腐蚀环境中铝土矿超细尾砂-水泥充填材料的损伤特征研究

Damage characteristics of bauxite superfine tailing sand-cement filling material in corrosive environment

为了对铝土矿资源进行资源化利用和保障矿山安全作业,利用铝土矿超细尾砂制备水泥基充填料。开展单轴压缩试验和计算机断层扫描(CT)试验,研究了样品在腐蚀环境中的性能和结构劣化规律,并通过显微图像揭示了腐蚀作用的微观机理。结果表明:在0至360天的腐蚀时间内,超细尾砂-水泥充填材料的抗压强度和变形模量逐渐下降,变化速率先慢后快;细观裂隙在腐蚀过程中逐渐扩张,面孔隙率呈指数型增长趋势;提高充填料浆的浓度有利于材料强度的提高,但提升效果在腐蚀溶液的长期影响下逐渐减弱;抗压强度与面孔隙率负线性相关关系,说明宏观力学性能与细观结构的损伤具有一定同步性;腐蚀性离子的侵入和化学作用使得水化产物微观形态发生演变,导致材料强度的衰减。

In order to make resourceful use of bauxite resources and ensure safe mine operations,bauxite superfine tailings were used to prepare cement-based filling material.Uniaxial compression tests and computed tomography(CT)tests were carried out to investigate the performance and structural deterioration of the samples in the corrosive environment,and microscopic images were used to reveal the microscopic mechanism of the corrosive effect.The results showed that the compressive strength and deformation modulus of the superfine tailing sand-cement filling material gradually decreased during the corrosion time from 0 to 360 days,with the change rate being slow at first and then fast;The fine fracture gradually expanded during the corrosion process,and the surface porosity showed an exponential growth trend;Increasing the concentration of the filling slurry was beneficial to the improvement of the material strength,but the enhancement effect gradually weakened under the long-term influence of the corrosive solution;The negative linear correlation between compressive strength and surface porosity indicates that the macro-mechanical properties are somewhat synchronous with the damage to the fine structure;The intrusion of corrosive ions and chemical effects cause the micro-morphology of the hydration products to evolve,resulting in the decay of the material strength.