Application of Cellulose Ether in Mortar
Water retention in mortar is the ability to retain water, which is enhanced by cellulose ether. The viscosity of cellulose ether directly affects its water retention properties, with higher viscosity resulting in better water retention.
Cellulose Ether Water Retention
The water retention of mortar is a critical property that influences its performance. Kingmax Cellulose ether, a commonly used additive in mortar, improves water retention by forming hydrogen bonds with water molecules. The hydroxyl and ether bonds in cellulose provide oxygen atoms that interact with water molecules, forming hydrogen bonds that transform free water into bound and entangled water. The viscosity of cellulose ether is directly related to its water retention properties, with higher viscosity leading to better water retention.
Solubility of Cellulose Ether
Cellulose ether is a widely used additive in various applications, including mortar, due to its ability to improve water retention and other properties. However, the particle size of cellulose ether significantly affects its performance in water. Coarser particles of cellulose ether are easy to disperse in water without agglomeration, but their dissolution rate is slow, requiring up to 60 minutes to dissolve. On the other hand, fine cellulose ether particles are easy to disperse in water without agglomeration, and their dissolution rate is moderate, requiring only about 3 minutes to dissolve. Cellulose ether ultrafine particles disperse quickly in water, dissolve quickly, and form viscosity rapidly, requiring only 10-30 seconds to dissolve. The finer the cellulose ether particles, the better the water retention. When coarse particles of cellulose ether come into contact with water, the contact surface dissolves and forms a gel that wraps around the material, preventing water molecules from constantly penetrating. Stirring for a long time may lead to uneven dispersion and dissolution, forming a cloudy flocculent solution or agglomerates. In contrast, fine cellulose ether particles disperse and dissolve immediately upon contact with water, forming a uniform viscosity. In summary, the particle size of cellulose ether plays a critical role in its performance, with finer particles showing better water retention and faster dissolution rates.
PH Value of Cellulose Ether (flame Retardant or Early Strength Effect)
The pH value of cellulose ether manufacturers both domestically and abroad is generally controlled at around 7, which indicates an acidic state. This is due to the presence of a large number of glucose ring structures in the molecular structure of cellulose ether, which contain an anhydroglucose ring that is the main group responsible for cement retardation. The anhydroglucose ring interacts with hydrated calcium in the cement hydration solution, reducing the concentration of calcium ions during the induction period of cement hydration, preventing the precipitation of calcium hydroxide and calcium crystals, and delaying the hydration of the cement process. To adjust the pH value, most manufacturers now use sodium carbonate, which is a quick-setting agent that improves the performance of cellulose ether on the surface of cement particles. Sodium carbonate promotes the further increase of the cohesion of particles, improving the viscosity of mortar. Additionally, sodium carbonate quickly combines with calcium ions in the cement, promoting the formation of ettringite and causing the cement to condense rapidly, resulting in early-strength mortar. However, the pH value should be adjusted according to different customer requirements in the actual production process. The adjustment of pH value plays a crucial role in controlling the cement setting time and ultimately affecting the quality and performance of the mortar. Therefore, it is essential to use an appropriate pH value to ensure optimal performance in mortar production.
The Air Permeability of Cellulose Ether
Cellulose ether can induce gas entrainment due to its surface activity, which lowers the surface tension and interfacial energy of water, creating tiny bubbles during stirring. Additionally, the cellulose ether gel formation in the mortar enhances its compactness and elastic filling by filling in the voids and reinforcing the structure. However, when the substrate is compressed, the lack of rigid support leads to decreased strength and folding rate of the mortar. The methoxyl and hydroxypropyl groups in cellulose ether’s molecular chain facilitate its dissolution in the mortar and formation of a thick gel with calcium and aluminum ions. This gel improves the mortar’s overall performance and contributes to its water retention ability. However, it is essential to note that the optimal cellulose ether concentration must be used to avoid a decrease in strength or the presence of excess air pockets.
Film-forming Properties of Cellulose Ether
Cellulose ether plays an important role in improving the quality of dry-mixed mortar. By forming a thin layer of latex film, it can seal the surface and prevent the dry mortar phenomenon. The water retention property of cellulose ether allows for the storage of water molecules in the mortar, which promotes the full development of cement hydration and strength, thereby enhancing the bonding strength of the mortar. Additionally, cellulose ether increases the viscosity of the mortar and improves its plasticity.
Furthermore, the interfacial activity of cellulose ether mainly occurs at the gas-liquid-solid interface. This allows for the introduction of air bubbles, followed by their dispersion and wetting. The alkyl group present in cellulose ether reduces the surface tension and interfacial energy of water, resulting in the generation of many tiny closed bubbles during the stirring process of the aqueous solution. As a result, the mortar has good workability and improved quality due to the addition of Kingmax cellulose ether.
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