New M.E. Thesis Submitted from CIVIL Student


Soil is the cheapest construction material available locally in most of the regions of world. Finding a suitable method to utilize the industrial waste as well as agro waste with soil is a practical way to encourage the sustainable development. Use of industrial waste as a constituent of construction material significantly reduces the construction cost. Nearly 75% of India’s total installed power generation is thermal out of which coal based is 90%. The waste product produced from coal such as fly ash as well as pond ash requires a large area to dispose off. The utilization of the fly ash so produced has drawn attention of experts from various fields for several decades. Since, fly ash has large content of silica and compacted fly ash has high shear strength and low specific gravity results into significant benefit. The bulk utilisation of fly ash is only possible by the way of geotechnical application such as embankment construction, backfill material and sub base material.
The objective of this study is to investigate the geotechnical characteristics of soil - pond ash - rice husk ash & phashogypsum mixture. To achieve this objective compaction tests, CBR tests and durability tests were conducted on test specimen. Pond ash as well as rice husk ash fraction used was 20%, cement was used as an activator as 3% to 5% with phasphogypsum content ranged from 0% to 1% with an increment of 0.5%. CBR tests were conducted at optimum moisture content by varying the cement content as well as phasphogypsum content. The test specimens were cured for 7 days, 14 days and 28 days.
A laboratory testing programme was conducted using silty soil from GNDEC, Ludhiana with pond ash, rice husk ash, cement and Phasphogypsum. The soil on testing was found to be silt of low compressibility.Specimens were prepared at OMC to have maximum density. California bearing ratio value of soil - pond ash - rice husk ash & phashogypsum mixture increased by increasing the cement content and Phasphogypsum. The specimens were prepared by taking mixtures of 20% pond ash, 20% rice husk ash and cement content 3% & 5% with varying phasphogypsum from 0% to 1% with an increment of 0.5% and compacted at OMC which showed substantial growth in strength as compared to those of untreated specimens compacted at same water content. The soil in virgin state was having very low CBR value. The CBR tests were conducted under soaked as well as unsoaked conditions for 7 days, 14 days and 28 days curing period. A substantial increase in CBR was achieved when soil was mixed with pond ash, rice husk ash, cement and phasphogypsum.
Durability characteristics of soil, pond ash, rice husk ash, cement and Phasphogypsum stabilised mix were also studied in this investigation. It showed significant resistance to dry-wet cycles of durability.

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