羟基铝[Al13]^7+对膨胀土自由膨胀率的影响  

Influence on the Hydroxy-aluminum [Al13]^7+ over Free Swell of Expansive Soil

作　　者：刘亮 姚海林 王璐 熊大宁 孔莹 许光 LIU Liang;YAO Hai-lin;WANG Lu;XIONG Da-ning;KONG Ying;XU Guang(Central South Architectural Design Institute Co.,Ltd.,Wuhan 430071,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)

机构地区：[1]中南建筑设计院股份有限公司,武汉430071 [2]中国科学院大学武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071

出　　处：《科学技术与工程》2020年第23期9282-9286,共5页Science Technology and Engineering

基　　金：国家自然科学基金面上项目(41472290,41472286);国家自然科学基金青年科学基金(41402317,41402276)。

摘　　要：利用碱中和滴定法制备羟基铝溶液,通过27Al核磁共振(27Al nuclear magnetic resonance,27Al-NMR)对羟基铝溶液中的[Al13]^7+相对含量进行技术分析,并采取正交实验法确定羟基铝合成过程中影响[Al13]^7+相对含量的主要因素。将羟基铝溶液与膨胀土进行混合交联,研究碱化度和铝土比对胶结样自由膨胀率的影响并探讨胶结土自由膨胀率的变化机理。试验结果表明:在羟基铝的合成中,碱化度是影响[Al13]^7+相对含量的主要因素;[Al13]^7+是改变胶结土自由膨胀率的主要铝形态,它与黏土矿物晶层的亲和力较大,很难被其他阳离子置换出来;胶结土样的自由膨胀率随铝土比的增大而先快速减小然后基本不发生变化,表明了胶结土中黏土矿物对[Al13]^7+的吸附达到了饱和;胶结土自由膨胀率的变化与扩散双电层的厚度有关。The hydroxy-aluminum solution can be prepared by alkali neutralization titration. In the course of synthesizing the hydroxy-aluminum, the main affecting factors of the relative content of [Al13]7+ which was detected and analyzed by 27Al-NMR were determined by the orthogonal experiment design. The cross-linking tests were designed by mixing the hydroxy-aluminum solution and expansive soil, then the influence of the molar ratio of OH- to Al3+ and ratio of total aluminum to expensive soil on free swell was further investigated. Meanwhile, the changing mechanism of free swell of the cemented soil was discussed. From the results of the tests, it is found that the molar ratio of OH- to Al3+ is the critical factor affecting the relative content of [Al13]7+, and that the main aluminum species that change the free swell of the cemented soil is Al13, which is difficult to be substituted because of the stronger affinity with the crystal layer of the clay mineral. With the uniform increase of ratio of total aluminum to expensive soil, the free swell of the cemented soil samples decreases rapidly at first and then stay constantly, indicating that the adsorption from Al13 to the clay mineral of the cemented soil reaches saturation. And the thickness of the diffuse electric double layer is related to the change of the free swell of the cemented soil.

关 键 词：羟基铝 膨胀土 自由膨胀率 碱化度 铝土比 

分 类 号：P574.1[天文地球—矿物学] O641.3[天文地球—地质学]