Designing of Sustainable Building Material Made of Non-Fired Clay with Various Biopolymers ^†

This study is dedicated to the development of an environmentally friendly building material made from non-fired clay, stabilized with various biopolymers (starch, alginate, and chitosan). The efficacy of the application of natural polymers has already been proven in the geotechnical industry for soil stabilization [1,2,3]. The authors believe that the use of natural polymers will have a positive impact on the physical–mechanical and operational properties of the newly obtained building material made from non-fired clay. With the addition of different concentrations (2.5%, 5%, 7.5%, and 10%) of biopolymer solutions, the density of the clay composites was reduced by up to 9% (from 1990 to 1810 kg/m³). The inclusion of starch and alginate contributed to an increase in the strength of the clay composite of up to 42% (from 6.6 to 9.4 MPa). However, the application of 10% chitosan resulted in a 20% decrease in strength (from 6.6 to 5.3 MPa). The conducted research confirms that biopolymers are a promising stabilizer for non-fired clay composites. Nevertheless, to create an effective building material, it is essential to consider the type of clay and biopolymer, as well as their interaction potential and compatibility.