【作者】 盛广宏；

【导师】 程麟；

【作者基本信息】 南京工业大学 ， 材料学， 2004， 硕士

【摘要】 磷渣在水泥工业中作为原料用于生产水泥时,可以降低煅烧温度提高熟料质量;也可以作为混合材掺入水泥中改善水泥的性能.但是磷渣作为混合材使用时会对硅酸盐水泥产生一些不利的影响,一是早期强度低,二是凝结时间长.这也成为制约磷渣在水泥中应用的重要因素,为了更好地利用磷渣,减少黄磷工业的污染,以及降低水泥工业的环境负荷.本文通过机械活化与化学激发的方法来提高磷渣硅酸盐水泥的早期强度,以及改善凝结时间性能.研究表明,硫酸钠.烧石膏和烧明矾石等都可以有效地提高磷渣硅酸盐水泥 3d 强度2~3MPa,28d 强度 3~5MPa,但硫酸钠的掺加对磷渣硅酸盐水泥的后期强度不利,它们的复合掺加效果却不佳.在使用以硫铝酸钙为主要矿物组成的外加剂以及煅烧地开石时,也有一定的效果,可以提高 3d 和 28d 强度约 2MPa.提高磷渣的比表面积可以提高磷渣硅酸盐水泥的强度,对于比表面积为 341m2/kg 的磷渣,掺量为 30%时,可以达到 P.O.42.5 等级要求,而使用比表面积为 502m2/kg的磷渣,达到同样的等级要求,掺量可以达到 40%.当采用外加剂与机械活化联合使用时,效果更好.联合采用细磨磷渣(即将磷渣细度从 341m2/kg 提高到502m2/kg)与掺加烧石膏(完全替代二水石膏)时,在磷渣掺量为 30%时,可以达到 P.O.52.5 等级要求,磷渣掺量达到 50%时,仍能满足 P.O.42.5 等级要求.当采用磨细磷渣,掺加烧明矾石 3%,在磷渣掺量为 30%时可以达到 P.O.52.5等级要求,掺量达 50%时仍可以满足 P.O.42.5 等级要求. 磷渣对硅酸盐水泥具有显著的缓凝效应,对凝结时间的影响主要受磷渣掺量与细度的影响,掺量越高,缓凝越严重,当磷渣掺量从 30%增加到 50%时,其凝结时间延长约 100min 到 400min;比表面积越大,凝结时间越长.在相同掺量时,掺加比表面积为 502m2/kg 的磷渣比 341m2/kg 的磷渣的硅酸盐水泥的凝结时间延长 60~100min.在使用外加剂改善磷渣水泥的凝结时间时,以硫酸钠和以硫铝酸钙为主要矿物组成的外加剂的效果最佳,而烧石膏与烧明矾石的作用不显著. 通过对磷渣的缓凝机理研究,我们认为磷渣对硅酸盐水泥的缓凝主要是由于水化初期形成的半透水性薄膜对磷渣在碱性条件下形成的羟基磷灰石与氟化 I<WP=4>钙的吸附,导致其密实度增加,水不易透过,从而延缓了水化速度,最终导致了水泥的缓凝.这种吸附是由于磷渣中所含有的磷和氟在水泥水化产物Ca(OH)2 的作用下从磷渣玻璃体中离解出来,磷在碱性溶液中生成羟基磷灰石不断地沉积在水化产物表面,而氟则是形成氟化钙,以氢键或吸附的方式与水化产物结合. 论文对外加剂对磷渣水泥硬化浆体的孔结构.化学结合水与水化产物的影响进行了研究.外加剂的掺加能降低磷渣水泥硬化浆体的总孔隙率,改善孔径分布,使小于 50nm 的凝胶孔增多,而大于 100nm 的有害孔减少,但是硫酸钠却导致 28d 的总孔隙率增加.通过对总孔隙率与抗压强度之间的数学拟合,发现它们之间的关系符合 Rhyshkewitch 公式.通过对硬化浆体的 SEM 图像研究表明,硫酸钠加速了磷渣的解聚,而烧石膏与烧明矾石则可以生成更多的钙矾石.外加剂的加入能提高磷渣水泥的硬化浆体的化学结合水含量,但不同的外加剂的作用是不一样的.对硬化浆体的 Ca(OH)2 含量的影响是硫酸钠和烧石膏能提高其含量,而烧明矾石却导致 Ca(OH)2 含量的下降,这是因为它们在磷渣水泥中的作用机制是不一样的.更多还原

