China Effect of HPMC on The Setting of Mortar

The addition of HPMC has obvious retarding effect on the mortar mixture, and with the increase of the HPMC content, the setting time of the mortar has been extended. Under the same HPMC content, the mortar formed underwater is better than that formed in the air. The setting time is longer. When measured in water, the setting time of the mortar mixed with HPMC is 6 ~ 18 h delayed compared to the blank test, and the final set is delayed 6 ~ 22 h.
HPMC is a macromolecular polymer with a linear structure of macromolecules and hydroxyl groups on the functional groups, which can form hydrogen bonds with the mixing water molecules to increase the viscosity of the mixing water. The macromolecular chains of HPMC will attract each other, causing the HPMC molecules to entangle with each other to form a network structure, which wraps cement and mixing water. Because HPMC forms a film-like network structure and wraps the cement, it will effectively prevent the evaporation of water in the mortar and hinder or slow down the cement hydration rate.