Controlling the application performance
of cement renders with cellulose ethers
Summary: Cellulose ethers are an indispensable component of a cement render formulation. This highly functional additive helps to adjust the performance profile of the render at various levels. The main role of the cellulose ether is to provide sufficient water retention to the render so that the cement can set and develop strength before it dries out. The dissolved cellulose ether in the mortar matrix determines to a large extent its rheological properties and subsequently the workability of the render. Depending on the substitution level cellulose ethers have a delaying impact on the cement setting rate. This article discusses the effect of the structural parameters of the cellulose ether on all performance aspects of cement renders.
Cellulose ethers are well defined by their molecular weight, by the type and the degree of substitution. The effect of cellulose ethers on specific performance aspects of cement mortars has been investigated in the past. Its main effect is the water retention in mortar systems which can be adjusted by the dosage and the molecular weight of the cellulose ether [1]. The cellulose ethers preferred in dry-mix mortar application are hydroxypropyl methyl cellulose (HPMC) or hydroxyethyl methyl cellulose (HEMC). Aqueous solutions of this type of polysaccharides reversibly precipitate or...
