Abstract This research provides a combination method in quantifying mineral abundances of the black cotton soil (BCS) to reveal its swelling property. The soil was sampled from a roadbed to be built in Niarobi, Kenya, and was found to experience large volumetric expansion (~166%) due to the moisture variation. The wet-chemical analyses and X-ray characterizations (XRD) were undertaken to study the chemical compositions and mineral phases that are presented in the BCS. The quantification of minerals was determined by combining chemical compositions, physical properties (cation-exchange capacity = 75.5 meq 100 g−1, hydroxyl water loss = 10.5%) and the phase identification. A local regression relationship was proposed based on the mass balance of major elements. The BCS was found to consist with clay minerals as nontronite (17.3 wt.%), smectite (10.9% wt.%), chlorite (21.7 wt.%) and interstratified chlorite/smectite (31.9 wt.%). The nonclay minerals of quartz and feldspar were determined to have proportions of 10.2 wt.% and 8.4 wt.%, respectively. This evaluation was also confirmed by the electron microprobe analysis (EMPA) linked with a graphic software and experimentally by the multiple-step precipitation plus additional alkaline/acid and other chemicals treatments. The high content of Na, Ca-based clay minerals found in this work accounts for the large volumetric expansion when the BCS is exposed to water.

中文翻译：

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矿物丰度定量揭示肯尼亚黑棉土的膨胀特性

摘要 本研究提供了一种量化黑棉土（BCS）矿物质丰度以揭示其膨胀特性的组合方法。土壤是从肯尼亚尼亚罗比建造的路基中取样的，发现由于水分变化而经历了大的体积膨胀 (~166%)。进行湿化学分析和 X 射线表征 (XRD) 以研究 BCS 中出现的化学成分和矿物相。通过结合化学成分、物理特性（阳离子交换容量 = 75.5 meq 100 g-1，羟基失水 = 10.5%）和相识别来确定矿物质的量化。基于主要元素的质量平衡提出了局部回归关系。发现 BCS 由粘土矿物组成，如绿脱石 (17.3 wt.%)、蒙脱石 (10. 9% wt.%)、亚氯酸盐 (21.7 wt.%) 和层状亚氯酸盐/蒙脱石 (31.9 wt.%)。石英和长石的非粘土矿物的比例分别确定为 10.2 wt.% 和 8.4 wt.%。该评估还通过与图形软件相关联的电子微探针分析 (EMPA) 以及多步沉淀加上额外的碱/酸和其他化学品处理的实验得到证实。在这项工作中发现的高含量的 Na、Ca 基粘土矿物是 BCS 暴露在水中时体积膨胀大的原因。该评估还通过与图形软件相关联的电子微探针分析 (EMPA) 以及多步沉淀加上额外的碱/酸和其他化学品处理的实验得到证实。在这项工作中发现的高含量的 Na、Ca 基粘土矿物是 BCS 暴露在水中时体积膨胀大的原因。该评估还通过与图形软件相关联的电子微探针分析 (EMPA) 以及通过多步沉淀加上额外的碱/酸和其他化学品处理在实验上得到证实。在这项工作中发现的高含量的 Na、Ca 基粘土矿物是 BCS 暴露在水中时体积膨胀大的原因。