Study on triaxial compression tests on briquette coal specimens with different binder contents

To produce briquette coal with mechanical properties more similar to raw coal,a series of triaxial compression experiments were conducted using different contents of ordinary Portland cement as a binder. The stress-strain relationship,failure mode,and mechanical parameters of various specimens were compared to reveal the influence of binder content on macroscopic mechanical properties. The experimental results indicate that the changes in the compaction stage and elastic stage of different briquette coal specimens are similar to those of raw coal as the confining pressure increases,but there is a significant difference in the yield stage and post-peak stage. As the binder content increases,the axial strain and cohesion of the briquette coal increase,while the elastic modulus and internal friction angle decrease. These results show that the consolidation ability between massive pulverized coal particles can be improved with an increase in binder content,leading to an enhancement in the mechanical strength and rigidity characteristics of the briquette coal to a certain extent. Consequently,the failure mode of briquette coal specimens changes from typical plastic failure to shear failure,presenting ideal elastic-plastic material deformation characteristics. The calculation results of Euclidean distances of eigenvalue vector space reveal that the mechanical characteristics of briquette coal IV are closer to those of raw coal.