Hydroxypropyl methylcellulose is one of the important cellulose ether additives in the dry mortar, and it has many functions in the mortar. The main function of hydroxypropyl methylcellulose in cement mortar is water retention and thickening. In addition, due to its interaction with the cement system, it can also play a role in air entrainment, retardation, and improvement of tensile bonding strength. effect.
The most important property of hydroxypropyl methylcellulose in mortar is water retention. Hydroxypropyl methylcellulose can be used in almost all mortar products as a cellulose ether admixture in mortar, mainly because of its water retention. Generally speaking, the water retention of hydroxypropyl methylcellulose is related to its viscosity, degree of substitution and particle size.
Hydroxypropyl methyl cellulose is used as a thickening agent, and its thickening effect is related to the degree of substitution, particle size, viscosity and modification degree of hydroxypropyl methyl cellulose. Generally speaking, the higher the substitution degree and viscosity of cellulose ether, and the smaller the particle size, the more obvious the thickening effect.
In hydroxypropyl methylcellulose, the introduction of methoxy groups reduces the surface energy of the aqueous solution containing hydroxypropyl methylcellulose, so that hydroxypropyl methylcellulose has an air-entraining effect on cement mortar. Introducing appropriate air bubbles into the mortar, due to the “ball effect” of air bubbles,
The construction performance of the mortar is improved, and at the same time, the introduction of air bubbles increases the output rate of the mortar. Of course, the amount of entrained air needs to be controlled. When the entrained air is too much, it will have a negative impact on the strength of the mortar.
Hydroxypropyl methylcellulose will delay the setting process of cement, so that the setting and hardening process of cement will be slowed down, and the opening time of mortar will be prolonged accordingly, but this effect is unfavorable for mortar in colder areas.
Hydroxypropyl methylcellulose, as a long-chain polymer substance, can improve the bonding performance with the substrate under the premise of fully maintaining the water content of the slurry after adding it to the cement system.
To sum up, the properties of HPMC in mortar mainly include: water retention, thickening, prolonging setting time, air entrainment, and improving tensile bonding strength.
Post time: Feb-20-2025