Use of Botswana Fly Ash as Flowable Fill

摘要

In the present work high fly ash content flowable fill of Botswana fly ash has been investigated. The lime and cement in the proportion of 3%, 6%, 9%, 12%, and 15% and water equal to 125% of its liquid limit was mixed with fly ash to produce self leveling fill. The safe bearing capacity (S.B.C) of these fills was determined in the laboratory after 1,2,4, 7, and 15 days using drop test and the Dynamic Cone Penetration (DCP) test were determined in the field after 1, 7, and 28 days. The California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) of the fills were calculated from DCP values using empirical correlations. It was noted that there is no significant effect of lime or cement on seven days strength. The safe bearing capacity attained after seven days were approximately two to four times the safe bearing capacity of most well compacted earthen backfill materials. The CBR of the fills after seven days was found to be more than the requirement for the base and sub base for roads. The findings suggest that the high fly ash flowable fills of Botswana fly ash can successfully be used without any addition of lime or cement.