Adding hydroxypropyl methylcellulose (HPMC) to mortar can indeed improve its frost resistance. This modifier is an additive widely used in building materials, mainly used to improve the properties of mortar, including frost resistance, adhesion and processability.

Basic properties of HPMC
HPMC is a water-soluble cellulose derivative with good rheological properties, thickening and water retention. After adding HPMC to mortar, it can effectively increase the viscosity of mortar, improve its construction performance, and reduce the water evaporation rate, thereby improving the frost resistance of mortar.

Mechanism of improved frost resistance
Enhanced water retention: The high water retention of HPMC can reduce the evaporation of water in the mortar and keep the mortar moist during the hardening process. This helps the hydration reaction of cement, enhances the strength of the mortar, and improves the frost resistance.

Microstructure optimization: The microscopic network structure formed by HPMC in the mortar can effectively disperse and fix water, thereby reducing the formation and growth of ice crystals. This microstructure can keep the mortar stable during freezing and thawing, reducing volume changes and cracks caused by temperature changes.

Reduce porosity: HPMC can reduce the porosity of mortar and reduce the chance of water penetration. This is crucial for frost resistance, because fewer pores mean that water is less likely to accumulate in the mortar at low temperatures, reducing the risk of expansion and damage caused by freezing.

Increase toughness: The addition of HPMC can improve the toughness of the mortar and enhance its ability to resist external forces and temperature changes. This toughness enables the mortar to better adapt to stress during freeze-thaw cycles and reduce the possibility of damage.

Experimental and research results
Several studies have shown that adding an appropriate amount of HPMC to mortar can significantly improve its frost resistance. For example, experimental results show that at -20°C, the mortar with HPMC added has an anti-freeze performance of more than 30% compared to the mortar without HPMC. In addition, the study also found that different varieties and different dosages of HPMC have different effects on the frost resistance of mortar, so in actual applications, it needs to be adjusted according to specific circumstances.

Precautions in practical application
Dosage control: Although HPMC can improve the frost resistance of mortar, its dosage needs to be reasonably controlled. Excessive addition may cause the strength of mortar to decrease, which will affect its overall performance. Therefore, it is usually recommended to test according to the specific ratio and environmental conditions.

Compatibility with other additives: When preparing mortar, if other types of additives are used at the same time, it is necessary to pay attention to the compatibility between them to avoid negative effects.

Influence of construction environment: Environmental conditions during construction (such as temperature, humidity, etc.) will also affect the effect of HPMC. When constructing in a low temperature environment, reasonably adjust the ratio and construction method to ensure the best performance of the mortar.

The application of HPMC in mortar can indeed effectively improve its frost resistance, mainly through mechanisms such as enhancing water retention, optimizing microstructure, reducing porosity and improving toughness. In order to ensure that the frost resistance of the mortar achieves the expected effect, it is recommended to test and optimize in actual application to achieve the best engineering performance.