Impact of guar gum and chitosan ethers on physico-mechanical properties and durability of natural hydraulic lime mortars

Impact of guar gum and chitosan ethers on physico-mechanical properties and durability of natural hydraulic lime mortars

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The addittion of guar gum derivatives and chitosan ethers has been studied in the natural hydraulic lime (NHL) mortars. These types of polysaccharides can be possibly used as viscosity enhancing admixtures or water retaining agents for the mortars instead of cellulose ethers. The water retention capacity is an essential property of the mortars to enhance the hydration of NHL and mortar adhesion to the substrate. The main part of this study is addressed to the physico-mechanical properties, microstructure, and durability of NHL mortars. The hydroxypropyl- derivatives showed air-entraining function, which is beneficial for the durability of mortars and affects porosity of mortars, as well as water absorption coefficient. The biopolymer addition slightly improved initial flexural strength with the increasing difference for later ages, the only exception being hydroxypropyl guar, which showed slight decrease of flexural strength. Compressive strength decreased by the addition of biopolymeric admixture in all cases; the degree od decrease was dependent on the type and dosage of the admixture.

The addittion of guar gum derivatives and chitosan ethers has been studied in the natural hydraulic lime (NHL) mortars. These types of polysaccharides can be possibly used as viscosity enhancing admixtures or water retaining agents for the mortars instead of cellulose ethers. The water retention capacity is an essential property of the mortars to enhance the hydration of NHL and mortar adhesion to the substrate. The main part of this study is addressed to the physico-mechanical properties, microstructure, and durability of NHL mortars. The hydroxypropyl- derivatives showed air-entraining function, which is beneficial for the durability of mortars and affects porosity of mortars, as well as water absorption coefficient. The biopolymer addition slightly improved initial flexural strength with the increasing difference for later ages, the only exception being hydroxypropyl guar, which showed slight decrease of flexural strength. Compressive strength decreased by the addition of biopolymeric admixture in all cases; the degree od decrease was dependent on the type and dosage of the admixture.