Strength Behavior of Fly Ash-Stabilized Soil Reinforced with Coir Fibers in Alkaline Environment

ABSTRACT

Alkaline activation has received much attention in recent years as a method for improving the soil properties. This paper presents the details of laboratory investigation to evaluate the feasibility of using the alkaline activation along with the treated coir fibers for improvements of engineering characteristics of soils and subgrade performance of pavements. In the presence of high alkali solutes, the fly ash (FA) was used as a precursor due to its amorphous nature and high silica-to-alumina ratio. Additionally, this study adopted the physical treatment of the fiber surface with the linseed oil. Treated coir fibers and fly ash were added to soil in 1% and 60% ratios (by weight), respectively. Accordingly, a series of unconfined compressive strength (UCS), modulus of elasticity (Es), direct shear (DS) and California bearing ratio (CBR) tests were conducted on the stabilized soil with and without pairing with treated fibers. By adding alkali-activated (AA) fly ash and inclusion of treated fibers led to increasing deformability and failure strain. Based on the atomic force microscopy tests, the addition of treated fibers contributes to the enhancement of AA-stabilized soil through yielding a denser and more uniform structure. The findings encouraged the application of AA-stabilized soils reinforced with treated fibers to improve the strength of soils in alkaline environment as subgrade of pavements.

摘要

碱活化作为一种改良土壤性质的方法，近年来受到人们的广泛关注。本文介绍了实验室研究的详细情况，以评估将碱活化与处理过的椰纤维一起用于改善土壤工程特性和路面路基性能的可行性. 在高碱溶质存在下，粉煤灰（FA）具有无定形和高硅铝比的特点，被用作前驱体. 此外，本研究采用亚麻油对纤维表面进行物理处理. 处理过的椰纤维和粉煤灰分别以1%和60%的比例（按重量）添加到土壤中。因此，在有或无处理纤维配对的稳定土上进行了一系列无侧限抗压强度（UCS）、弹性模量（Es）、直剪强度（DS）和加州承载比（CBR）试验. 通过添加碱活化（AA）粉煤灰和掺入处理过的纤维，提高了材料的变形能力和破坏应变. 根据原子力显微镜测试，添加处理过的纤维有助于增强AA稳定土的强度，使其结构更加致密和均匀. 研究结果鼓励使用经处理纤维增强的AA稳定土，以提高碱性环境下作为路面路基的土壤强度.

KEYWORDS:

• Soil stabilization
• coir fiber
• treated fibers
• high alkali solutes
• subgrade reinforcement
• alkaline activation

关键词:

• 土壤稳定
• 椰纤维
• 处理过的纤维
• 高碱溶质
• 路基加固
• 碱性活化

Acknowledgments

The authors wish to express their gratitude for the financial assistance provided by the Research Management Centre (RMC) of University Putra Malaysia under Putra Grant (No. 9591800) ‘Behaviour of stabilized soil by alkaline activation and glass fiber’.

Declaration of interest

No potential conflict of interest was reported by the authors

Additional information

Funding

This work was supported by the Universiti Putra Malaysia [9591800].