| Abstract [eng] |
This Master’s thesis investigates the properties of novel cement – sawdust composites in which wood sawdust is treated with special mineral additives. The topic is relevant in the context of increasingly stringent sustainability requirements in construction, the growing demand for renewable materials, and the objective of reducing the negative environmental impact of the construction sector. The aim of the thesis is to examine how the pre – treatment of wood sawdust affects the physical and mechanical properties of cement-based composite materials and to compare three different chemical treatment methods for wood particles. The objectives of the study are: to determine the influence of wood sawdust treatment on the mechanical properties of the composite; to evaluate how these treatments affect the water absorption properties of the composite; to identify which composite specimen exhibits the best thermal conductivity properties; and to compare the amount of CO₂ emissions generated during the production process of the composite. The research includes a literature review to identify the negative environmental impact of cement-based materials and to define the properties of cement – wood sawdust composites, as well as to assess how chemical treatment of wood sawdust influences composite performance. Experimental investigations are conducted to determine the density, compressive strength, flexural strength, water absorption, and thermal conductivity of the formed cement composites containing mineral – additive – treated wood sawdust, and to calculate their CO₂ footprint. All tests are carried out in accordance with LST EN standards. A comparison of the experimental results shows that treatment of wood sawdust with special mineral additives significantly affects the properties of the composite. However, the strength of the control mixture was not achieved. The best mechanical properties were obtained in specimens treated with a combination of sodium hydroxide, calcium hydroxide, silicon dioxide, and metakaolin, resulting in approximately 46% higher compressive strength, about 17% higher flexural strength, and around 36% lower water absorption compared to other mineral additive treatment combinations. The best thermal conductivity was achieved by specimens treated with a combination of sodium silicate and phosphogypsum, reaching 0,185 W/mK. These results demonstrate that cement composites incorporating chemically treated wood sawdust can be a competitive alternative to less environmentally friendly products currently available on the market. |
