbent substrates, the water retention effect of HPMC is more obvious.
2. Improve construction performance
HPMC gives the mortar excellent construction properties. First, it improves the workability of the mortar, making the mixed mortar more uniform and fine. Secondly, HPMC improves the thixotropy of mortar, that is, the mortar can maintain a certain consistency when stationary, but flows easily under stress. This characteristic makes the mortar have good workability and pumpability during construction, and is easy to apply and smooth. In addition, HPMC can effectively reduce the adhesion of mortar during construction, making construction tools easier to clean.
3. Anti-sag property
During construction on vertical surfaces, mortar tends to sag due to gravity, affecting the construction quality. HPMC can significantly improve the sag resistance of mortar, allowing the mortar to better adhere to the surface of the substrate in the early stages after construction and avoid sagging. This is particularly important for materials such as tile adhesives and plaster mortars that need to be applied to vertical surfaces.
4. Enhance plasticity retention
HPMC can enhance the plasticity retention of mortar, making it less likely to shrink and crack during the curing process. Its mechanism is mainly to increase the moisture content in the mortar by improving the microstructure of the mortar, thereby reducing the evaporation rate of water. In addition, HPMC can also form a certain network structure in the mortar, improve the tensile strength and flexibility of the mortar, and reduce cracks caused by shrinkage of the mortar during the hardening process.
5. Improve bonding strength
HPMC can improve the bond strength of mortar. This is mainly due to the polar groups contained in its molecular structure, which can physically adsorb with molecules on the surface of the substrate and enhance the bonding force between the mortar and the substrate. At the same time, the water retention provided by HPMC also helps the cement hydration reaction to proceed fully, thereby further improving the bonding strength of the mortar.
6. Adjust mortar consistency
HPMC can also adjust the consistency of the mortar so that the mortar achieves proper fluidity and workability after adding water. HPMC with different viscosities can be used in different types of mortars. Choosing the appropriate product according to actual needs can make the mortar easier to control and use during construction.
7. Improve mortar stability
HPMC can improve the stability of mortar and reduce segregation of mortar during mixing and transportation. Due to its high thickening effect, it can stabilize the solid particles in the mortar, prevent settlement and delamination, and keep the mortar in a uniform state during the construction process.
8. Weather resistance
The addition of HPMC can improve the weather resistance of mortar, especially under extreme weather conditions. It can reduce the thermal stress caused by temperature changes in the mortar, thus improving the durability and service life of the mortar.
As an important additive, hydroxypropyl methylcellulose has greatly improved the dry-mix preparatory properties through its excellent water retention, construction performance adjustment, sag resistance, enhanced plasticity retention and bonding strength. The quality and construction performance of mixed mortar. Its application can not only improve the physical properties of mortar, but also improve construction efficiency and reduce construction difficulty, thus being widely used in construction.
Post time: Jul-04-2024