Enhancement of subgrade soil properties using coal bottom ash and basalt fiber for sustainable pavement applications

Document Type

Article

Publication Title

Transportation Engineering

Abstract

The stabilization of soil has become a critical focus in geotechnical engineering due to the increasing demand for durable infrastructure and sustainable practices. This study explores the potential of utilizing coal bottom ash (BA), a by-product of coal combustion generated from thermal power plants and artificial basalt fiber (FB) for soil stabilization. This research investigates the effects of varying FB and BA content on the engineering properties of soil, including compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR) as well as split tensile strength (STS). The compaction test was carried out using various proportions of BA (10%, 20%, 30%, and 40%) based on the dry weight of the soil. Using these compaction test results, UCS test were performed for each soil mix to obtain optimum BA content required in soil mix composition. The optimum BA content was obtained as 20% and a small amount i.e., 3% cement was considered to prepare the UCS sample. Varying percentages of FB content (0.5%, 1%, 2%, and 4%) was also added to the soil to improve the tensile strength. From these experiments at optimum BA content of 20%, optimum fiber content observed was 1% to stabilize the soil. This optimum soil mix composition was checked further for CBR and STS values. The results indicated that CBR values rose from 3.36 to 12.52% for the unsoaked state and from 2.45% to 10.10% for the soaked condition post treatment. Similarly, substantial improvement in tensile strength of the soil was also noted. This study highlights the promising potential of BA and FB in sustainable soil improvement, contributing to the development of cost-effective and environmental friendly solutions in geotechnical engineering applications.

DOI

10.1016/j.treng.2025.100377

Publication Date

9-1-2025

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