Effect of straw carbonization on properties of cement-based straw fiber composites

The raw materials of straw fibers were treated by different methods of nitrogen filling and carbonization at different temperatures. The cementitious materials consisted of ordinary Portland cement with strength grade 52.5 and sulphoaluminate cement with a ratio of 3:7. The surface morphology and material analysis of the fibers were carried out by means of SEM and EDS. The SiO2 content in the surface layer of carbonized straw fibers was 86.69% higher than that of common straw fibers, and the interfacial bonding of the composites was more compact because of the hydration reaction. The initial setting time of composites with carbonized straw fibers is shorter than that of ordinary straw fibers, the flexural strength is slightly reduced by 6.3%, and the compressive strength is significantly increased by 21.93%.