【Abstract】 Phosphorous slag(PS) is used as raw materials which can reduced calcinedtemperature of clinker and improve property of clinker, and it also can be used asmixture of cement to improve its property. When PS is used as mixture of cement,there are two disadvantages , low early-strength and long setting time, which aremain reasons that handicap its utilization in cement industry. For better utilization ofPS, reduction of pollution of phosphorous industry and cutting down theenvironmental load of cement industry, we decide to study on how to improve theproperty of setting time and the early strength of phosphorous slag cement(PSC) bymechanical and chemical activation. By research, we know that sodium sulphate,calcined gypsum and calcined alunite can improve compressive strength of PSCabout 2~3MPa at 3 days and 3~5MPa at 28days, but sodium sulphate will harm thelatter strength of PSC and compound usage of these additves will not be better.Effect of man-made additive and calcined dickite using in PSC is good which canimprove compressive strength about 2MPa at 3days and 28days. Increasing specificsurface of PS can improve strength of PSC. The PSC with 341m2/kg PS at content of30% can reach P.O.42.5 level, but the PSC can reach the same level with 502m2/kgPS at content of 40%. The effect of compound usage of additive and mechanicalactivation will be better than that of only usage one of them. The PSC can reachP.O.52.5 level if calcined gypsum and 30% 502m2/kg PS are used. If the content ofPS reach 50%, the PSC can reach P.O.42.5 level yet. When calcinedgypsum(substituted all dihydrate gypsum) will be used ,the PSC can reach the samelevel of the PSC with calcined gypsum and 502m2/kg PS. Setting of portland cement can be retarded severely by PS, and main fact ofretardation is content of PS and its specific surface. The content is higher, the settingtime of cement is longer. When the content of PS in cement increases from 30% to50%, the setting time of PSC delays from about 100 min to about 400 min. And thespecific surface of PS is higher, the setting time of cement is longer too. The i<WP=6>setting time of cement with 502m2/kg PS is retarded about 60 to 100min than that ofcement with 341m2/kg PS at the same content. Additves can improve the property ofsetting time, and sodium sulphate and additve whose main mineral is C4A3 S arebetter than calcined gypsum and calcined alunite when they are used to improve theproperty of setting time of PSC. By study on the mechanism of retardation of PS, we know that absorption of PSby half-permeation film produced at early time during hydration, which results inhard pervasion by water and other ions, so it retard hydration of cement and settingtime is elongated finally. The process of absorption is that P and F in PS are liberatedby Ca(OH)2 produced during hydration of cement, then P will producehydroxyapatite which deposits on the surface of hydration production by absorptionand F will produce CaF2 which combines with hydration by hydrogen bond. We also study on the influence of additves on pore structure, chemicallycombined water and hydration production of hardened paste of PSC. Additives candecrease total porosity of hardened paste of PSC and improve pore diameterdistribution which is reduction of harmful pore whose pore diameter is above 100nmand increase of gel pore whose pore diameter is low 50nm, but sodium sulphate willinduce increase of total porosity at 28days. The relation between total porosity andcompressive strength agrees to Rhyshkewitch equation by mathematically fitted.Sodium sulphate can accelerate depolymerization of PS while calcined gypsum andcalcined alunite can reduce to produce more AFt by research on SEM photoes ofhardened paste of PSC. Additives can increase content of chemically combinedwater of hardened paste of PSC, but effects of additives are different. Both calcined更多还原