Hydroxypropyl methylcellulose

Hydroxypropyl methylcellulose (HPMC) is a non-ionic cellulose ether made from cellulose, a natural polymer material, which is produced through a series of chemical processes.

This is an odorless, odorless, non-toxic white powder that can be dissolved in cold water to form a transparent, viscous solution.

With thickening, adhesion, dispersion, emulsification, film formation, suspension, adsorption, gelation, surface activity, retention of moisture and protection of colloids.

In mortar, an important role of hydroxypropyl methylcellulose is water retention, which is the ability of the mortar to retain water.

1. The importance of water retention for mortar

Mortar with poor water retention is easy to bleed and segregate during transportation and storage. That is, the water floats on the top, and the sand and cement sink below. It must be stir again before use.

Mortar with poor water retention, in the application process, as long as the ready-mixed mortar is in contact with the block or the base layer, the ready-mixed mortar will be absorbed by the water.

At the same time, the external surface of the mortar evaporates moisture into the atmosphere, which causes the mortar to lose water due to water loss, which affects the further hydration of the cement.

At the same time, it affects the normal development of the strength of the mortar, which causes the strength, especially the interface strength between the hardened body of the mortar and the base layer to become lower, causing the mortar to crack and fall.

2. Traditional methods for improving water retention of mortar

The traditional solution is to water the grass, but it is impossible to ensure that the grass is evenly moist. The ideal hydration goal of the cement mortar on the base layer is: the cement hydration product is accompanied by the process of the base layer absorbing water.

It penetrates into the base layer and forms an effective “key connection” with the base layer to achieve the required bond strength. Direct watering on the surface of the grassroots will cause the water absorption of the grassroots to be severely dispersed due to the difference in air temperature, watering time, and watering uniformity.

The base layer absorbs less water and will continue to absorb the water in the mortar. Before the cement hydration takes place, the water is absorb.

Affects the penetration of cement hydration and hydration products into the substrate; the base layer absorbs a large amount of water, and the water in the mortar migrates slowly to the substrate. Even a water-rich layer is forme between the mortar and the substrate, which also affects the bond strength.

Therefore, the common method of watering the base layer can not only effectively solve the problem of high water absorption of the base layer of the wall. Instead, it will affect the bonding strength of the mortar and the base layer, causing hollowing and dry cracking.

3. The role of efficient water retention

(1) Excellent water retention makes the mortar open longer. It has the advantages of large-area construction, long use time in the barrel, batch mixing and batch use, etc.

(2) Good water retention performance makes the cement in the mortar fully hydrated and effectively improves the mortar’s bonding performance.

(3) The mortar has excellent water retention properties, making it difficult for the mortar to produce segregation and bleeding. Now, the workability and workability of the mortar are improve.

If you have any questions, you can send them to my email: tanyatao@qinahaochem.com

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