Influence of Cellulose Ethers on the Consistency, Water Retention and Adhesion of Renovating Plasters

Cellulose ethers such as (hydroxypropyl)methyl cellulose (HPMC), (hydroxyethyl)methyl cellulose (HEMC), methyl ethyl hydroxyethyl cellulose (MEHEC) are currently used admixtures in the production of factory-made mortars. They improve such properties as water retention, workability, adhesion to the substrate, open time etc. in the cement-based mortars. The article investigates the impact of physicochemical properties (molecular weight, methods of modification, viscosity) on water retention, rheological properties and the adhesiveness to the substrates of renovation plasters. The research showed that the cellulose viscosity has a greater impact on water retention despite diversified effects of various derivatives of cellulose. The influence of viscosity of cellulose ethers is uneven. The greatest growth of retention was observed with the change of viscosity from 100 mPa.s to 15000 mPa.s. The further growth of viscosity of cellulose admixtures influenced the change of water retention with lower intensity. It was also stated that cellulose ethers improve the adhesion of renovation plasters to the substrates. Particularly beneficial results were obtained in the case of plasters consisting (hydroxypropyl)methyl cellulose(HPMC)-based admixtures.