Abstract:Backfill mining was an effective way of realizing green mining, and the key part of its application was to do some research into the filling materials. The high-water material was a new kind of filling material, the physical and mechanical properties of high-water material that used for goaf filling directly affect the filling stability, solid particles and water are the main components of high-water material, the relative content of which directly affect its physical and mechanical properties. Based on a series of macroscopic and microscopic tests, the basic physical properties and uniaxial compressive strength characteristics of high-water material with different water cement ratio were studied. The results indicated that 1) Microstructure of high-water material stone exhibits a network structure and is very porous, so it can absorb quantities of water which was greater than its weight. The greater the water cement ratio is, the sparser the fissures in reticular formation will be and thus the larger the reticular formation will be. The phenomenon of dehydration became much more evident when the high-water material’s water cement ratio got larger and when it was under the action of uniaxial compression. 2) The stress-strain curve of high-water material is similar to that of rock material, however, the high-water material exhibits high plasticity and can maintain better integrity after reaching peak strength. 3) Under uniaxial compression, the high-water material often show "X" type shear failure when the water cement is relatively high; but it often shows splitting failure when the water cement is relatively low. The uniaxial peak strength and residual strength of high-water material reduced with the increase of its water cement ratio. With the decrease of water cement ratio, the stress-strain curve at the peak strength became much steeper and the strength after the peak stage reduced much faster while its residual strength remained a higher level. 4) The high-water material displays excellent plastic properties and high residual strength, which is suitable for filling material.