1. Overview of HPMC
HPMC (Hydroxypropyl Methylcellulose, hydroxypropyl methylcellulose) is a non-ionic cellulose ether that is widely used in construction, coatings, medicine, cosmetics and other fields. The molecular structure of HPMC contains water-soluble hydroxypropyl and methyl groups, giving it unique thickening, film-forming, water retention, dispersion and other properties. In the construction industry, HPMC, as an important additive, is often used in the production of concrete, mortar and other building materials. Especially in machine-blasted mortar, the addition of HPMC can significantly improve the construction performance and quality of mortar.

2. The role of HPMC in machine-blasted mortar
Machine-blasted mortar is a construction method that uses spraying equipment to spray mortar onto walls or other building surfaces. Compared with traditional manual plastering, it has the advantages of high construction efficiency and labor saving. However, machine-blasted mortar often encounters some problems during the construction process, such as poor mortar fluidity, insufficient adhesion, and poor pumping performance. These problems will affect construction efficiency and quality.

The main functions of HPMC in machine-blasted mortar include:

Thickening effect: As a thickening agent, HPMC can increase the viscosity of the mortar, thereby improving the pumping performance of the mortar, preventing the mortar from layering and flowing during the spraying process, and ensuring uniform spraying.

Water retention: HPMC has good water retention performance, which can effectively delay the evaporation of water in the mortar, ensure the adhesion of the mortar during the construction process, and avoid problems such as cracks and holes in the mortar due to rapid water evaporation.

Improve adhesion: HPMC can enhance the adhesion between the mortar and the base surface, improve the adhesion and resistance to falling off of the mortar, and ensure that the mortar is firmly attached to the construction surface.

Improve construction performance: HPMC can improve the fluidity of mortar, making it easier to operate, especially during machine spraying, it can ensure the uniformity and flatness of spraying.

3. The proportion of HPMC in machine-blasted mortar
The proportion of HPMC has an important influence on the performance of machine-blasted mortar. The appropriate amount of HPMC can not only improve the construction performance of the mortar, but also ensure its final hardening effect. Normally, the amount of HPMC added should be adjusted according to the specific mortar formula and construction requirements. Generally speaking, the addition amount of HPMC is usually between 0.1% and 0.5% of the weight of cement. The specific ratio needs to consider the following factors:

Types of mortar: Different types of mortar (such as ordinary mortar, exterior wall mortar, insulation mortar, etc.) have different needs for HPMC. For exterior wall insulation mortar or high-strength mortar, a slightly higher HPMC dosage may be required to ensure its adhesion and water retention.

Climatic conditions: When constructing in a high temperature and dry environment, the water in the mortar evaporates quickly. An appropriate increase in the amount of HPMC can effectively prevent the mortar from drying out. In humid environments, appropriately reducing the amount of HPMC used can help avoid bleeding caused by excessive water retention in the mortar.

Construction methods: Different construction methods have different requirements for the fluidity and adhesion of mortar. If high-pressure spraying is used, the proportion of HPMC may need to be adjusted to ensure that the mortar has better fluidity and spraying stability.

Basic materials: The properties of different batches of cement, sand, stone and other basic materials may be different, and the proportion of HPMC should also be fine-tuned based on the actual conditions of these materials.

4. Application examples of HPMC in machine-blasted mortar
In practical applications, HPMC is widely used in different types of machine-blasted mortars. For example, in exterior wall insulation mortar, HPMC as a thickener and water-retaining agent can effectively improve the adhesion and crack resistance of the mortar, ensuring the firmness and durability of the insulation layer; in waterproof mortar, HPMC can improve the water resistance of the mortar. Permeability ensures that the wall surface is not eroded by water; in decorative mortar, HPMC can improve the flatness and construction performance of the mortar and enhance the operability during the spraying process.

In these applications, the proportion of HPMC not only depends on the purpose of the mortar, but also takes into account many factors such as construction equipment, construction environment, and construction technology. Through scientific proportioning, the mortar can be ensured to have the best performance during the construction process and achieve the desired effect.

As an important construction additive, HPMC is increasingly used in machine-blasted mortar. It significantly improves the construction performance and final effect of machine-blasted mortar by improving the fluidity, adhesion and water retention of the mortar. In order to achieve the best construction effect, the proportion of HPMC needs to be adjusted according to various factors such as the type of mortar, climate conditions, and construction methods. In practical applications, a scientific and reasonable HPMC ratio can ensure the quality and construction efficiency of machine-blasted mortar and meet the high requirements for mortar performance in modern building construction.