What is the water retention of methyl cellulose ether (MC)

What is the water retention of methyl cellulose ether (MC)

Answer: The level of water retention is one of the important indicators to measure the quality of methyl cellulose ether, especially in the thin layer construction of cement-based and gypsum-based mortar. Enhanced water retention can effectively prevent the phenomenon of strength loss and cracking caused by excessive drying and insufficient hydration. The excellent water retention of methyl cellulose ether under high temperature conditions is one of the important indicators to distinguish the performance of methyl cellulose ether. Under normal circumstances, most common methyl cellulose ethers decrease their water retention as the temperature rises. When the temperature rises to 40°C, the water retention of common methyl cellulose ethers is greatly reduced, which is very important in hot and dry areas And the thin-layer construction on the sunny side in summer will have a serious impact. However, making up for the lack of water retention through high dosage will cause high viscosity of the material due to high dosage, which will cause inconvenience to construction.

Water retention is very important to optimize the hardening process of mineral gelling systems. Under the action of cellulose ether, the water is gradually released to the base layer or the air over a prolonged period of time, thus ensuring that the cementitious material (cement or gypsum) has a long enough time to interact with water and gradually harden.

What are the properties of methyl cellulose ether?

Answer: Only a small amount of methyl cellulose ether is added, and the specific performance of gypsum mortar will be greatly improved.

(1) Adjust the consistency

Methyl cellulose ether is used as a thickener to adjust the consistency of the system.

(2) Adjust water demand

In the gypsum mortar system, water demand is an important parameter. The basic water requirement, and the associated mortar output, depends on the formulation of the gypsum mortar, i.e. the amount of limestone, perlite, etc. added. The incorporation of methyl cellulose ether can effectively adjust the water demand and mortar output of gypsum mortar.

(3) Water retention

The water retention of methyl cellulose ether, one can adjust the opening time and coagulation process of the gypsum mortar system, so as to adjust the operating time of the system; the two methyl cellulose ether can gradually release water over a long period of time The ability to effectively ensure the bonding between the product and the substrate.

(4) Adjust the rheology

The addition of methyl cellulose ether can effectively adjust the rheology of the plastering gypsum system, thereby improving the working performance: the gypsum mortar has better workability, better anti-sag performance, no adhesion with construction tools and higher pulping performance, etc.

How to choose the suitable methyl cellulose ether?

Answer: Methyl cellulose ether products have different characteristics according to their etherification method, degree of etherification, viscosity of aqueous solution, physical properties such as particle fineness, solubility characteristics and modification methods. To get the best use effect, it is necessary to choose the correct brand of cellulose ether for different application fields, and the selected brand of methyl cellulose ether must be compatible with the mortar system used.

Methyl cellulose ethers are available in different viscosities to suit various needs. Methyl cellulose ether can only play a role after being dissolved, and its dissolution rate must be adapted to the application field and construction process. The fine powder product is suitable for dry-mixed mortar systems (such as spray plastering plaster). The extremely fine particles of methyl cellulose ether can ensure rapid dissolution, so that its excellent performance can be effectively exerted in a short time after the formation of wet mortar. It increases the consistency and water retention of mortar in a very short time. This feature is especially suitable for mechanical construction, because in general, the mixing time of water and dry-mix mortar is very short during mechanical construction.

What is the water retention of methyl cellulose ether?

Answer: The most important performance of different grades of methyl cellulose ether (MC) is their water retention capacity in building material systems. In order to obtain good workability, it is necessary to keep enough moisture in the mortar for a long time. Because water acts as a lubricant and solvent between the inorganic components, thin-layer mortars can be carded and plastered mortars can be spread with trowels. Absorbent walls or tiles do not need to be pre-wetted after using cellulose ether-added mortar. So MC can bring fast and economical construction results.

In order to set, cementitious materials such as gypsum need to be hydrated with water. A reasonable amount of MC can keep the moisture in the mortar for a long enough time, so that the setting and hardening process can continue. The amount of MC required to obtain sufficient water retention capacity depends on the absorptivity of the base, the composition of the mortar, the thickness of the mortar layer, the water demand of the mortar, and the setting time of the cementitious material.

The finer the particle size of MC, the faster the mortar thickens.