Eco-friendly unfired clay materials modified by natural polysaccharides

Abstract

This study is devoted to the evaluation of the effect of natural polysaccharide (starch, alginate, and chitosan) solutions on the properties of clay composite. The authors describe the technology for obtaining gelated biopolymers (using hot and cold-water treatment and, acid treatment), as well as some characteristics of the obtained solutions, such as viscosity and pH. Some characteristics, such as bulk density, shrinkage, compressive strength, hygroscopic behavior, and water erosion resistance, are determined for the clay composites modified with biopolymer solutions. With increasing the concentration of biopolymer in solution, the bulk density and shrinkage values of the clay composite materials decrease. Also, the application of starch (2.5–10%) and alginate (2.5–7.5%) solutions has a positive effect on the compressive strength of the clay composite, with an increasing about 18–42%. Moreover, the addition of biopolymer solutions leads to an increase in the moisture adsorption degree of clay composites up to 34.2%. Finally, some biopolymers affect the structure and change the water erosion behaviour of clay composite.