赤泥对道路硅酸盐水泥性能和矿物组成的影响

Effect of Red Mud on Properties and Mineral Composition of Portland Cement for Road

以赤泥、砂岩和石灰石为原料进行赤泥道路硅酸盐水泥的制备研究.分析了赤泥的掺加对道路硅酸盐水泥矿物组成和基本性能的影响.结果表明:以赤泥为部分原料可以成功制备以C_3S,C_2S和C_4AF为主要矿物相的道路硅酸盐水泥熟料;赤泥道路硅酸盐水泥熟料掺加5%(质量分数)的二水石膏可以制备出各项性能优异的赤泥道路硅酸盐水泥;与普通道路硅酸盐水泥相比,赤泥道路硅酸盐水泥的早期抗压强度偏低;虽然预先对赤泥进行了脱碱处理(脱碱后赤泥中总碱含量(质量分数)<1%),但当其掺量(质量分数)超过26%时,赤泥道路硅酸盐水泥熟料中的碱仍会对水泥矿物的形成产生不利影响;赤泥道路硅酸盐水泥熟料中的碱大部分以硫酸钾(钠)的形式存在于水泥熟料的中间相中;随着赤泥道路硅酸盐水泥水化龄期的延长,放射性核素^(226)Ra的放射性比活度不断升高,^(232)Th变化不大,^(40)K则不断降低;赤泥道路硅酸盐水泥的外照指数为0.87,对环境的放射性影响处在安全范围内.

Red mud,limestone and sandstone were used to prepare Portland cement for road.The effect of red mud addition on the structure and properties of Portland cement for road was studied.The results show that the major mineral phases of red mud Portland cement for road clinker are C3S,C2S and C4AF.Red mud based Portland cement for road with excellent properties can be prepared by grinding the clinker with 5% dehydrate gypsum.Compared with ordinary Portland cement for road,red mud Portland cement for road has a lower early compressive strength.Although red mud was dealkalized in advance（total alkali content in dealkalized red mud（by mass）1%）,the alkali of the Portland cement for road clinker can still make adverse effect on minerals formation of Portland cement for road if the addition of dealkalized red mud（by mass）exceeds,26%.The alkali in the sintering system exist mainly in the intermediate phase of clinker of red mud Portland cement for road in the form of K2SO4 or Na2SO4.The radioactivity specific activity of ^226Ra increases along with hydration length of time increasing,^40K is just opposite,-（232）Th is basically unchanged.The external exposure index of red mud based Portland cement for road is 0.87,the external exposure indexes of it in different curing ages are all less than the limit.