After adding hydroxypropyl methylcellulose to cement-based materials, it can thicken. The amount of hydroxypropyl methylcellulose determines the water demand of cement-based materials, so it will affect the output of mortar.
Several factors affect the viscosity of hydroxypropyl methylcellulose:
1. The higher the degree of polymerization of cellulose ether, the larger its molecular weight, and the higher the viscosity of the aqueous solution;
2. The higher the intake (or concentration) of cellulose ether, the higher the viscosity of its aqueous solution. However, it is necessary to pay attention to selecting the appropriate intake during application to avoid excessive intake, which will affect the work of mortar and concrete. characteristic;
3. Like most liquids, the viscosity of cellulose ether solution will decrease with the increase of temperature, and the higher the concentration of cellulose ether, the greater the influence of temperature;
4. Hydroxypropyl methylcellulose solution is usually a pseudoplastic, which has the property of shear thinning. The greater the shear rate during the test, the lower the viscosity.
Therefore, the cohesion of mortar will decrease due to external force, which is beneficial to the scraping construction of mortar, resulting in good workability and cohesion of mortar at the same time.
The hydroxypropyl methylcellulose solution will show Newtonian fluid characteristics when the concentration is very low and the viscosity is low. When the concentration increases, the solution will gradually show pseudoplastic fluid characteristics, and the higher the concentration, the more obvious the pseudoplasticity.
Post time: Jan-28-2023