铝土矿选尾矿制备硅铝聚合材料的反应产物及抗化学侵蚀性能(英文)

以煅烧铝土矿选尾矿为硅铝质原料,以矿渣微粉为促硬剂,以水玻璃为激发剂,制备得到了硅铝聚合材料。运用X射线衍射、扫描电镜、热分析研究了硬化浆体的反应产物及其微观形貌、热性质。通过观察3%硫酸钠溶液、3%硫酸镁溶液、5%硫酸溶液、5%盐酸溶液对砂浆试样外观、质量、强度的影响,研究了其抗化学侵蚀性能,并比较了其与铝酸盐水泥、快硬早强硫铝酸盐水泥、中抗硫酸盐硅酸盐水泥及矿渣硅酸盐水泥的区别。结果表明:反应并不生成晶体物质,而是无定形态的铝硅酸盐;硬化体中呈现片层状显微形貌的物质能够吸附水分,从而在灼烧过程中表现为脱水吸热及质量损失;该片层状物质随着龄期的延长而变得愈发细小和复杂,进而在宏观上表现为强度增长及脱水温度升高;硅铝聚合砂浆分别经3%硫酸钠溶液、3%硫酸镁溶液浸泡28d后,与各水泥砂浆试样比较,其不仅外观完整,而且强度并没有下降,反而具有几乎相同的强度增长,即说明其具有更优异的抗硫酸侵蚀性能;硅铝聚合砂浆与各水泥砂浆经稀酸溶液浸泡28d后,前者不仅能保持原始外观,而且表现为更低的质量及强度损失。

REACTION PRODUCTS AND RESISTANCE TO CHEMICAL ATTACK OF GEOPOLYMERS SYNTHESIZED FROM ORE-DRESSING TAILINGS OF BAUXITE

The geopolymers with excellent mechanical properties were synthesized from calcined ore-dressing tailings of bauxite, ground granulated blast fulrnace slag and sodium silicate. The calcined tailings provide the siliceous and aluminum contents, and ground granulated blast furnace slag and sodium silicate were used as an accelerant and an activator, respectively. The hardened hy-drated paste of geopolymers was characterized by X-ray diffraction, storming electron microscope and thermal analysis to determine the reaction products, morphology and thermal characteristics. The chemical stability (such as sulfate resistance and acid resistance of hardened mortar) was investigated. The mass loss and strength deterioration of geopolymers mortar were compared with those of Portland blast-furnace slag cement and special cement (i.e., including aluminate cement, early strength sulphoaluminate cement, and moderate sulfate resistance Portland cement). It was known that their resistance to chemical attack was better than that of Portland cement. The results show that the main product of geoplymeric reaction is an amorphous hydrated alnuminosilicate. The sheet and lamellar products could adsorb water, and the desorption could make endothermic peak and mass loss when the paste sample exposes to heating environment at 1 000 ℃. The amount of this lamellar product increased and became more complicated with curing ages, resulting in the aggrandizement of strength and increase of temperature in dehydration. The chemical stability tests involved the im-mersion of samples in each solution of sodium sulfate of 3%, magnesium sulfate of 3%, hydrochloric acid of 5% and sulphuric acid of 5%, respectively. The subequal strength growth of geopolymer mortars was shown in different solution of sulfate salt after 28 d im-mersion. However, the flexural strength and compressive strength of special cement mortars were reduced. It was indicated that the geopolymers synthesized from calcined tailings has more excellent sulfate resistance. The performance of geopolymer mortars was superior in a low concentration of acid due to the original appearance and the lowest mass loss and strength deterioration.