Polynomial relationship of compaction properties of silicate-based RHA modified expansive soil for pavement subgrade purposes

IF 0.5 Q4 MATERIALS SCIENCE, COMPOSITES
K. Onyelowe, M. Onyia, E. Onukwugha, Oscar C. Nnadi, I. Onuoha, Fazal E. Jalal
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引用次数: 5

Abstract

The effect of varying proportions of rice husk ash (RHA) on the compaction behaviour of modified soil has been investigated under laboratory conditions. Problematic soils exhibit undesirable characteristics that make them unsuitable for use as foundation materials due to their swell shrink properties. Clay dominant in montmorillonite and illite belongs to such group of soil due to the net negative cations at the surface when exposed to moisture. For this reason, such soils are modified in a stabilization process to improve their mechanical properties. In this research series of preliminary studies were carried out and it was discovered that the studied soil has 73.2% passing number 200 sieve, has liquid limit of 48% and plasticity index of 19%. This helped to classify the soil as A-7-6 soil according to AASHTO classification method. The soil was also classified as poorly graded soil and highly plastic. The dominant mineral is montmorillonite observed by scanning electron microscopy (SEM) method and due to its high affinity with moisture due to cation exchange, the soil swells and shrinks. The soil was treated with 2% to 30% by weight of solid with RHA and the results were observed. The results showed a steady decrease in the maximum dry density (MDD) of the RHA modified soil. The MDD did not reduce beyond the minimum value for clay soil, which is 1.20 g/cm3. The decrease recorded in MDD was due to smaller specific gravity compared to the soil. Conversely, the optimum moisture content increased due to moulding moisture demand of the isomorphic net negative cation exchange. Though the cementing property of the RHA was due to the silicate-based aluminosilicates that provided bonding of the treated material, the blend will need a filler material to achieve a more appropriate densification. Finally, mathematical relationships of a polynomial form were proposed that summarized the total compaction behaviour of the RHA modified soil.
道路路基用硅酸盐基RHA改性膨胀土压实特性的多项式关系
在实验室条件下,研究了不同比例稻壳灰(RHA)对改性土压实性能的影响。有问题的土壤表现出不受欢迎的特性,由于它们的膨胀收缩特性,使它们不适合用作基础材料。以蒙脱土和伊利石为主的粘土,由于其在受潮时表面的净负离子,就属于这类土壤。由于这个原因,这种土壤在稳定过程中进行了改性,以改善其力学性能。本研究进行了一系列的初步研究,发现所研究的土壤200筛合格率为73.2%,液限为48%,塑性指数为19%。这有助于根据AASHTO分类方法将土壤分类为A-7-6土壤。土壤也被归类为差级土壤和高塑性土壤。通过扫描电镜(SEM)观察到,主要矿物是蒙脱土,由于阳离子交换,其与水分的亲和力高,土壤膨胀和收缩。在土壤中添加2% ~ 30%的RHA,观察结果。结果表明,RHA改良土壤的最大干密度(MDD)呈稳定下降趋势。粘土的MDD没有超过最小值1.20 g/cm3。MDD记录的减少是由于与土壤相比比重较小。相反,由于同构净负离子交换的成型水分需求,最佳水分含量增加。虽然RHA的胶结性能是由于硅酸盐基硅铝酸盐提供了处理材料的粘合,但共混物需要填充材料来实现更合适的致密化。最后,提出了一个多项式形式的数学关系,总结了RHA改性土的总压实行为。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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