Strength characteristics of fly ash stabilized with lime and modified with phosphogypsum

The paper presents the strength characteristics of fly ash stabilized with lime and phosphogypsum. A series of unconfined compression strength test and unconsolidated undrained triaxial tests were conducted on the reference mix composed of fly ash, 8% lime and 2% phosphogypsum. The specimens for these tests were prepared and cured for 7, 28, 56 and 90 days with three different curing methods termed as method M1, M2 and M3. The results of this study indicated that the unconfined compressive strength, deviator stress, cohesion, friction angle, initial tangent modulus and secant modulus increased with the increase in curing period. The increase in these parameters was highest for M3 method of curing followed by M1 and M2 respectively. Further to predict these parameters an empirical relationship is proposed which was found to predict the given parameters within acceptable error. It is anticipated that the results of present study will be useful in utilizing the waste materials (fly ash, phosphogypsum) for various geotechnical applications.