Hydroxypropyl Methyl Cellulose HPMC Water Retention in Mortar

Hydroxypropyl Methyl Cellulose

HPMC cellulose is important for mortar water retention

Why do people have such high requirements for water retention in mortar? What are the outstanding advantages of mortar with good water retention? Let me introduce to you the importance of mortar water retention.

Necessity of water retention
The water retention of mortar refers to the ability of mortar to retain moisture. 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 re-mixed before use.
All kinds of bases that require mortar for construction have a certain amount of water absorption. If the water retention of the mortar is poor, as long as the pre-mixed mortar is in contact with the block or the base, the pre-mixed mortar will be absorbed. Moisture, and at the same time, the outer surface of the mortar evaporates into the atmosphere, resulting in insufficient water in the mortar due to water loss, affecting the further hydration of the cement, and affecting the normal development of the mortar strength, resulting in strength, especially the interface strength between the mortar hardened body and the base Lowered, causing mortar to crack and fall off. The mortar with good water retention has sufficient cement hydration, normal strength development and good adhesion with the base.
Ready-mixed mortar is usually built between water-absorbing blocks or smeared on the base, forming a whole with the base. The impact of poor mortar water retention on project quality is:
1. Due to excessive water loss of the mortar, which affects the normal coagulation and hardening of the mortar and reduces the adhesion between the mortar and the surface, it is not only inconvenient for construction operations, but also reduces the strength of the masonry, thereby greatly reducing the quality of the project.
2. If the mortar is not holding water well, the water will be easily absorbed by the bricks, making the mortar too dry and uneven. When the project is implemented, it not only affects the progress, but also makes the wall easily cracked due to shrinkage;
Therefore, increasing the water retention of the mortar is not only beneficial to the construction, but also increases the strength.

Traditional water retention method
The traditional solution is to pour water on the base, but it is impossible to ensure that the base is evenly moistened. The ideal hydration goal of cement mortar on the base layer is that the cement hydration products penetrate into the base layer along with the process of the base layer absorbing moisture, forming an effective "key-key connection" with the base layer, so as to achieve the required bonding strength.
Direct watering to the surface of the base layer will cause the water absorption of the base layer to be severely dispersed due to differences in air temperature, watering time, and uniformity of watering. The water absorption of the base is small, and it will continue to absorb the water in the mortar. Before the cement hydration is carried out, the water is absorbed, which affects the cement hydration and the penetration of the hydration products into the matrix; the base absorbs a large amount of water, and the water in the mortar is directed to the base The medium migration speed is slow, and even a water-rich layer is formed between the mortar and the matrix, which also affects the bonding strength. Therefore, the common base watering method can not only effectively solve the problem of high water absorption rate of the wall base, but also affect the bonding strength of the mortar and the base, causing hollowing and dry cracking.

The role of efficient water retention
The high water retention performance of mortar has many advantages:
1. Excellent water retention performance makes the mortar open longer, with the advantages of large-area construction, long use time in the barrel, batch mixing and batch use.
2. Good water retention performance makes the cement in the mortar fully hydrated and effectively improves the adhesion performance of the mortar.
3. The mortar has excellent water-retaining properties so that the mortar is not easy to produce segregation and bleeding. Now, the mortar's workability and workability are improved.