Sodium Carboxymethyl Cellulose, usually shortened as CMC, has been a common additive used in many industries, such as food, pharmaceutical, detergent, ceramic, paper-making, textile, painting, mining and oil-drilling industries etc. It has also been used in construction industry nowadays. Let’s talk about the role of CMC in mortar for construction industry.
1. Water retention: CMC can help avoid water infiltration into the wall. The appropriate amount of water stays in the mortar so that the cement has a longer time for hydration. Water retention is proportional to the viscosity of cellulose ether solution in mortar. The higher the viscosity, the better the water retention is. As water molecules rise, water retention decreases. Because for the same amount of carboxymethyl cellulose solution, water increase means decrease in viscosity. The improvement of water retention will prolong the curing time of the mortar.
2. Lubrication ability: All air entraining agent has the effect of wetting agent because its reduction of surface tension can help the fine powder in motar disperse when mixed with water.
3. Bubble content: High bubble content leads to better mortar yield and can reduce the formation of cracks. Bubble content usually depends on stirring time. CMC is widely used to improve the properties of building materials, such as cement and gypsum. In cement-based grout, it can improve water retention, prolong opening time and reduce sagging phenomenon.
4. Good anti-sagging mortar means that there is no danger of flow hanging or downward flow when constructed with thick layer. The newly developed construction grade CMC can provide better flow resistance of mortar.
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