GEOTECHNICAL ASSESSMENT OF HIGHLY SALINE SOIL STABILIZED WITH FLY ASH

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The study evaluated Class C fly ash–cement blends for stabilizing highly saline soil collected near Nirma Road in Bhavnagar, Gujarat. The untreated soil contained about 12% salt, had an electrical conductivity (EC) of 21,500 μS/cm, and showed low strength and bearing capacity. Researchers tested mixes containing 10%, 20%, or 30% fly ash with 6% or 9% cement, assessing EC, unconfined compressive strength (UCS), durability, and soaked California Bearing Ratio (CBR).<br /><br />Treatment substantially improved the soil’s geotechnical performance and reduced salinity. EC fell to 7,270–8,730 μS/cm across the tested blends. Soaked CBR rose from 1.62 for untreated soil to as high as 117.26 in the reported results, while effective CBR values for treated mixes exceeded the 5% threshold cited for roads carrying more than 450 vehicles per day. The 6% cement mixes failed the first durability wetting cycle. Among the 9% cement mixes, the 30% fly ash blend had the lowest average weight loss (9.20%) and the highest reported residual strength.<br /><br />The authors identify 30% fly ash with 9% cement as the most effective mix, reporting that it provided the strongest and stiffest stabilization and met relevant IRC criteria for pavement subgrade and sub-base applications, as well as embankments. Overall, the findings indicate that locally available fly ash and cement can improve the strength, bearing capacity, durability, and salinity characteristics of highly saline soil.

Keywords

Class C fly ash

cement stabilization

saline soil

Bhavnagar Gujarat

electrical conductivity

unconfined compressive strength

California Bearing Ratio

soil stabilization

durability

pavement subgrade