冻融循环作用下煤矸石-铁尾矿烧结多孔砖的损伤性能

Investigation on Damage Performance of Coal Gangue-iron Tailings Sintered Porous Brick under Freeze-thaw Cycles

大宗工业固废建材化利用是工业可持续发展的一项长远战略方针,利用煤矸石、铁尾矿生产烧结砖可为内蒙古地区大宗工业固废综合利用提供新思路。针对内蒙古地区自然环境特征,对煤矸石-铁尾矿烧结多孔砖标准试件进行冻融循环试验,分析冻融前后煤矸石-铁尾矿烧结多孔砖外观、质量、抗压强度、吸水率和体积密度变化情况;基于Wiener过程对试样损伤规律进行分析,以相对质量损伤为指标建立可靠度模型,并对指标选取合理性进行验证,计算漂移系数和扩散系数求解冻融循环作用后煤矸石-铁尾矿烧结多孔砖可靠度函数曲线;利用冻融寿命预测模型对室内外冻融循环次数进行转化,并对冻融循环作用后煤矸石-铁尾矿烧结多孔在不同阈值条件进行寿命预测。结果表明:煤矸石-铁尾矿烧结多孔砖标准试件抗压强度为10.6 MPa,吸水率为13.3%,体积密度为1779.7 kg/m^(3);煤矸石-铁尾矿烧结多孔砖性能随冻融循环次数增加劣化程度加深,其质量、抗压强度、吸水率和体积密度损伤度分别为7.1%、38%、18%和3.6%,同时冻融循环后砖体表面出现隆起、微裂缝和轻微剥落现象;对可靠度函数曲线分析可知煤矸石-铁尾矿烧结多孔砖损伤符合材料破坏特点,在阈值为0.2、0.3、0.4条件下,煤矸石-铁尾矿烧结多孔砖耐久性寿命分别为11.1、35.4、85.6年。

The utilization of bulk industrial solid waste building materials is a long-term strategic policy for the sustainable development of industry.The use of coal gangue and iron tailings to produce sintered bricks can provide new ideas for the comprehensive utilization of bulk industrial solid waste in Inner Mongolia.According to the characteristics of natural environment in Inner Mongolia,the freeze-thaw cycle test was carried out on the standard specimens of coal gangue-iron tailings sintered porous brick.The changes of appearance,quality,compressive strength,water absorption and bulk density of coal gangue-iron tailings sintered porous brick before and after freeze-thaw were analyzed.Based on the Wiener process,the damage law of the sample was analyzed,and the reliability model was established with the relative mass damage as the index,and the rationality of the index selection was verified.The drift coefficient and diffusion coefficient were calculated to solve the reliability function curve of coal gangue-iron tailings sintered porous brick after freeze-thaw cycle.The freeze-thaw life prediction model was used to transform the number of indoor and outdoor freeze-thaw cycles,and the life prediction of coal gangue-iron tailings sintered porous under different threshold conditions after freeze-thaw cycles was carried out.The results show that the compressive strength of the standard specimen of coal gangue-iron tailings sintered porous brick is 10.6 MPa,the water absorption rate is 13.3%,and the volume density is 1779.7 kg/m^(3);the performance of coal gangue-iron tailings sintered porous bricks deteriorates with the increase of freeze-thaw cycles,and its mass,compressive strength,water absorption and bulk density damage are 7.1%,38%,18%and 3.6%,respectively.At the same time,the surface of the brick appears uplift,micro cracks and slight spalling after freeze-thaw cycles,analysis of reliability function curve shows that the damage of coal gangue-iron tailings sintered porous brick conforms to the characteristics of material damage.Under the threshold of 0.2,0.3 and 0.4,the durability life of coal gangue-iron tailings sintered porous brick is 11.1 years,35.4 years and 85.6 years respectively.