Cellulose ether can significantly improve the performance of wet mortar, and it is a main additive that affects the construction performance of mortar. Reasonable selection of cellulose ethers of different varieties, different viscosities, different particle sizes, different degrees of viscosity and added amounts will have a positive impact on the improvement of the performance of dry mix mortar.
There is also a good linear relationship between the consistency of cement paste and the dosage of cellulose ether. Cellulose ether can greatly increase the viscosity of mortar. The larger the dosage, the more obvious the effect. High-viscosity cellulose ether aqueous solution has high thixotropy, which is also a major characteristic of cellulose ether.
The thickening effect depends on the degree of polymerization of cellulose ether, solution concentration, shear rate, temperature and other conditions. The gelling property of the solution is unique to alkyl cellulose and its modified derivatives. The gelation properties are related to the degree of substitution, solution concentration and additives. For hydroxyalkyl modified derivatives, the gel properties are also related to the modification degree of hydroxyalkyl. 10%-15% solution can be prepared for low-viscosity MC and HPMC, 5%-10% solution can be prepared for medium-viscosity MC and HPMC, and 2%-3% solution can only be prepared for high-viscosity MC and HPMC. Usually the viscosity classification of cellulose ether is also graded by 1%-2% solution.
High-molecular-weight cellulose ether has high thickening efficiency. Polymers with different molecular weights have different viscosities in the same concentration solution. The target viscosity can only be achieved by adding a large amount of low molecular weight cellulose ether. Its viscosity has little dependence on the shear rate, and the high viscosity reaches the target viscosity, and the required addition amount is small, and the viscosity depends on the thickening efficiency. Therefore, to achieve a certain consistency, a certain amount of cellulose ether (concentration of the solution) and solution viscosity must be guaranteed. The gel temperature of the solution also decreases linearly with the increase of the concentration of the solution, and gels at room temperature after reaching a certain concentration. The gelling concentration of HPMC is relatively high at room temperature.
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